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Article title: 1
Reconfigured cyanogenic glucoside biosynthesis in Eucalyptus cladocalyx involves a cytochrome P450 2
CYP706C55 3
4
5
Short title (not exceeding 50 characters and spaces): 6
Aunique CYP706 in prunasin synthesis in Eucalyptus 7
All author names and affiliations: 8
Cecilie Cetti Hansen1, 2, Mette Sørensen1, 2, Thiago A. M. Veiga3, Juliane F. S. Zibrandtsen1,6 , Allison M. 9
Heskes1, Carl Erik Olsen1,2, Berin A. Boughton4, Birger Lindberg Møller1,2,5, Elizabeth H. J. Neilson1,2 10
Affiliations: 11 1 Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of 12
Copenhagen, Thorvaldsensvej 40, Frederiksberg C, Copenhagen, Denmark 13 2 VILLUM Center for Plant Plasticity, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg C, 14
Copenhagen, Denmark 15 3 Department of Chemistry, Federal University of São Paulo, Diadema, Brazil 16 4 Metabolomics Australia, School of BioSciences, The University of Melbourne, Vic. 3010, Australia 17 5 Center for Synthetic Biology, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg C, 18
Copenhagen, Denmark 19
Present addresses 20 6 Syngenta, Crescent House, Tower Business Park, M20 2JE Manchester, United Kingdom 21
Corresponding author: 22
Elizabeth H. J. Neilson 23
ORCID: 0000-0002-8279-9906 25
Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of 26
Copenhagen, Denmark 27
One sentence summary: 28
Cyanogenic glucoside biosynthesis in Eucalyptus cladocalyx requires an additional pathway step, involving 29
three CYPs from the CYP79, CYP706 and CYP71 families, and a glucosyltransferase UGT85. 30
31
List of author contributions: 32
EHJN conceived the study and research plans; CCH, MS, TAM, JFSZ and EHJN performed the experiments; EHJN, 33
BLM, AMH and BB supervised experimental work; CEO and BB provided technical assistance; CCH, MS and EHJN 34
analyzed the data; CCH wrote the draft with contributions from MS, EHJN, and BLM. All authors have reviewed 35
and approved the final manuscript. 36
Funding information: 37
Plant Physiology Preview. Published on October 8, 2018, as DOI:10.1104/pp.18.00998
Copyright 2018 by the American Society of Plant Biologists
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2
This research was supported by the “VILLUM Research Center for Plant Plasticity” (Project No. 7523), by the 38
UCPH Excellence Program for Interdisciplinary Research to Center for Synthetic Biology, and by an ERC 39
Advanced Grant (ERC-2012-ADG_20120314, Project No. 323034) to BLM. EHJN was supported by a Young 40
Investigator Program fellowship from the VILLUM Foundation (Project No. 13167), a grant from the 41
Carlsberg Foundation (Grant no. 2013_01_0908), and by a Danish Independent Research Council Sapere 42
Aude Research Talent Post Doctoral Stipend (Grant No. 6111-00379B). TAMV was supported by a visiting 43
professor fellowship from the Fundação de Amparo a Pesquisa do Estado de São Paulo (#FAPESP BPE 44
2014/11811-2). AMH was supported by a Marie Skłodowska Curie Individual Fellowship (Project No. 45
658677). Mass spectrometry imaging was conducted at Metabolomics Australia located at the School of 46
BioSciences, The University of Melbourne, Australia, which is an NCRIS initiative under Bioplatforms 47
Australia Pty Ltd. 48
Abstract 49
Cyanogenic glucosides are a class of specialized metabolites widespread in the plant kingdom. Cyanogenic 50
glucosides are α-hydroxynitriles, and their hydrolysis releases toxic hydrogen cyanide providing an effective 51
chemical defense against herbivores. Eucalyptus cladocalyx F. Muell. is a cyanogenic tree, allocating up to 52
20% of leaf nitrogen to the biosynthesis of the cyanogenic monoglucoside, prunasin. Here, mass 53
spectrometry analyses of E. cladocalyx tissues revealed spatial and ontogenetic variation in prunasin 54
content, as well as the presence of the cyanogenic diglucoside amygdalin in flower buds and flowers. 55
Identification and biochemical characterization of the prunasin biosynthetic enzymes revealed a unique 56
enzyme configuration for prunasin production in E. cladocalyx. Our result indicates that a multifunctional 57
cytochrome P450 (CYP), CYP79A125, catalyzes the initial conversion of L-phenylalanine into its 58
corresponding aldoxime, phenylacetaldoxime; a function consistent with other members of the CYP79 59
family. In contrast to the single multifunctional CYP known from other plant species, the conversion of 60
phenylacetaldoxime to the α-hydroxynitrile, mandelonitrile, is catalyzed by two distinct CYPs. CYP706C55 61
catalyzes the dehydration of phenylacetaldoxime, an unusual CYP reaction. The resulting phenylacetonitrile 62
is subsequently hydroxylated by CYP71B103 to form mandelonitrile. The final glucosylation step to yield 63
prunasin is catalyzed by an UDP-glucosyltransferase, UGT85A59. Members of the CYP706 family have not 64
previously been reported to participate in the biosynthesis of cyanogenic glucosides and the pathway 65
structure in E. cladocalyx represents an example of convergent evolution in the biosynthesis of cyanogenic 66
glucosides in plants. 67
68
Introduction 69
Cyanogenic glucosides are a class of specialized metabolites found widespread in the plant kingdom. They 70
are present in diverse taxa including species in the genera Pteridium (monilophyte), Taxus (gymnosperm), 71
Sorghum (monocot), Manihot, Trifolium, Prunus and Eucalyptus (eudicots) (Vetter 2017). Upon tissue 72
disruption, such as would be caused by herbivory, the cyanogenic glucoside is hydrolyzed by a specific β-73
glucosidase that cleaves off the sugar moiety. The resulting cyanohydrin dissociates, spontaneously or 74
catalyzed by an α-hydroxynitrile lyase, resulting in the release of toxic hydrogen cyanide. This process is 75
known as cyanogenesis (Gleadow and Møller 2014). Their ability to release hydrogen cyanide makes 76
cyanogenic glucosides chemical defense molecules against generalist herbivores and pathogens (Gleadow 77
and Woodrow 2002). Cyanogenic glucosides have also been shown to constitute a source of reduced 78
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3
nitrogen that are mobilized by endogenous turnover pathways (Bjarnholt et al. 2018; Pičmanová et al. 79
2015; Schmidt et al. 2018a). 80
The biosynthetic pathway genes for a cyanogenic glucoside were first identified and cloned from sorghum 81
(Sorghum bicolor), which accumulates the tyrosine-derived dhurrin (Bak et al. 1998; Jones et al. 1999; Koch 82
et al. 1995). This provided a starting point for the identification of cyanogenic glucoside pathway genes in 83
other plant species. The biosynthetic pathway for the valine-derived linamarin and isoleucine-derived 84
lotaustralin has been elucidated from cassava (Manihot esculenta) (Andersen et al. 2000; Jørgensen et al. 85
2011; Kannangara et al. 2011) and Lotus japonicus (Forslund et al. 2004; Takos et al. 2011), and recently the 86
full pathway for the phenylalanine-derived diglucoside amygdalin from almond (Prunus dulcis) was 87
identified (Thodberg et al. 2018). In species with characterized cyanogenic glucoside biosynthetic pathways, 88
the production of monoglucosides involves two cytochrome P450s (CYPs) and a soluble UDP-89
glucosyltransferase (UGT). The first CYP is a member of the CYP79 family and catalyzes the conversion of an 90
amino acid to the corresponding aldoxime. A CYP71 or CYP736 family member subsequently converts the 91
aldoxime to a cyanohydrin. The labile cyanohydrin is stabilized by glucosylation to form the final cyanogenic 92
glucosides in a reaction catalyzed by a UGT from the UGT85 family. Work on dhurrin biosynthesis in S. 93
bicolor shows that the two CYPs and UGT of the pathway form a metabolon enabling efficient channeling 94
between enzymes that avoids the accumulation of toxic intermediates (Bassard et al. 2017; Laursen et al. 95
2016). 96
Eucalyptus is a large genus with over 800 species (Coppen 2002). They are the world’s most widely planted 97
forest hardwood trees due to their fast growth, environmental plasticity and exceptional wood properties 98
(Myburg et al. 2014). The trees are grown for industrial purposes such as the production of pulp for paper, 99
firewood, charcoal, and essential oils. Eucalyptus plants synthesize a broad spectrum of specialized 100
metabolites including terpenes, phenolics, formylated phloroglucinols, and cyanogenic glucosides (Eschler 101
et al. 2000; Gleadow et al. 2008; Marsh et al. 2017; Padovan et al. 2014). Very little is known about the 102
biosynthesis of specialized metabolites in Eucalyptus. The genome of E. grandis published in 2014 (Myburg 103
et al. 2014) will potentially facilitate the identification of enzymes involved in these pathways. E. grandis 104
has many tandem duplicated genes and tandem expanded clusters as exemplified by the large number of 105
terpene synthase genes (113) and the expansion of some phenylpropanoid genes (Kulheim et al. 2015; 106
Myburg et al. 2014). The significant expansion of some gene families in Eucalyptus provides challenging 107
obstacles towards the identification of pathway genes due to the large number of possible candidates. 108
More than 400 Eucalyptus species have been screened for cyanogenesis and 23 cyanogenic species have 109
been identified, all containing prunasin as the major cyanogen (Fig. 1, B) (Gleadow et al. 2008). The South 110
Australian species E. cladocalyx (sugar gum) was first reported to be cyanogenic in 1928 (Finnemore and 111
Cox 1928) and a few years later the foliar hydrogen cyanide source was identified as prunasin (Finnemore 112
et al. 1935). In particular, the apical tips and young leaf tissue of E. cladocalyx can be highly cyanogenic with 113
up to 20% of leaf nitrogen allocated to prunasin biosynthesis (Gleadow et al. 1998; Gleadow and Woodrow 114
2000b). Cyanogenic Eucalyptus species display unique ontogenetic variation. For example, E. cladocalyx has 115
high levels of prunasin as a seedling compared to adult, while the opposite trend is observed for 116
E. yarraensis and E. camphora (Goodger et al. 2006; Neilson et al. 2011). As such, cyanogenic Eucalyptus 117
species are an excellent system to investigate the regulation of chemical defense (Møller 2010). 118
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In this study, we investigate the spatial and ontogenetic variation and localization of cyanogenic glucoside 119
accumulation in E. cladocalyx. Furthermore, we report the identification and functional characterization of 120
the enzymes catalyzing the formation of prunasin from L-phenylalanine in E. cladocalyx. We show that the 121
conversion of phenylalanine into the corresponding cyanohydrin requires the sequential action of three 122
CYPs, and includes the production of a free nitrile intermediate. One of the CYPs belongs to the CYP706 123
family, a family not previously reported to be involved in the synthesis of cyanogenic glucosides. 124
Results 125
Spatial distribution of cyanogenic glucosides 126
Prunasin extracts of expanded juvenile leaves from young E. cladocalyx plants (4 months), along with 127
expanded adult leaves, immature flower buds, mature flower buds, flowers and mature fruit from mature 128
trees were analyzed by liquid chromatography-mass spectrometry (LC-MS) (Fig. 1). Prunasin was detected 129
in all tissues examined. The lowest levels of prunasin were detected in young and adult leaves (17 ± 2.8 130
μg/mgDW and 14 ± 4.2 μg/mgDW, respectively) and the highest levels were found in immature and mature 131
flower buds (62 ± 12 μg/mgDW and 53 ± 9 μg/mgDW, respectively) with intermediate levels detected in fruit 132
(43 ± 1 μg/mgDW), and flowers (40 ± 1 μg/mgDW). Additionally, the diglucoside amygdalin (Fig. 1, B) was 133
found in the mature flower buds (4 ± 1.8 μg/mgDW) and flowers (9 ± 0.6 μg/mgDW) accounting for 134
approximately 6% and 18% of total cyanogenic content, respectively (Fig. 1, A). 135
The use of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) to map the 136
spatial localization of prunasin and amygdalin within prepared tissues, revealed prunasin to be localized to 137
the mesophyll and vascular tissue of seedling and adult E. cladocalyx leaves (Fig. 2, A-B). Amygdalin was not 138
detected in the leaf material using this method. MALDI-MSI of an E. cladocalyx flower bud demonstrated 139
the presence of prunasin in the ground tissue of the ovary, hypanthium and operculum, as well as in 140
filaments and anthers. Amygdalin was observed to be co-localized with prunasin, specifically in the 141
filaments and staminal ring region (Fig. 2, C-D). 142
Phenylalanine is the precursor for prunasin synthesis in E. cladocalyx 143
Cyanogenic glucosides are known to be derived from amino acids (Gleadow and Møller 2014), and thus we 144
expected prunasin in E. cladocalyx to be derived from L-phenylalanine, based on its structure (Fig. 1, B). To 145
verify this, L-[14C]-phenylalanine was administered to apical tips, expanding leaves and fully expanded 146
leaves. All tested tissues demonstrated activity of the prunasin biosynthetic enzymes by the ability to 147
synthesize prunasin from L-phenylalanine (Fig. 3). 148
Identification and testing of three candidate genes involved in prunasin biosynthesis 149
A candidate CYP79 was identified by PCR, using cDNA generated from young leaves of E. cladocalyx and 150
primers designed to the E. yarraensis CYP79A34 (Neilson 2012). Based on characterized cyanogenic 151
glucoside biosynthetic pathways, candidate genes belonging to CYP71 and UGT85 families that showed high 152
expression in an E. cladocalyx transcriptome and no or very low expression in the acyanogenic E. globulus 153
transcriptome were identified (Spokevicius et al. 2017). Degenerate primers were designed to anneal to the 154
UTR regions of the CYP71 and UGT85 orthologs from the E. grandis genome available on Phytozome 155
(Goodstein et al. 2012) and used to isolate the two gene sequences from E. cladocalyx cDNA. The CYPs 156
where named CYP79A125 and CYP71B103 by David Nelson for the Standardized Cytochrome P450 157
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5
Nomenclature Committee (Nelson 2009), and the UGT candidate was named UGT85A59 according to the 158
standard UGT Nomenclature Guidelines (Burchell et al. 1991; Mackenzie et al. 2005). 159
Testing of the three candidates by co-infiltration into Nicotiana benthamiana leaves only resulted in 160
formation of trace amounts of prunasin (Fig. 4, A; Supplemental Fig. S1). The data, however, confirmed that 161
CYP79A125 and UGT85A59 were functionally active in N. benthamiana. Expression of CYP79A125 resulted 162
in the production of glucosylated phenylacetaldoxime (Supplemental Fig. S2). This suggests that CYP79A125 163
can catalyze the conversion of L-phenylalanine into phenylacetaldoxime that subsequently becomes 164
glucosylated by endogenous N. benthamiana UGTs. Co-expression of UGT85A59 showed an increase in 165
glucosylated phenylacetaldoxime, demonstrating that UGT85A59 is active and able to glucosylate 166
phenylacetaldoxime. 167
CYP706C55 is involved in prunasin biosynthesis 168
To identify other potential candidates involved in prunasin biosynthesis, a transcriptome was prepared 169
from the highly cyanogenic and biosynthetically active apical tips of E. cladocalyx. CYP71B103 and 170
CYP79A125 were the second and third most highly expressed CYPs, respectively, and UGT85A59 was the 171
highest expressed UGT. The most highly expressed CYP in the transcriptome belonged to the CYP706 172
family. This CYP706 was named CYP706C55 (Nelson 2009) and selected for functional analysis. 173
CYP706C55 was tested by transient expression in N. benthamiana together with the previously identified 174
pathway candidates. Expression of CYP79A125, CYP706C55 and UGT85A59 resulted in small amounts of 175
prunasin (Fig. 4, A). However, combined expression of all three CYP candidate genes with UGT85A59 176
resulted in high accumulation of prunasin (Fig. 4, A). Additionally, a novel peak with m/z 404 was observed 177
and tentatively identified as a malonic acid ester of prunasin (Supplemental Fig. S3). Malonic acid 178
derivatives have previously been observed upon transient expression in Nicotiana sp. (Franzmayr et al. 179
2012; Tian and Dixon 2006; Ting et al. 2013), likely as a detoxification mechanism. No prunasin or 180
derivatives thereof were observed in the negative control where no E. cladocalyx genes were expressed. 181
Likewise, no prunasin was observed upon expression of CYP71B103, CYP706C55 and UGT85A59, confirming 182
that CYP79A125 is required for prunasin production in N. benthamiana. Small amounts of prunasin were 183
observed if the three CYPs were co-expressed, indicating that endogenous N. benthamiana 184
glycosyltransferases can glycosylate the mandelonitrile to some extent. However, the prunasin levels 185
increased 50-fold upon co-expression of UGT85A59 (Fig. 4, A). 186
To establish the order of the catalytic activity of CYP71B103 and CYP706C55 in prunasin biosynthesis, 187
microsomes were prepared from infiltrated N. benthamiana leaves and assayed using radioactively labelled 188
L-phenylalanine as substrate. Microsomes with CYP79A125 activity converted L-phenylalanine into a 189
product that co-migrated with phenylacetaldoxime (Fig. 4, B). Microsomes with CYP79A125 and CYP706C55 190
produced phenylacetaldoxime and phenylacetonitrile, and microsomes with all three CYPs showed 191
production of phenylacetaldoxime and mandelonitrile. Microsomes with CYP79A125 and CYP71B103 only 192
produced phenylacetaldoxime, and the negative control without E. cladocalyx CYPs did not show any 193
product formation. In summary, based on transient expression analysis and microsomal assays, we 194
demonstrate a route for prunasin biosynthesis in E. cladocalyx leaves. Specifically, CYP79A125 converts L-195
phenylalanine into phenylacetaldoxime, which is then dehydrated into phenylacetonitrile by CYP706C55, 196
hydroxylated by CYP71B103 to form mandelonitrile, and finally glucosylated by UGT85A59 to form prunasin 197
(Fig. 4, C). 198
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Phylogenetic analysis of the CYP79, CYP706, CYP736 and CYP71 families 199
The amino acid sequences of CYP79A125, CYP706C55 and CYP71B103 were subjected to phylogenetic 200
analysis together with functionally characterized CYP members from the CYP79, CYP706, CYP71 and CYP736 201
families (Fig. 5). These CYP families all contain at least one member involved in cyanogenic glucoside 202
biosynthesis (Supplemental Table S1). All functionally characterized CYP79 members convert amino acids 203
into their corresponding oximes (Sørensen et al. 2018), including 12 CYP79 members involved in cyanogenic 204
glucoside biosynthesis. In contrast, members of the CYP71 family show broad functional diversity 205
(Supplemental Table S1). The cyanogenic glucoside CYP71 members are distributed across several 206
subfamilies, and this study introduces the first CYP71B involved in cyanogenic glucoside biosynthesis. Fewer 207
CYPs belonging to the CYP706 and CYP736 families have been functionally characterized, with only a single 208
member in each of the CYP706 and CYP736 families known to participate in cyanogenic glucoside 209
biosynthesis. 210
211
Prunasin accumulation through leaf ontogeny 212
The spatial variation of leaf prunasin was measured during plant development and prunasin was extracted 213
from apical tips, expanding leaves and fully expanded leaves in plants at 4 months, 7 months and 10 214
months of age. Quantitative variation in prunasin accumulation was observed throughout leaf ontogeny 215
(Fig. 6, A). The most cyanogenic tissue was the apical tips in 4-month-old plants. Accumulation of prunasin 216
decreased with leaf age; in 4-month-old plants prunasin accumulated to 45 ± 5 μg/mgDW in apical tips and 217
decreased to 25 ± 2 μg/mgDW in expanding leaves and 17 ± 3 μg/mgDW in fully expanded leaves. In older 218
plants at 7- and 10-months of age, prunasin accumulation in leaves was lower and showed less variation 219
between leaf types and plant age not exceeding 11 μg/mgDW. 220
Expression of CYP79A125 and CYP706C55 is positively correlated 221
Expression of the characterized biosynthetic pathway genes were analyzed in apical tips, expanding and 222
fully expanded leaves in plants at 4-, 7- and 10-months of age (Fig. 6, B). Expression of all genes was 223
observed in all tested tissues, consistent with their ability to synthesize prunasin (Fig. 3; Fig. 6, A). Biological 224
replicates showed a relatively large variation in expression, however, most individuals showed the same 225
trend across tissues and time. In particular, all plants except one showed the lowest CYP79A125 expression 226
in expanded leaves at the three different time points. A Pearson correlation analysis revealed that 227
expression of the CYPs correlated; expression of CYP79A125 correlated with CYP706C55 (P < 0.01) and 228
CYP71B103 (P < 0.01), and expression of CYP706C55 and CYP71B103 also correlated (P < 0.05) (Fig. 6, C). 229
UGT85A59 was generally highly expressed and did not correlate with the expression of the CYPs. 230
Discussion 231
Prunasin accumulation varies between tissue type and plant age 232
The accumulation of cyanogenic glucosides was investigated in different tissues of E. cladocalyx by LC-MS 233
and MALDI-MSI. At the overall spatial level, the highest prunasin concentration (62 ± 12 μg/mgDW) was 234
found in reproductive tissues (Fig. 1). In addition, E. cladocalyx leaf tissue was most cyanogenic in 4-month- 235
old plants and then decreased with plant age, and in particular prunasin accumulation was found to 236
decrease by leaf age with apical tips being the most cyanogenic followed by expanding leaves and 237
expanded leaves, respectively (Fig. 6). This is in agreement with a previous study observing relatively high 238
cyanide potentials in flower buds, flowers and fruits (Gleadow and Woodrow 2000b) and reports showing 239
that juvenile E. cladocalyx leaves are more cyanogenic than adult leaves, with the inverse relationship 240
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between leaf age and cyanogenic glucoside concentration (Gleadow and Woodrow 2000b; Goodger et al. 241
2006). Only in young 1-week-old seedlings, prunasin content was found to be insignificant (Gleadow and 242
Woodrow 2000b). We also identified the presence of the cyanogenic diglucoside amygdalin E. cladocalyx 243
(Fig. 1), with the highest levels in the flower buds and flowers (4 ± 2 μg/mgDW and 9 ± 1 μg/mgDW, 244
respectively). Amygdalin has not previously been reported to be present in E. cladocalyx. Cyanogenic 245
diglucosides, including amygdalin, were previously identified in E. camphora, with the highest 246
concentration also identified in reproductive tissue (Neilson et al. 2011). 247
Juvenile E. cladocalyx plants tend to be more cyanogenic compared to adult plants (Goodger et al. 2006). 248
However, this is not the case in all cyanogenic Eucalyptus species and the ontogenetic trajectory of 249
cyanogenic glucoside production is known to differ between some species. In E. camphora, foliar 250
cyanogenic glucoside production was found to increase with plant age as prunasin accumulation increased 251
from seedling to sapling to adult (Neilson et al. 2011). A similar pattern has been observed for 252
E. polyanthemos (Goodger et al. 2004). A different trajectory was observed for E. yarraensis, where a 253
detailed study of prunasin concentration through ontogeny revealed that production gradually increased 254
with a maximum concentration at around 240 days after sowing; thereafter, prunasin accumulation 255
declined with age (Goodger et al. 2007). The species-specific differences in the onset of cyanogenic 256
glucoside production provide a unique experimental system for studying the role and regulation of 257
cyanogenic glucoside production. 258
The high concentration of cyanogenic glucosides in young plants, apical tips and reproductive tissue of 259
E. cladocalyx is in accordance with the optimal defense theory of plant defense, whereby the most 260
vulnerable and important structures are the most highly defended (Rhoades 1979). These results support 261
the general role of cyanogenic glucosides as chemical defense compounds against generalist herbivores 262
and pathogens (Gleadow and Woodrow 2002). In recent years, it has become apparent that cyanogenic 263
glucosides perform additional roles in plant metabolism, for example, as storage molecules or in quenching 264
reactive oxygen species (ROS) (Gleadow and Møller 2014; Schmidt et al. 2018a). Enzymes and 265
intermediates in endogenous recycling of auto-toxic cyanogenic glucosides, including prunasin and 266
amygdalin, have been identified (Bjarnholt et al. 2018; Jenrich et al. 2007; Pičmanová et al. 2015). Tissue 267
based localization studies using MALDI-MSI, provide important information to aid the understanding of 268
specialized metabolite multi-functionality in planta (Bjarnholt et al. 2014; Boughton et al. 2016). Using 269
MALDI-MSI, we show that prunasin is localized to the mesophyll and vascular tissue of seedling and adult E. 270
cladocalyx leaves (Fig. 2, A-B). The localization of prunasin in the vascular tissue of E. cladocalyx leaves 271
suggests the transport of cyanogenic glucosides within the plant. Transport of cyanogenic glucosides is 272
known in other cyanogenic species including M. esculenta (Jørgensen et al. 2005), Hevea brasiliensis 273
(Selmar 1993; Selmar et al. 1988) and S. bicolor (Darbani et al. 2016; Selmar et al. 1996). Once transported, 274
it is hypothesized that the cyanogenic glucoside is recycled and provides a source of reduced carbon and 275
nitrogen (Bjarnholt et al. 2018; Pičmanová et al. 2015). 276
MALDI-MSI of the E. cladocalyx flower bud revealed distinct patterns of prunasin and amygdalin 277
localization. Prunasin was widely distributed throughout the ground tissue of the ovary, hypanthium and 278
operculum, and present in the filaments and anthers (Fig. 2, C-D), consistent with a role in chemical 279
defense. Amygdalin co-localized with prunasin but was specifically restricted to the filaments and around 280
the staminal ring region (Fig. 2, C-D). In other species, cyanogenic diglycosides are suggested to be the 281
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8
transport form (Neilson et al. 2011; Selmar 1993; Selmar et al. 1996), and the results here may suggest 282
transport of cyanogenic glucosides from the hypanthium to the stamens. The role of cyanogenic glucosides 283
in flower parts has received little attention (Lai et al. 2015). Cyanogenic glucosides have previously been 284
detected in the pollen of almond flowers (Del Cueto et al. 2017; London-Shafir et al. 2003), where they are 285
hypothesized to act as a chemical deterrent to inefficient pollinators. Other specialized metabolites, such as 286
flavonol glycosides, provide a critical role in pollen development, thermo tolerance and ROS protection 287
(Paupiere et al. 2014). With their multiple functions in plants, investigations into the role of cyanogenic 288
glucosides in Eucalyptus flowers would be an intriguing avenue of research. 289
Recruitment of CYP706C55 involves an additional free nitrile intermediate in prunasin synthesis 290
We have identified and characterized three CYPs and an UGT from E. cladocalyx catalyzing the formation of 291
prunasin. Similar to other known cyanogenic glucoside biosynthetic pathways, the first step of prunasin 292
biosynthesis in E. cladocalyx is catalyzed by a multifunctional CYP79 that converts an amino acid into an 293
aldoxime. The following conversion of the aldoxime into a cyanohydrin requires two CYPs in E. cladocalyx, 294
instead of a single multifunctional CYP. CYP706C55 converts phenylacetaldoxime into phenylacetonitrile, 295
which is subsequently hydroxylated by CYP71B103 to form mandelonitrile. This is in contrast to the well 296
characterized dhurrin biosynthesis in S. bicolor, where CYP71E1 catalyzes a rearrangement of (E)-p-297
hydroxyphenylacetaldoxime to (Z)-p-hydroxyphenylacetaldoxime, then a dehydration of (Z)-p-298
hydroxyphenylacetaldoxime to p-hydroxyphenylacetonitrile followed by a C-hydroxylation resulting in p-299
hydroxymandelonitrile (Bak et al. 1998; Clausen et al. 2015; Kahn et al. 1997; Kahn et al. 1999). In prunasin-300
producing Prunus species the conversion of phenylacetaldoxime to mandelonitrile is likewise catalyzed by a 301
single CYP71 (Yamaguchi et al. 2014). The small amount of prunasin observed from N. benthamiana leaves 302
expressing CYP79A125, CYP706C55 and UGT85A59 could imply that an endogenous N. benthamiana 303
enzyme can hydroxylate phenylacetonitrile or that CYP706C55 has minor hydroxylation activity. However, 304
mandelonitrile was not observed as a product in microsomes containing CYP79A125 and CYP706C55. 305
The involvement of an extra CYP in prunasin biosynthesis in E. cladocalyx supports the hypothesis that 306
cyanogenic glucoside biosynthesis has evolved independently in several plant lineages. This hypothesis is 307
exemplified by the identification and characterization of L. japonicus CYP736A2 in lotaustralin and linamarin 308
biosynthesis (Takos et al. 2011). Differences in the biosynthesis of hydrogen cyanide based defenses are 309
also known from outside the plant kingdom. In 2010, it was shown that cyanogenic glucoside biosynthesis 310
in plants and insects evolved independently; in the burnet moth (Zygaena filipendulae), linamarin and 311
lotaustralin are produced by two CYPs (CYP405A2 and CYP332A3) and a glucosyl transferase (UGT33A1) 312
(Jensen et al. 2011). The number of enzymes required for production of the cyanohydrin may also differ in 313
insects. The millipede Chamberlinius hualienensis produces mandelonitrile as a precursor substrate for its 314
hydrogen cyanide based defense, and recently a CYP (CYP320B1) was shown to hydroxylate 315
phenylacetonitrile to form mandelonitrile (Yamaguchi et al. 2017). This function is similar to that of 316
CYP71B103 reported here and indicates that the production of α-hydroxynitriles for hydrogen cyanide 317
defense in some insects might also involve three CYPs. 318
The three-CYP-system in prunasin biosynthesis in E. cladocalyx presented here comprises an additional 319
intermediate that needs to be channeled between enzymes for production of prunasin compared to the 320
two-CYP-system in other cyanogenic species. Interestingly, the volatile intermediate phenylacetonitrile is 321
produced and released in some plant species in response to herbivory. For example, production of 322
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herbivore-induced volatiles including phenylacetonitrile has been reported for western balsam poplar 323
(Populus trichocarpa) (Irmisch et al. 2013), black poplar (P. nigra) (McCormick et al. 2014) and giant 324
knotweed (Fallopia sachalinensis) (Noge et al. 2011). It can be speculated whether some Eucalyptus species 325
might produce and release herbivore-induced nitriles. To our knowledge, however, emission of these 326
volatile compounds has not been reported for Eucalyptus. 327
Interestingly, CYPs from different families have acquired the ability to produce phenylacetonitrile from 328
phenylacetaldoxime. In E. cladocalyx, CYP706C55 from the CYP706 family catalyzes this reaction, whereas 329
P. trichocarpa and F. sachalinensis possess CYPs belonging to the large and functionally diverse CYP71 330
family that convert phenylacetaldoxime into phenylacetonitrile (Irmisch et al. 2014; Yamaguchi et al. 2016) 331
(Fig. 5, Supplemental Table S1). Phylogenetically, the E. cladocalyx CYP71B103 that hydroxylates 332
phenylacetonitrile group together with the P. trichocarpa CYP71s. These examples of functional diversity 333
within CYP families, together with the examples of independent evolution of cyanogenic glucoside 334
biosynthesis in plants, suggest that it is sometimes necessary to move away from phylogeny for 335
identification of CYP enzymes involved in the biosynthesis of interest. In contrast, the reactions catalyzed 336
by the CYP79 family are more conserved as they all convert an amino acid into its corresponding oxime 337
(Sørensen et al. 2018). 338
CYP706C55 catalyzes an atypical CYP reaction 339
CYP706C55 was identified as the second enzyme in the prunasin biosynthetic pathway in E. cladocalyx. 340
Three CYP706 members from other plant species have previously been functionally characterized and 341
demonstrated to catalyze oxygenation reactions: CYP706B1 from cotton (Gossypium arboruem L.) (Luo et 342
al. 2001), CYP706M1 from Alaskar cedar (Callitropsis nootkatensis), and a CYP706X from Erigeron 343
breviscapus (Liu et al. 2018). In contrast, CYP706C55 catalyzes an unusual CYP reaction, which is the 344
dehydration of phenyacetaldoxime to phenylacetonitrile. Although this is an unusual CYP reaction, CYP-345
catalyzed dehydration of an oxime to its corresponding nitrile have been characterized before for human 346
CYP3A4 (Boucher et al. 1994), Arabidopsis thaliana CYP71A13 (Nafisi et al. 2007), P. trichocarpa 347
CYP71B40v3 and CYP71B41v2 (Irmisch et al. 2014), and F. sachalinensis CYP71AT96 (Yamaguchi et al. 2016). 348
Dehydration of an aldoxime is also one of the partial reactions catalyzed by the multifunctional CYP71E1 in 349
dhurrin biosynthesis in sorghum as discussed above. Nonetheless, if CYP71E1 was administered with p-350
hydroxyphenylacetaldoxime in the absence of cytochrome P450 oxidoreductase (POR) and NAPDH, the 351
reaction resulted in accumulation of p-hydroxyphenylacetonitrile (Bak et al. 1998). 352
Exogenous NADPH and POR are not necessarily needed in in vitro assays for CYP71A13 and CYP71B41v2 to 353
catalyze the formation of indole-3-acetacetonitrile and phenylacetonitrile, respectively (Irmisch et al. 2014; 354
Nafisi et al. 2007). Even though POR may not be required for CYP706C55 catalysis, it has been shown that a 355
reducing environment is needed for CYP catalyzed dehydration of oximes (Boucher et al. 1994; DeMaster et 356
al. 1992; Hart-Davis et al. 1998). A reducing environment established by, for example, addition of NADPH or 357
dithionite to an assay will bring the heme group of the CYP to the Fe(II) state. This enables binding of the 358
aldoxime nitrogen to the heme, which allows for a charge transfer from Fe(II) to the aldoxime C=N bond 359
favoring elimination of the hydroxy group (Boucher et al. 1994; Hart-Davis et al. 1998). 360
Regulation of prunasin biosynthesis 361
Prunasin accumulation and gene expression were investigated in 4-, 7- and 10-month-old E. cladocalyx 362
seedlings (Fig. 6). Overall, biological replicates showed a large variation in expression of the pathway genes. 363
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Likewise, a large variation in prunasin content was also observed. A great variation in prunasin levels was to 364
be expected from the eight individuals as studies of a natural population of adult E. cladocalyx also showed 365
great variation with a difference of two orders of magnitude in hydrogen cyanide potential detected 366
(Gleadow and Woodrow 2000a). The expression pattern of the pathway genes in apical tips, expanding and 367
expanded leaves in 4-month-old plants showed less decrease with leaf age than expected based on the 368
observed pattern of prunasin accumulation. However, most plants showed the highest expression of the 369
CYPs in apical tips and expanding leaves at all three time points and the expression was found to correlate. 370
In contrast, the expression of UGT85A59 did not correlate with any of the CYPs. Similar to these findings, 371
expression levels of the two CYPs in cyanogenic glucoside biosynthesis in L. japonicus both decreased with 372
leaf age, and expression of the UGTs, which catalyze glucosylation of the cyanohydrins, did not followed the 373
CYP pattern (Takos et al. 2011). CYP79A125 was the lowest expressed pathway gene and showed the 374
largest relative variation between leaf types (Fig. 6), which may indicate that the first committed step in 375
prunasin biosynthesis controls the overall flux through the pathway. Similarly, the catalytic activity of 376
CYP79A1 constitutes the rate limiting step in dhurrin biosynthesis in sorghum (Busk and Møller 2002; 377
Nielsen et al. 2016). 378
Glucosylation by UGT85A59 results in prunasin formation 379
Transient expression of UGT85A59 in N. benthamiana showed that UGT85A59 catalyzes glucosylation of 380
the cyanohydrin, resulting in prunasin formation. Consistent with the function of stabilizing the labile 381
cyanohydrin to avoid toxic release of hydrogen cyanide, UGT85A59 was the highest expressed pathway 382
gene at most time points (Fig. 6). Since the diglucoside amygdalin was detected in E. cladocalyx metabolite 383
extracts (Fig. 1) but not upon transient expression of UGT85A59 in N. benthamiana, an additional UGT 384
remains to be identified that can catalyze a β(1→6)-O glycosylation of prunasin to yield amygdalin. In other 385
cyanogenic plant species, UGT85 members catalyze a mono-glucosylation of the cyanohydrins resulting in 386
the corresponding cyanogenic glucoside (Franks et al. 2008; Jones et al. 1999; Kannangara et al. 2011; 387
Takos et al. 2011). In contrast, less is known about UGTs that catalyze the addition of a second sugar. 388
Recently, two glucosyltransferases, UGT94AF1 and UGT94F2, were shown to glucosylate prunasin to yield 389
amygdalin in almond (Thodberg et al. 2018), and it can be speculated that a UGT94 also catalyzes the 390
glucosylation of prunasin in E. cladocalyx. 391
Conclusion 392
Our current study has characterized cyanogenic glucoside content and prunasin biosynthesis in 393
E. cladocalyx. The monoglucoside prunasin is the major cyanogen in all tissues, although significant levels of 394
the diglucoside amygdalin were detected in the reproductive organs. Until now, all characterized 395
biosynthetic pathways of cyanogenic glucosides in higher plants consist of two CYP-catalyzed reactions 396
followed by a final glucosylation reaction. Here, we show by biochemical characterization that prunasin 397
production in E. cladocalyx is catalyzed by three CYPs from different families, and a glucosyltransferase. 398
Notably, the second biosynthetic step is catalyzed by a CYP706, a CYP family not previously reported to 399
participate in the biosynthesis of cyanogenic glucosides. This finding represents a unique example of 400
convergent evolution in the biosynthesis of cyanogenic glucosides in plants. 401
Material and Methods 402
Plant material 403
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Eucalyptus cladocalyx (Sugar Gum) seeds from a single maternal tree were purchased from CSIRO 404
Australian Tree Seed Centre (Clayton, Australia). Seedlings for the ontogenetic study were germinated in 405
the glasshouse at the University of Copenhagen on the 24th of August 2013 and grown at a minimum 22°C 406
during day (10 h light) and a minimum 19°C at night and harvested 4-, 7- and 10-months after sowing (110, 407
215 and 285 days after sowing, respectively). At each time point, eight biological replicates were sampled 408
and used for metabolite and RNA extraction. Plant material for transcriptomic sequencing were likewise 409
grown in glass houses at the University of Copenhagen. Apical tips from six individual 8-month-old 410
E. cladocalyx seedlings were harvested, combined and snap frozen in liquid nitrogen. Seedlings for MALDI-411
MSI imaging were germinated in the glasshouse at the University of Melbourne on September 10, 2014 and 412
were grown at an average temperature of 23.3 ± 1.3°C during day and 19.6 ± 1.5°C at night. E. cladocalyx 413
expanded adult leaves, immature and mature flower buds, flowers and young fruit were harvested from 414
three trees growing at the University of Melbourne Parkville Campus (37.7964° S, 144.9612° E, January 415
2015), the Royal Botanic Gardens (37.8304° S, 144.9796° E, February 2015), and from the University of 416
Melbourne Creswick Campus (37.4221° S, 143.8992° E, February 2015). Samples were embedded and 417
frozen on site for MALDI-MSI analysis. Samples for LC-MS were frozen in liquid nitrogen and stored at −80°C 418
until extraction. 419
Metabolite extraction and Liquid Chromatography Mass Spectrometry (LC-MS) 420
Metabolites from E. cladocalyx (15-50 mg homogenized tissue) were extracted with cold aqueous 80% 421
MeOH. Leaf metabolites from infiltrated N. benthamiana plants expressing different combinations of gene 422
candidates were extracted with cold aqueous 85% MeOH from leaf discs (1.5 cm in diameter) harvested 5 d 423
after infiltration. All plant tissue was incubated on ice in cold MeOH for 5 minutes and extracts were 424
subsequently centrifuged (3 min, 10,000 g, 4°C) to sediment plant tissue. Extracts were diluted 5 times in 425
MilliQ water and filtered through a Durapore membrane (22 μm pore size, Merck Millipore) before 426
injection into an Agilent 1100 Series LC system coupled to a Bruker HCT-Ultra ion trap mass spectrometer 427
with an electrospray ionization source run in positive mode. Metabolites were separated on a Zorbax SB-428
C18 column (2.1 x 50 mm, 1.8 µm, Agilent) at 35°C applying a flow rate of 0.2 mL min-1. The mobile phase A 429
consisted of 0.1% (v/v) HCOOH and 50 µM NaCl and phase B consisted of 0.1% HCOOH in MeCN. The first 430
interval was 0-0.5 min isocratic with 2% B followed by two consecutive linear gradients: 0.5-7.5 min, 2-40% 431
B and 7.5-8.5 min, 40-90% B, and a second isocratic interval 8.5-11.5 min, 90% B. The mobile phase was 432
returned to 2% B from 11.5-18 min. The flow rate was raised to 0.3 mL min-1 in the interval 11.5-13.5 min. 433
LC-MS data was analyzed using Bruker Data Analysis 4.0 software. 434
MALDI-MSI and sample preparation 435
MALDI-MSI was carried out according to (Schmidt et al. 2018b). In short, the first fully expanded leaf of 436
E. cladocalyx seedlings (aged 139 DAS), fully expanded leaves from adult trees, and flower buds were 437
embedded in denatured albumin (boiled egg-white) and gently frozen over a bath of liquid nitrogen. 438
Albumin embedded tissue was cryosectioned (30 µm) (Leica CM3050 S cryostat, Leica Microsystems, 439
Wetzler, Germany), mounted onto double-sided carbon tape attached to glass slides and freeze-dried 440
overnight. 2,5-Dihydroxybenzoic acid (DHB) was used as the matrix and sublimed onto tissue sections using 441
a custom-built sublimation apparatus. MS images were acquired in positive ion mode using a Bruker SolariX 442
XR 7-Tesla Hybrid ESI/MALDI-FT-ICR-MS (Bruker Daltonik, Bremen, Germany). 443
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A mass range of 100-2000 m/z was employed with the instrument set to broadband mode with a time 444
domain for acquisition of 2M providing an estimated resolving power of 130,000 at m/z 400. The laser was 445
set to 30-45% power using the minimum spot size (laser spot size approximately 10 × 15 µm), smart-walk 446
selected and random raster enabled resulting in ablation spots of approximately 35-40 µm in diameter, a 447
total 1500-2000 shots were fired per spectra at a frequency of 2 kHz within a 40 × 40 µm array. Optical 448
images of tissue sections were acquired using an Epson Photosmart 4480 flatbed scanner using a minimum 449
setting of 4800 d.p.i. Optical images are presented as an inverted image, generated in Adobe Photoshop 450
CS2 (Adobe). The data were analyzed using Compass FlexImaging 4.1 (Bruker), data was normalized using 451
RMS normalization and individual ion images were scaled as a percentage of maximum signal intensity to 452
enhance visualization. Potassium adducts of prunasin ([M + K]+ m/z 334.0691, calculated 334.0687, 1.2 ppm 453
error) and amygdalin ([M + K]+ m/z 496.1202, calc. 496.1216, 2.6 ppm error) were compared to authentic 454
standards, spotted and dried onto a separate glass slide. 455
Characterization of the E. cladocalyx cyanogenic glucoside biosynthetic system 456
To test the substrate, product and biosynthetic capacity, E. cladocalyx leaves of different developmental 457
stages, newly emerged apical tips, expanding and expanded leaves were harvested from 5-month-old 458
seedlings (biological duplicates) and incubated in L-[14C(U)]-phenylalanine (1.25 mCi, 321 mCi mmol-1; 459
Amersham Biosciences, GE Healthcare, England) and NADPH (0.1 mM) in a total volume of 165 μL for 12 h 460
at room temperature. At the end of incubation, cyanogenic glucosides were extracted in boiling MeOH 461
(80%, 1.5 mL, 5 min), defatted with two extractions using pentane (700 μL), filtered (0.22 µm low-binding 462
Durapore membrane, Millipore, United States), and 5 μL aliquots were spotted onto a TLC plate (Silica 463
gel60F254 0.2 mm thickness, Merck, Germany), which was developed in EtOAc:HOAc:MeOH:H2O (16:5:5:2, 464
v/v/v/v). Radioactively labeled cyanogenic glucosides were visualized using a STORM 840 PhosporImager 465
(Molecular Dynamics, United States) and compared to the position of an unlabeled, co-applied prunasin 466
standard (Møller et al. 2016) visualized by UV absorption. 467
RNA extraction 468
Total RNA was extracted from E. cladocalyx leaves (apical tips, expanding and expanded leaves) at three 469
different ages in biological triplicates using the SpectrumTM Plant Total RNA Kit (Sigma) according to the 470
manufacturer’s instruction with a few modifications: approximately 20 mg homogenized tissue was used 471
for extraction and centrifugation was carried out at 4°C. DNAse treatment was performed using RNAse-free 472
DNAse I from Omega Bio-tek. The integrity of RNA was verified on an Agilent 2100 Bioanalyzer instrument 473
using a RNA 6000 Nano Kit (Agilent Technologies) according to the manufacturer’s instructions and quantity 474
was estimated using a NanoDrop ND-1000 spectrophotometer (Saveen Werner, Sweden). 475
cDNA synthesis and quantitative PCR 476
cDNA was synthesized from 1.5 μg RNA using SuperScript IV VILO Master Mix (Invitrogen) according to the 477
manufacturer’s instructions. The cDNA was diluted 30 times and 4 μL was used as template in the qPCR 478
reactions (total volume 10 μL) using SeniFAST SYBR® No-ROX Kit (Bioline) and gene specific primers (final 479
concentration: 0.4 μM). Reactions were carried out in technical triplicates and triplicate non-template 480
controls were included for every primer pair. A serial dilution from a pool of cDNA was also included for all 481
primer pairs to correct for primer efficiency. Reactions were carried out on a CFX384 Touch Real-Time PCR 482
Detection System (Bio-Rad) using two-step cycling parameters: 95°C for 2 min, followed by 45 cycles of 483
95°C for 5 sec and then 60°C for 20 sec. Melt curve analysis was performed by gradually increasing the 484
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temperature from 65°C to 95°C with 0.5°C raises. Data was analyzed using Bio-Rad CFX Manager 3.1 and 485
qbase+ version 3.1. Eight candidate reference genes previously used for gene expression analysis in 486
Eucalyptus species were selected from literature and primers were designed to match nucleotide 487
sequences from our transcriptome (Supplemental Table S2. Eight candidate reference genes were tested 488
for stability on 10 different samples using geNorm (Vandesompele et al. 2002). tRNA and MDH showed the 489
highest expression stability (Supplemental Fig. S4) and were thus used to normalize the expression of the 490
prunasin pathway genes. Primers specific for prunasin pathway transcripts are listed in Supplemental Table 491
S3. Normalized relative quantities were calculated according to Hellemans et al. (2007) by setting Cqreference 492
to 0. 493
Transcriptome analysis 494
RNA extracted from apical tips of E. cladocalyx was sent for transcriptomic sequencing (Hiseq2500, 100bp 495
paired-end) by Macrogen Inc. (Seoul, Republic of Korea). The transcriptome was de novo assembled, 496
functionally classified and expression levels were quantified by Sequentia Biotech (Bellaterra, Spain). In 497
brief, reads were quality checked and low quality reads were removed using Trimmomatic (v 0.33) (Bolger 498
et al. 2014) with a minimum length setting of 30 bp and a minimum quality score of 25. The high quality 499
reads were de novo assembled using the Trinity pipeline (Haas et al. 2013). Transcripts were translated 500
using Transdecoder with a minimum length of 50 amino acids and annotated by two different approaches: 501
by a BLAST search against a database of A. thaliana amino acid sequences and gene ontology (GO) 502
annotated using the InterproScan software (v 5.13.52.0) (Jones et al. 2014). To quantify the expression 503
levels, reads were mapped to the assembled transcriptome using STAR (Dobin et al. 2013) and the 504
expression levels were calculated with the software eXpress (v1.5.1) (Roberts and Pachter 2013). 505
Cloning of genes involved in prunasin biosynthesis 506
CYP79A125 was isolated from E. cladocalyx cDNA using primers that were designed based on CYP79A34 507
from E. yarraensis. CYP71B103 and UGT85A59 were isolated from E. cladocalyx cDNA using degenerate 508
primers that were designed based on the orthologous sequences in the E. grandis genome available on 509
Phytozome (Goodstein et al. 2012). Gene-specific primers with attB overhangs were subsequently used to 510
amplify the open reading frames for Gateway recombination into pDONR207 (Invitrogen). Primer 511
sequences are listed in Supplemental Table S4. CYP706C55 was ordered as a synthetic gene (GenScript) 512
with a C-terminal strep-tag. In addition, the full open reading frame of CYP706C55 was amplified from 513
cDNA. Candidate genes were cloned into the pJAM1502 expression vector (Luo et al. 2007) by Gateway 514
recombination. Candidate gene sequences in expression constructs were verified by sequencing (EZ-Seq, 515
Macrogen, The Netherlands). 516
Transient expression in Nicotiana benthamiana 517
Plasmids were introduced into Agrobacterium tumefaciens AGL1 (Lazo et al. 1991) by electroporation. 518
Electroporated cells were recovered in YEP (yeast extract peptone) media for 2 h at 28°C and selected on 519
YEP agar media containing 25 μg/mL rifampicin, 50 μg/mL carbenicillin and 50 μg/mL kanamycin. 520
Transformants were grown over night at 28°C, 225 rpm. Agrobacteria cells were harvested and re-521
suspended in MilliQ water to a final OD600 of 1. Equal volumes of agrobacteria suspensions were mixed and 522
introduced into N. benthamiana leaves (approximately 4-weeks-old) using a blunt syringe. An expression 523
construct carrying the ORF of p19 (Hearne et al. 1990) was always co-infiltrated to prevent post-524
transcriptional gene silencing (Lakatos et al. 2004; Voinnet et al. 1999). Two plants were infiltrated per 525
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14
combination and infiltrations were repeated to confirm results. After infiltration, the plants were kept in 526
the greenhouse (21°C day/19°C night) until leaf material was harvested. 527
Microsomal preparation 528
Leaves from transiently transformed N. benthamiana were harvested 5 d after infiltration. Approximately 6 529
g of leaves were homogenized with 0.1 g polyvinylpolypyrrolidone/g fresh weight and 30 mL buffer (100 530
mM Tricine (pH 7.9), 250 mM sucrose, 50 mM NaCl, 2mM DTT, 1 tablet cOmpleteTM protease inhibitor 531
cocktail (Roche) per 200 mL buffer) using a mortar and pestle at 4°C. The homogenate was filtered through 532
two layers of nylon cloth (22 μm pore size). Samples were centrifuged at 15,000 g for 15 min at 4°C. The 533
supernatant was subsequently applied to ultracentrifugation for 1 h at 164244 g at 4°C. The microsomal 534
pellets were washed in buffer and re-suspended in 200 µL re-suspension buffer (50 mM Tricine (pH 7.9), 20 535
mM NaCl, 2 mM DTT). 536
Microsomal assays 537
The assay reactions (total volume 25 uL) consisted of 10 uL microsomes, L-[14C(U)]-phenylalanine (0.25 μCi, 538
specific activity 487 mCi mmol-1, Perkin-Elmer), 1 mM NADPH and buffer (50 mM Tricine (pH 7.5), 100 mM 539
NaCl). Reaction mixtures were incubated for 30 min at 30°C, 300 rpm. The reactions were stopped by direct 540
application to a TLC plate (Silica gel 60F254 0.2 mm thickness, Merck, Germany). Substrate and products 541
were separated using a mobile phase consisting of n-pentane: EtOAc: MeOH (16:2:1, v/v/v). Migration of 542
phenylacetaldoxime, phenylacetonitrile and mandelonitrile were determined by application of unlabeled 543
authentic standard, which were visualized by their UV absorbance. Analysis of radiolabeled products was 544
carried out by exposure of the TLC plate to a Storage Phosphor Screen (GE Healthcare) for 8 d followed by 545
visualization using a Typhoon TRIO Variable Mode Imager (GE Healthcare). 546
Phylogenetic analysis 547
Named and functionally characterized CYPs from literature were subjected to phylogenetic analysis 548
together with the CYPs characterized here. Accession numbers and references are listed in Supplemental 549
Table S1. Amino acid sequences were aligned in MEGA7 (Kumar et al. 2016) using MUSCLE with the default 550
setting. A Neighbor Joining tree was generated with n = 1000 bootstrap replicates. 551
Statistical Analyses 552
Metabolite data was analyzed in SigmaPlot (ver. 13.0) using one-way ANOVA. Normality (Kolmogorov-553
Smirnov) and equal variance (Brown-Forsythe) was tested to a cutoff of P > 0.02 and P > 0.04, respectively, 554
and when assumptions were not met, the data was transformed by natural logarithm. Pearson correlation 555
was used to analyze gene expression. 556
Accession numbers 557
Sequence data for the prunasin biosynthetic genes identified in this study can be found in Genbank under 558
following accession numbers: CYP79A125 (MH974543), CYP706C55 (MH974544), CYP71B103 (MH974545) 559
and UGT85A59 (MH974546). 560
Supplemental Data 561
Supplemental Figure S1. Additional LC-MS data for prunasin production in N. benthamiana 562
Supplemental Figure S2. LC-MS data for glucosylated phenylacetaldoxime 563
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Supplemental Figure S3. LC-MS data for malonic acid derivative of prunasin 564
Supplemental Figure S4. geNorm analysis of candidate reference gene stabilities 565
Supplemental Table S1. Accession numbers and references for sequences used in the phylogenetic analysis 566
Supplemental Table S2. Primer sequences and references for tested candidate reference genes 567
Supplemental Table S3. Primer sequences used for gene expression analysis of the prunasin pathway genes 568
Supplemental Table S4. Cloning primers 569
Acknowledgements 570
The authors gratefully acknowledge Dr. Antanas Spokevicius for pre-publication access to the 571
transcriptomic results of E. cladocalyx and E. globulus. Ian Woodrow is thanked for hosting JSFZ during her 572
stay at The University of Melbourne. David Vernon is heartily thanked for his generous support of wildlife 573
research and encouragement to early career scientists. 574
575
Figure legends 576
Figure 1. Prunasin and amygdalin accumulation in E. cladocalyx. A. Prunasin (dark grey) and amygdalin 577
(light grey) content in expanded leaves from seedling and adult trees, immature and mature flower buds, 578
flowers and fruits. Bars represent mean with standard error. The low amounts of amygdalin present are 579
shown in more detail in the insert. Letters denote significance at P < 0.05 by one-way ANOVA analysis. B. 580
Structures of prunasin and amygdalin. 581
Figure 2. Localization of cyanogenic glucosides in E. cladocalyx tissue. Cross section of seedling dorsiventral, 582
A, and adult isobilateral, B, leaves prepared for matrix-assisted laser desorption ionization-mass 583
spectrometry imaging (MALDI-MSI), with corresponding ion maps of prunasin (yellow; m/z 334.0687; 584
[M+K]+) localizing to the mesophyll and vascular tissue. Longitudinal section of a flower bud, C, prepared 585
for MALDI-MSI with corresponding ion maps of prunasin and amygdalin (pink; m/z 496.1216; [M+K]+). 586
Enlarged portions of the flower bud, D, with the section overlaid are shown in the corresponding boxes 1 587
and 2. Prunasin ions distributed in the ground tissue within the hypanthium, stamens, and in the 588
operculum. Co-localization with amygdalin occurs in the filaments and around the staminal ring (indicated 589
by arrows). All images are root mean square (RMS) normalized, with internal scaling of 100% for prunasin 590
and 25% for amygdalin. Scale bar = 500 μM. Abbreviations: EG, embedded gland; PM, palisade; SM, spongy 591
mesophyll; VB, vascular bundle. 592
Figure 3. E. cladocalyx leaves of different developmental stages can synthesize prunasin from 593
phenylalanine. A. E. cladocalyx seedling. The tissues used for administration with L-[14C]-phenylalanine are 594
indicated. B. TLC plate showing the production of prunasin from L-[14C]-phenylalanine in apical tips, 1st 595
and 2nd expanding leaves and fully expanded leaves. 596
Figure 4. Prunasin biosynthesis is catalyzed by three CYPs and a UGT. A. LC-MS extracted ion 597
chromatograms for prunasin ([M+Na]+ m/z 318) of extracts from N. benthamiana leaves transiently 598
expressing candidate genes. B. Microsomes prepared from N. benthamiana leaves transiently expressing 599
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16
candidate CYP genes were assayed with 14C-phenylalanine and products were separated by TLC. C. 600
Proposed pathway for prunasin synthesis in E. cladocalyx. 601
Figure 5. Phylogenetic analysis of functionally characterized CYPs belonging to the CYP79, CYP71, CYP706 602
and CYP736 families, including members involved in cyanogenic glucoside biosynthesis (indicated by * ). 603
Phylogeny was inferred using the Neighbour-Joining method with n = 1000 bootstrap replicates. Full 604
species names, Genbank accession numbers and references are listed in Supplemental Table S1. 605
Figure 6. Prunasin accumulation and expression of the biosynthetic genes in 4, 7 and 10 months old 606
E. cladocalyx plants (n = 6-8). A. Prunasin accumulation in apical tips, expanding leaves and expanded 607
leaves. Bars represent mean +/- standard error. Letters denote significance at P < 0.05 by one-way ANOVA 608
analysis. B. Normalized gene expression of CYP79A125, CYP706C55, CYP71B103 and UGT85A59 in apical 609
tips, expanding leaves and expanded leaves. Symbols represent biological replicates (n = 3) C. Spearman 610
correlation analysis of gene expression showing co-regulation of some genes. 611
Literature cited 612
Andersen, M. D., Busk, P. K., Svendsen, I., and Møller, B. L. (2000). "Cytochromes P-450 from cassava 613 (Manihot esculenta Crantz) catalyzing the first steps in the biosynthesis of the cyanogenic 614 glucosides linamarin and lotaustralin: cloning, functional expression in Pichia pastoris, and 615 substrate specificity of the isolated recombinant enzymes." J. Biol. Chem., 275, 1966-1975. 616
Bak, S., Kahn, R. A., Nielsen, H. L., Møller, B. L., and Halkier, B. A. (1998). "Cloning of three A-type 617 cytochromes P450, CYP71E1, CYP98, and CYP99 from Sorghum bicolor (L.) Moench by a PCR 618 approach and identification by expression in Eschericia coli of CYP71E1 as a multifunctional 619 cytochrome P450 in the biosynthesis of the cyanogenic glucoside dhurrin." Plant Mol. Biol, 36, 393-620 405. 621
Bassard, J. E., Møller, B. L., and Laursen, T. (2017). "Assembly of Dynamic P450-Mediated Metabolons-622 Order Versus Chaos." Curr Mol Biol Rep, 3(1), 37-51. 623
Bjarnholt, N., Li, B., D'Alvise, J., and Janfelt, C. (2014). "Mass spectrometry imaging of plant metabolites--624 principles and possibilities." Nat Prod Rep, 31(6), 818-37. 625
Bjarnholt, N., Neilson, E. H. J., Crocoll, C., Jørgensen, K., Motawia, M. S., Olsen, C. E., Dixon, D. P., Edwards, 626 R., and Møller, B. L. (2018). "Glutathione transferases catalyze recycling of auto-toxic cyanogenic 627 glucosides in sorghum." Plant J, 94(6), 1109-1125. 628
Bolger, A. M., Lohse, M., and Usadel, B. (2014). "Trimmomatic: a flexible trimmer for Illumina sequence 629 data." Bioinformatics, 30(15), 2114-20. 630
Boucher, J.-L., Delaforge, M., and Mansuy, D. (1994). "Dehydration of Alkyl- and Arylaldoximes as a New 631 Cytochrome P450-Catalyzed Reaction: Mechanism and Stereochemical Characterization." 632 Biochemistry, 33, 7811-7818. 633
Boughton, B. A., Thinagaran, D., Sarabia, D., Bacic, A., and Roessner, U. (2016). "Mass spectrometry imaging 634 for plant biology: a review." Phytochem Rev, 15, 445-488. 635
Burchell, B., Nebert, D. W., Nelson, D. R., Bock, K. W., Iyanagi, T., Jansen, P. L. M., Lancet, D., Mulder, G. J., 636 Chowdhury, J. R., Siest, G., Tephly, T. R., and Mackenzie, P. I. (1991). "The UDP 637 Glucuronosyltransferase Gene Superfamily: Suggested Nomenclature Based on Evolutionary 638 Divergence." DNA Cell Biol, 10(7), 487-494. 639
Busk, P. K., and Møller, B. L. (2002). "Dhurrin synthesis in sorghum is regulated at the transcriptional level 640 and induced by nitrogen fertilization in older plants." Plant Physiol, 129(3), 1222-31. 641
Clausen, M., Kannangara, R. M., Olsen, C. E., Blomstedt, C. K., Gleadow, R. M., Jorgensen, K., Bak, S., 642 Motawie, M. S., and Møller, B. L. (2015). "The bifurcation of the cyanogenic glucoside and 643 glucosinolate biosynthetic pathways." Plant J, 84(3), 558-73. 644
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
17
Coppen, J. J. W. (2002). Eucalyptus: the Genus Eucalyptus London: Taylor and Francis. 645 Darbani, B., Motawia, M. S., Olsen, C. E., Nour-Eldin, H. H., Møller, B. L., and Rook, F. (2016). "The 646
biosynthetic gene cluster for the cyanogenic glucoside dhurrin in Sorghum bicolor contains its co-647 expressed vacuolar MATE transporter." Sci Rep, 6, 37079. 648
Del Cueto, J., Ionescu, I. A., Pičmanová, M., Gericke, O., Motawia, M. S., Olsen, C. E., Campoy, J. A., Dicenta, 649 F., Møller, B. L., and Sanchez-Perez, R. (2017). "Cyanogenic Glucosides and Derivatives in Almond 650 and Sweet Cherry Flower Buds from Dormancy to Flowering." Front Plant Sci, 8, 800. 651
DeMaster, E. G., Shirota, F. N., and Nagasawa, H. T. (1992). "A Beckmann-type dehydration of n-652 butyraldoxime catalyzed by cytochrome P-450." J. Org. Chem, 57, 5074-5075. 653
Dobin, A., Davis, C. A., Schlesinger, F., Drenkow, J., Zaleski, C., Jha, S., Batut, P., Chaisson, M., and Gingeras, 654 T. R. (2013). "STAR: ultrafast universal RNA-seq aligner." Bioinformatics, 29(1), 15-21. 655
Eschler, B. M., Pass, D. M., Willis, R., and Foley, W. J. (2000). "Distribution of foliar formylated 656 phloroglucinol derivatives amongst Eucalyptus species." Biochem. Syst. Ecol., 28(9), 813-824. 657
Finnemore, H., and Cox, C. B. (1928). "Cyanogenetic glucosides in Australian Plants." J. Proc. Roy. Soc. NSW, 658 62, 369-378. 659
Finnemore, H., Reichard, S. K., and Large, D. K. (1935). "Cyanogenetic glucosides in Australian plants: 660 Eucalyptus cladocalyx." J. Proc. Roy. Soc. NSW, 69, 209-214. 661
Forslund, K., Morant, M., Jørgensen, B., Olsen, C. E., Asamizu, E., Sato, S., Tabata, S., and Bak, S. (2004). 662 "Biosynthesis of the nitrile glucosides rhodiocyanoside A and D and the cyanogenic glucosides 663 lotaustralin and linamarin in Lotus japonicus." Plant Physiol, 135(1), 71-84. 664
Franks, T. K., Yadollahi, A., Wirthensohn, M. G., Huerin, J. R., Kaiser, B. N., Sedgley, M., and Ford, C. M. 665 (2008). "A seed coat cyanohydrin glucosyltransferase is associated with bitterness in almond 666 (Prunus dulcis) kernels." Funct. Plant Biol., 35(3), 236-246. 667
Franzmayr, B. K., Rasmussen, S., Fraser, K. M., and Jameson, P. E. (2012). "Expression and functional 668 characterization of a white clover isoflavone synthase in tobacco." Ann Bot, 110(6), 1291-301. 669
Gleadow, R. M., Foley, W. J., and Woodrow, I. E. (1998). "Enhanced CO2 alters the relationship between 670 photosynthesis and defence in cyanogenic Eucalyptus cladocalyx F. Muell." Plant Cell Environ, 21, 671 12-22. 672
Gleadow, R. M., Haburjak, J., Dunn, J. E., Conn, M. E., and Conn, E. E. (2008). "Frequency and distribution of 673 cyanogenic glycosides in Eucalyptus L'Herit." Phytochemistry, 69(9), 1870-4. 674
Gleadow, R. M., and Møller, B. L. (2014). "Cyanogenic glycosides: synthesis, physiology, and phenotypic 675 plasticity." Annu Rev Plant Biol, 65, 155-85. 676
Gleadow, R. M., and Woodrow, I. E. (2000a). "Polymorphism in cyanogenic glycoside content and 677 cyanogenic β-glucosidase activity in natural populations of Eucalyptus cladocalyx." Aust. J. Plant 678 Physiol., 27, 693-699. 679
Gleadow, R. M., and Woodrow, I. E. (2000b). "Temporal and spatial variation in cyanogenic glycosides in 680 Eucalyptus cladocalyx." Tree Physiol, 20(9), 591-598. 681
Gleadow, R. M., and Woodrow, I. E. (2002). "Constraints on effectiveness of cyanogenic glycoside in 682 herbivore defense." J. Chem. Ecol., 28, 1301-1313. 683
Goodger, J. Q., Choo, T. Y., and Woodrow, I. E. (2007). "Ontogenetic and temporal trajectories of chemical 684 defence in a cyanogenic eucalypt." Oecologia, 153(4), 799-808. 685
Goodger, J. Q. D., Ades, P. K., and Woodrow, I. E. (2004). "Cyanogenesis in Eucalyptus polyanthemos 686 seedlings: heritability, ontogeny and effect of soil nitrogen." Tree Physiology, 24, 681-688. 687
Goodger, J. Q. D., Gleadow, R. M., and Woodrow, I. E. (2006). "Growth cost and ontogenetic expression 688 patterns of defence in cyanogenic Eucalyptus spp." Trees, 20(6), 757-765. 689
Goodstein, D. M., Shu, S., Howson, R., Neupane, R., Hayes, R. D., Fazo, J., Mitros, T., Dirks, W., Hellsten, U., 690 Putnam, N., and Rokhsar, D. S. (2012). "Phytozome: a comparative platform for green plant 691 genomics." Nucleic Acids Res, 40(Database issue), D1178-86. 692
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
18
Hart-Davis, J., Battioni, P., Boucher, J.-L., and Mansuy, D. (1998). "New catalytic properties of iron 693 porphyrins: model systems for cytochrome P450-catalyzed dehydration of aldoximes." J. Am. 694 Chem. Soc., 120, 12524-12530. 695
Hearne, P. Q., Knorr, D. A., Hillman, B., and Morris, T. J. (1990). "The complete genome structure and 696 synthesis of infectious RNA from clones of tomato bushy stunt virus." Virology, 177(1), 141-151. 697
Hellemans, J., Mortier, G., de Peape, A., Speleman, F., and Vandesompele, J. (2007). "qBase relative 698 quantification framework and sothware for management and automated analysis of real-time 699 quantitative PCR data." Genome Biology, 8, R19. 700
Haas, B. J., Papanicolaou, A., Yassour, M., Grabherr, M., Blood, P. D., Bowden, J., Couger, M. B., Eccles, D., 701 Li, B., Lieber, M., MacManes, M. D., Ott, M., Orvis, J., Pochet, N., Strozzi, F., Weeks, N., Westerman, 702 R., William, T., Dewey, C. N., Henschel, R., LeDuc, R. D., Friedman, N., and Regev, A. (2013). "De 703 novo transcript sequence reconstruction from RNA-seq using the Trinity platform for reference 704 generation and analysis." Nat Protoc, 8(8), 1494-512. 705
Irmisch, S., Clavijo McCormick, A., Gunther, J., Schmidt, A., Boeckler, G. A., Gershenzon, J., Unsicker, S. B., 706 and Köllner, T. G. (2014). "Herbivore-induced poplar cytochrome P450 enzymes of the CYP71 family 707 convert aldoximes to nitriles which repel a generalist caterpillar." Plant J, 80(6), 1095-107. 708
Irmisch, S., McCormick, A. C., Boeckler, G. A., Schmidt, A., Reichelt, M., Schneider, B., Block, K., Schnitzler, J. 709 P., Gershenzon, J., Unsicker, S. B., and Köllner, T. G. (2013). "Two herbivore-induced cytochrome 710 P450 enzymes CYP79D6 and CYP79D7 catalyze the formation of volatile aldoximes involved in 711 poplar defense." Plant Cell, 25(11), 4737-54. 712
Jenrich, R., Trompetter, I., Bak, S., Olsen, C. E., Møller, B. L., and Piotrowski, M. (2007). "Evolution of 713 heteromeric nitrilase complexes in Poaceae with new functions in nitrile metabolism." Proc Natl 714 Acad Sci U S A, 104(47), 18848-53. 715
Jensen, N. B., Zagrobelny, M., Hjerno, K., Olsen, C. E., Houghton-Larsen, J., Borch, J., Møller, B. L., and Bak, 716 S. (2011). "Convergent evolution in biosynthesis of cyanogenic defence compounds in plants and 717 insects." Nat Commun, 2, 273. 718
Jones, P., Binns, D., Chang, H. Y., Fraser, M., Li, W., McAnulla, C., McWilliam, H., Maslen, J., Mitchell, A., 719 Nuka, G., Pesseat, S., Quinn, A. F., Sangrador-Vegas, A., Scheremetjew, M., Yong, S. Y., Lopez, R., 720 and Hunter, S. (2014). "InterProScan 5: genome-scale protein function classification." 721 Bioinformatics, 30(9), 1236-40. 722
Jones, P. R., Møller, B. L., and Høj, P. B. (1999). "The UDP-glucose:p-Hydroxymandelonitrile-O-723 Glucosyltransferase That Catalyzes the Last Step in Synthesis of the Cyanogenic Glucoside Dhurrin 724 in Sorghum bicolor." Journal of Biological Chemistry, 274(50), 35483-35491. 725
Jørgensen, K., Bak, S., Busk, P. K., Sørensen, C., Olsen, C. E., Puonti-Kaerlas, J., and Møller, B. L. (2005). 726 "Cassava plants with a depleted cyanogenic glucoside content in leaves and tubers. Distribution of 727 cyanogenic glucosides, their site of synthesis and transport, and blockage of the biosynthesis by 728 RNA interference technology." Plant Physiol, 139(1), 363-74. 729
Jørgensen, K., Morant, A. V., Morant, M., Jensen, N. B., Olsen, C. E., Kannangara, R., Motawia, M. S., Møller, 730 B. L., and Bak, S. (2011). "Biosynthesis of the cyanogenic glucosides linamarin and lotaustralin in 731 cassava: isolation, biochemical characterization, and expression pattern of CYP71E7, the oxime-732 metabolizing cytochrome P450 enzyme." Plant Physiol, 155(1), 282-92. 733
Kahn, R. A., Bak, S., Svendsen, I., Halkier, B. A., and Møller, B. L. (1997). "Isolation and Reconstitution of 734 Cytochrome P450ox and in Vitro Reconstitution of the Entire Biosynthetic Pathway of the 735 Cyanogenic Glucoside Dhurrin from Sorghum." Plant Physiol, 115, 1661-1670. 736
Kahn, R. A., Fahrendorf, T., Halkier, B. A., and Møller, B. L. (1999). "Substrate specificity of the cytochrome 737 P450 enzymes CYP79A1 and CYP71E1 involved in the biosynthesis of the cyanogenic glucoside 738 dhurrin in Sorghum bicolor (L.) Moench." Arch. Biochem. Biophys., 363, 9-18. 739
Kannangara, R., Motawia, M. S., Hansen, N. K., Paquette, S. M., Olsen, C. E., Møller, B. L., and Jørgensen, K. 740 (2011). "Characterization and expression profile of two UDP-glucosyltransferases, UGT85K4 and 741
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
19
UGT85K5, catalyzing the last step in cyanogenic glucoside biosynthesis in cassava." Plant J, 68(2), 742 287-301. 743
Koch, B. M., Sibbesen, O., Halkier, B. A., Svendsen, I., and Møller, B. L. (1995). "The primary sequence of 744 cytochrome P450tyr, the multifunctional N-hydroxylase catalyzing the conversion of L-tyrosine to 745 p-hydroxyphenylacetaldehyde oxime in the biosynthesis of the cyanogenic glucoside dhurrin in 746 Sorghum bicolor (L.) Moench." Arch. Biochem. Biophys., 323, 177-186. 747
Kulheim, C., Padovan, A., Hefer, C., Krause, S. T., Kollner, T. G., Myburg, A. A., Degenhardt, J., and Foley, W. 748 J. (2015). "The Eucalyptus terpene synthase gene family." BMC Genomics, 16, 450. 749
Kumar, S., Stecher, G., and Tamura, K. (2016). "MEGA7: Molecular Evolutionary Genetics Analysis Version 750 7.0 for Bigger Datasets." Mol Biol Evol, 33(7), 1870-4. 751
Lai, D., Pičmanová, M., Abou Hachem, M., Motawia, M. S., Olsen, C. E., Møller, B. L., Rook, F., and Takos, A. 752 M. (2015). "Lotus japonicus flowers are defended by a cyanogenic beta-glucosidase with highly 753 restricted expression to essential reproductive organs." Plant Mol Biol, 89(1-2), 21-34. 754
Lakatos, L., Szittya, G., DSilhavy, D., and Burgyán, J. (2004). "Melcular mechanism of RNA silencing 755 suppression mediated by p19 protein of tombusviruses." EMBO J., 23(4), 876-884. 756
Laursen, T., Borch, J., Knudsen, C., Bavishi, K., Torta, F., Martens, H. J., Silvestro, D., Hatzakis, N., Wenk, M. 757 R., Dafforn, T. R., Olsen, C. E., Motawia, M. S., Hamberger, B., Møller, B. L., and Bassard, J.-E. (2016). 758 "Characterization of a dynamic metabolon producing the defense compund dhurrin in sorghum." 759 Science, 354(6314), 890-893. 760
Lazo, G. R., Stein, P. A., and Ludwig, R. A. (1991). "A DNA treansformation-competent Arabidopsis library in 761 Agrobacterium." Biotechnology (N Y), 9(10), 963-967. 762
Liu, X., Cheng, J., Zhang, G., Ding, W., Duan, L., Yang, J., Kui, L., Cheng, X., Ruan, J., Fan, W., Chen, J., Long, 763 G., Zhao, Y., Cai, J., Wang, W., Ma, Y., Dong, Y., Yang, S., and Jiang, H. (2018). "Engineering yeast for 764 the production of breviscapine by genomic analysis and synthetic biology approaches." Nat 765 Commun, 9(1), 448. 766
London-Shafir, I., Shafir, S., and Eisikowitch, D. (2003). "Amygdalin in almond nectar and pollen – facts and 767 possible roles." Plant Systematics and Evolution, 238(1-4), 87-95. 768
Luo, J., Nishiyama, Y., Fuell, C., Taguchi, G., Elliott, K., Hill, L., Tanaka, Y., Kitayama, M., Yamazaki, M., Bailey, 769 P., Parr, A., Michael, A. J., Saito, K., and Martin, C. (2007). "Convergent evolution in the BAHD family 770 of acyl transferases: identification and characterization of anthocyanin acyl transferases from 771 Arabidopsis thaliana." Plant J, 50(4), 678-95. 772
Luo, P., Wang, Y.-H., Wang, G.-D., Essenberg, and Chen, X.-Y. (2001). "Molecular cloning and functional 773 identification of (+)-δ-8-hydroxylase, a cytochrome P450 mono-oxygenase (CYP706B1) of cotton 774 sesquiterpene biosynthesis." The Plant Journal, 28(1), 95-104. 775
Mackenzie, P. I., Bock, K. W., Burchell, B., Guillemette, C., Ikushiro, S.-i., Iyanagi, T., Miners, J. O., Owens, I. 776 S., and Nebert, D. W. (2005). "Nomenclature update for the mammalian UDP glycosyltransferase 777 (UGT) gene superfamily." Pharmacogenet Genomic, 15, 677-685. 778
Marsh, K. J., Kulheim, C., Blomberg, S. P., Thornhill, A. H., Miller, J. T., Wallis, I. R., Nicolle, D., Salminen, J. P., 779 and Foley, W. J. (2017). "Genus-wide variation in foliar polyphenolics in eucalypts." Phytochemistry, 780 144, 197-207. 781
McCormick, A. C., Irmisch, S., Reinecke, A., Boeckler, G. A., Veit, D., Reichelt, M., Hansson, B. S., 782 Gershenzon, J., Kollner, T. G., and Unsicker, S. B. (2014). "Herbivore-induced volatile emission in 783 black poplar: regulation and role in attracting herbivore enemies." Plant Cell Environ, 37(8), 1909-784 23. 785
Myburg, A. A., Grattapaglia, D., Tuskan, G. A., Hellsten, U., Hayes, R. D., Grimwood, J., Jenkins, J., Lindquist, 786 E., Tice, H., Bauer, D., Goodstein, D. M., Dubchak, I., Poliakov, A., Mizrachi, E., Kullan, A. R., Hussey, 787 S. G., Pinard, D., van der Merwe, K., Singh, P., van Jaarsveld, I., Silva-Junior, O. B., Togawa, R. C., 788 Pappas, M. R., Faria, D. A., Sansaloni, C. P., Petroli, C. D., Yang, X., Ranjan, P., Tschaplinski, T. J., Ye, 789 C. Y., Li, T., Sterck, L., Vanneste, K., Murat, F., Soler, M., Clemente, H. S., Saidi, N., Cassan-Wang, H., 790 Dunand, C., Hefer, C. A., Bornberg-Bauer, E., Kersting, A. R., Vining, K., Amarasinghe, V., Ranik, M., 791
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
20
Naithani, S., Elser, J., Boyd, A. E., Liston, A., Spatafora, J. W., Dharmwardhana, P., Raja, R., Sullivan, 792 C., Romanel, E., Alves-Ferreira, M., Kulheim, C., Foley, W., Carocha, V., Paiva, J., Kudrna, D., 793 Brommonschenkel, S. H., Pasquali, G., Byrne, M., Rigault, P., Tibbits, J., Spokevicius, A., Jones, R. C., 794 Steane, D. A., Vaillancourt, R. E., Potts, B. M., Joubert, F., Barry, K., Pappas, G. J., Strauss, S. H., 795 Jaiswal, P., Grima-Pettenati, J., Salse, J., Van de Peer, Y., Rokhsar, D. S., and Schmutz, J. (2014). "The 796 genome of Eucalyptus grandis." Nature, 510(7505), 356-62. 797
Møller, B. L. (2010). "Functional diversifications of cyanogenic glucosides." Curr Opin Plant Biol, 13(3), 338-798 47. 799
Møller, B. L., Olsen, C. E., and Motawia, M. S. (2016). "General and Stereocontrolled Approach to the 800 Chemical Synthesis of Naturally Occurring Cyanogenic Glucosides." J Nat Prod, 79(4), 1198-202. 801
Nafisi, M., Goregaoker, S., Botanga, C. J., Glawischnig, E., Olsen, C. E., Halkier, B. A., and Glazebrook, J. 802 (2007). "Arabidopsis cytochrome P450 monooxygenase 71A13 catalyzes the conversion of indole-3-803 acetaldoxime in camalexin synthesis." Plant Cell, 19(6), 2039-52. 804
Neilson, E. H. (2012). Characterisation of Cyanogenic Glucoside Synthesis in Eucalyptus, PhD thesis, 805 University of Melbourne. 806
Neilson, E. H., Goodger, J. Q., Motawia, M. S., Bjarnholt, N., Frisch, T., Olsen, C. E., Møller, B. L., and 807 Woodrow, I. E. (2011). "Phenylalanine derived cyanogenic diglucosides from Eucalyptus camphora 808 and their abundances in relation to ontogeny and tissue type." Phytochemistry, 72(18), 2325-34. 809
Nelson, D. N. (2009). "The Cytochrome P450 Homepage." Hum Genomics, 4(1), 59-65. 810 Nielsen, L. J., Stuart, P., Pičmanová, M., Rasmussen, S., Olsen, C. E., Harholt, J., Møller, B. L., and Bjarnholt, 811
N. (2016). "Dhurrin metabolism in the developing grain of Sorghum bicolor (L.) Moench investigated 812 by metabolite profiling and novel clustering analyses of time-resolved transcriptomic data." BMC 813 Genomics, 17(1), 1021. 814
Noge, K., Abe, M., and Tamogami, S. (2011). "Phenylacetonitrile from the giant knotweed, Fallopia 815 sachalinensis, infested by the Japanese beetle, Popillia japonica, is induced by exogenous methyl 816 jasmonate." Molecules, 16(8), 6481-8. 817
Padovan, A., Keszei, A., Külheim, C., and Foley, W. J. (2014). "The evolution of foliar terpene diversity in 818 Myrtaceae." Phytochem Rev, 13(3), 695-716. 819
Paupiere, M. J., van Heusden, A. W., and Bovy, A. G. (2014). "The metabolic basis of pollen thermo-820 tolerance: perspectives for breeding." Metabolites, 4(4), 889-920. 821
Pičmanová, M., Neilson, E. H., Motawia, M. S., Olsen, C. E., Agerbirk, N., Gray, C. J., Flitsch, S., Meier, S., 822 Silvestro, D., Jørgensen, K., Sanchez-Perez, R., Møller, B. L., and Bjarnholt, N. (2015). "A recycling 823 pathway for cyanogenic glycosides evidenced by the comparative metabolic profiling in three 824 cyanogenic plant species." Biochem J, 469(3), 375-89. 825
Rhoades, D. F. (1979). "Evolution of plant chemical defense against herbivores.", in G. A. Rosenthal and D. 826 H. Janzen, (eds.), Herbivores: their interaction with secondary plant metabolites. New York: 827 Academic Press, pp. 3-54. 828
Roberts, A., and Pachter, L. (2013). "Streaming fragment assignment for real-time analysis of sequencing 829 experiments." Nat Methods, 10(1), 71-3. 830
Schmidt, F. B., Cho, S. K., Olsen, C. E., Yang, S. W., Møller, B. L., and Jørgensen, K. (2018a). "Diurnal 831 regulation of cyanogenic glucoside biosynthesis and endogenous turnover in cassava." Plant Direct, 832 2(2), e00038. 833
Schmidt, F. B., Heskes, A. M., Thinagaran, D., Møller, B. L., Jørgensen, K., and Boughton, B. A. (2018b). 834 "Mass Spectrometry Based Imaging of Labile Glucosides in Plants." Front Plant Sci, 9, 892. 835
Selmar, D. (1993). "Transport of cyanogenic glucosides: linustatin uptake by Hevea cotyledons." Planta, 836 191(2), 191-199. 837
Selmar, D., Irandoost, Z., and Wray, V. (1996). "Dhurrin-6'-glucoside, a cyanogenic diglucoside from 838 Sorghum bicolor." Phytochemistry, 43(3), 569-572. 839
Selmar, D., Lieberel, R., and Biehl, B. (1988). "Mobilization and Utilization of Cyanogenic Glucosides. The 840 Linustatin Pathway." Plant Physiol, 86, 711-716. 841
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
21
Spokevicius, A. V., Tibbits, J., Rigault, P., Nolin, M. A., Muller, C., and Merchant, A. (2017). "Medium term 842 water deficit elicits distinct transcriptome responses in Eucalyptus species of contrasting 843 environmental origin." BMC Genomics, 18(1), 284. 844
Sørensen, M., Neilson, E. H. J., and Møller, B. L. (2018). "Oximes: Unrecognized Chameleons in General and 845 Specialized Plant Metabolism." Mol Plant, 11(1), 95-117. 846
Takos, A. M., Knudsen, C., Lai, D., Kannangara, R., Mikkelsen, L., Motawia, M. S., Olsen, C. E., Sato, S., 847 Tabata, S., Jørgensen, K., Møller, B. L., and Rook, F. (2011). "Genomic clustering of cyanogenic 848 glucoside biosynthetic genes aids their identification in Lotus japonicus and suggests the repeated 849 evolution of this chemical defence pathway." Plant J, 68(2), 273-86. 850
Thodberg, S., Cueto, J. D., Mazzeo, R., Pavan, S., Lotti, C., Dicenta, F., Neilson, E. H., Møller, B. L., and 851 Sánchez-Pérez, R. (2018). "The bedrock of almond bitterness: the amygdalin pathway in almond 852 (Prunus dulcis)." Plant Physiology, accepted manuscript. 853
Tian, L., and Dixon, R. A. (2006). "Engineering isoflavone metabolism with an artificial bifunctional enzyme." 854 Planta, 224(3), 496-507. 855
Ting, H. M., Wang, B., Ryden, A. M., Woittiez, L., van Herpen, T., Verstappen, F. W., Ruyter-Spira, C., 856 Beekwilder, J., Bouwmeester, H. J., and van der Krol, A. (2013). "The metabolite chemotype of 857 Nicotiana benthamiana transiently expressing artemisinin biosynthetic pathway genes is a function 858 of CYP71AV1 type and relative gene dosage." New Phytol, 199(2), 352-66. 859
Vandesompele, J., de Preter, K., Pattyn, F., Poppe, B., van Roy, N., de Paepe, A., and Speleman, F. (2002). 860 "Accurate normalization of real-time quantitative RT-PCR data by geometric averaging of multiple 861 internal control genes." Genome Biology, 3(7), research0034.1–research0034.11. 862
Vetter, J. (2017). "Plant Cyanogenic Glycosides", in P. Gopalakrishnakone, C. R. Carlini, and R. Ligabue-863 Braun, (eds.), Plant Toxins. Springer, pp. 287-317. 864
Voinnet, O., Pinto, Y. M., and Baulcombe, D. C. (1999). "Suppression of gene silencing: A general strategy 865 used by diverse DNA and RNA viruses of plants." Proc Natl Acad Sci U S A, 96(24), 14147-14152. 866
Yamaguchi, T., Kuwahara, Y., and Asano, Y. (2017). "A novel cytochrome P450, CYP3201B1, is involved in 867 (R)-mandelonitrile biosynthesis in a cyanogenic millipede." FEBS Open Bio, 7(3), 335-347. 868
Yamaguchi, T., Noge, K., and Asano, Y. (2016). "Cytochrome P450 CYP71AT96 catalyses the final step of 869 herbivore-induced phenylacetonitrile biosynthesis in the giant knotweed, Fallopia sachalinensis." 870 Plant Mol Biol, 91(3), 229-39. 871
Yamaguchi, T., Yamamoto, K., and Asano, Y. (2014). "Identification and characterization of CYP79D16 and 872
CYP71AN24 catalyzing the first and second steps in L‑phenylalanine‑derived cyanogenic glycoside 873 biosynthesis in the Japanese apricot, Prunus mume Sieb. et Zucc." Plant Mol Biol, 86, 215-223. 874
875
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Figure 1. Prunasin and amygdalin accumulation in E. cladocalyx. A. Prunasin (dark grey) and amygdalin (light grey) content in expanded leaves from seedling and adult trees, immature and mature flower buds, flowers and fruits. Bars represent mean with standard error. The low amounts of amygdalin present are shown in more detail in the insert. Letters denote significance at P < 0.05 by one-way ANOVA analysis. B. Structures of prunasin and amygdalin.
Se
ed
lin
g l
ea
f
Ad
ult
le
af
Imm
atu
re f
low
erb
ud
Ma
ture
flo
we
rbu
d
Flo
we
r
Fru
it
ug m
gD
W-1
0
10
20
30
40
50
60
70
80
90
100Prunasin
Amygdalin
0.0
0.5
5.0
10.0B A Prunasin
Amygdalin
ac
a
c
ab
bc
ab
ac
c
bc
ab
a a
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Bo
x 1
. B
ox
2.
Filament
Filament
Anther
Operculum
EG
1.
2.
Prunasin Amygdalin Overlay C
D
B
A
Placenta
Operculum
Stamens (detached)
1.
2.
Ovules
Pedicle
Staminal ring
Upper Epidermis
PM
PM
SM
VB
EG
VB Cuticle
Epidermis
Lower Epidermis
Prunasin
Figure 2. Localization of cyanogenic glucosides in Eucalyputs cladocalyx tissue. Cross section of seedling dorsiventral, A, and adult isobilateral, B, leaves prepared for matrix-assisted laser desorption ionisation-mass spectrometry imaging (MALDI-MSI), with corresponding ion maps of prunasin (yellow; m/z 334.0687; [M+K]+) localizing to the mesophyll and vascular tissue. Longitudinal section of a flower bud C prepared for MALDI-MSI with corresponding ion maps of prunasin and amygdalin (pink; m/z 496.1216; [M+K]+). Enlarged portions of the flower bud, D, with the section overlaid are shown in the corresponding boxes 1 and 2. Prunasin ions distributed in the ground tissue within the hypanthium, stamens, and in the operculum. Co-localisation with amygdalin occurs in the filaments and around the staminal ring (indicated by arrows). All images root mean square (RMS) normalized, with internal scaling of 100% for prunasin and 25% for amydgalin. Scale bar = 500 µM. Abbreviations: EG, embedded gland; PM, palisade; SM, spongy mesophyll; VB, vascular bundle.
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Figure 3. E. cladocalyx leaves of different developmental stages can synthesize prunasin from phenylalanine. A. E. cladocalyx seedling. The tissues used for administration with L-[14C]-phenylalanine are indicated. B. TLC plate showing the production of prunasin from L-[14C]-phenylalanine in apical tips, 1st and 2nd expanding leaves and fully expanded leaves.
Prunasin
Phenylalanine
Tip
1st expanding leaf
2nd expanding leaf
Expanded leaf
B A
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Figure 4. Prunasin biosynthesis is catalyzed by three CYPs and a UGT. A. LC-MS extracted ion chromatograms for prunasin ([M+Na]+ m/z 318) of extracts from N. benthamiana leaves transiently expressing candidate genes. B. Microsomes prepared from N. benthamiana leaves transiently expressing candidate CYP genes were assayed with 14C-phenylalanine and products were separated by TLC. C. Proposed pathway for prunasin synthesis in E. cladocalyx.
A
phenylacetonitrile
phenylacetaldoxime
CYP79A125 + + + + + + +
+ - - -
-
B
- - -
mandelonitrile
benzoic acid
CYP706C55
CYP71B103
C
Phenylalanine
Prunasin
Mandelonitrile
Phenylacetonitrile
Phenylacetaldoxime
CYP79A125
CYP706C55
CYP71B103
UGT85A59
CYP706C55 + CYP71B103 + UGT85A59
CYP79A125 + CYP706C55 + CYP71B103 + UGT85A59
Inte
nsity
3x10
8 (E
IC m
/z 3
18
)
Negative control
Prunasin standard
CYP79A125 + CYP71B103 + UGT85A59
CYP79A125 + CYP706C55 + UGT85A59
CYP79A125 + CYP706C55 + CYP71B103
4 6 Time [min]
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Figure 5. Phylogenetic analysis of functionally characterized CYPs belonging to the CYP79, CYP71, CYP706 and CYP736 families, including members involved in cyanogenic glucoside biosynthesis (indicated by * ). Phylogeny was inferred using the Neighbour-Joining method with n = 1000 bootstrap replicates. Full species names, Genbank accession numbers and references are listed in Supplemental Table S1.
CY
P71A
V3 L
. sativa
CYP79E1 T. maritima
0.10
* *
* *
* *
*
*
*
*
*
*
*
*
*
*
*
* *
* *
*
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CYP71B103
No
rma
lize
d R
ela
tive
ex
pre
ss
ion
0
2
4
6
8
10
12UGT85A59
CYP79A125
No
rma
lize
d R
ela
tive
ex
pre
ss
ion
0
1
2
3
4
5
6
CYP706C55
Tip
s
Exp
an
din
g
Exp
an
de
d
Tip
s
Exp
an
din
g
Exp
an
de
d
Tip
s
Exp
an
din
g
Exp
an
de
d
Pru
na
sin
(u
g/m
gd
w)
0
10
20
30
40
50
60
4 months 7 months 10 months 4 months 7 months 10 months
*Significant at P < 0.05 **Significant at P < 0.01
CY
P79A
125
CY
P706C
55
CY
P71B
103
UG
T85A
59
CYP79A125 - 0.552** 0.489** 0.205
CYP706C55 - 0.475* 0.0148
CYP71B103 - -0.0950
UGT85A59 -
TipsExpanding
Expanded
Figure 6. Prunasin accumulation and expression of the biosynthetic genes in 4, 7 and 10 months old E. cladocalyx plants (n = 6-8). A. Prunasin accumulation in apical tips, expanding leaves and expanded leaves. Bars represent mean +/- standard error. Letters denote significance at P < 0.05 by one-way ANOVA analysis. B. Normalized gene expression of CYP79A125, CYP706C55, CYP71B103 and UGT85A59 in apical tips, expanding leaves and expanded leaves. Symbols represent biological replicates (n = 3) C. Spearman correlation analysis of gene expression showing co-regulation of some genes.
B
A C 4 months 7 months 10 months
a
ab
b
c c c c c c
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Parsed CitationsAndersen, M. D., Busk, P. K., Svendsen, I., and Møller, B. L. (2000). "Cytochromes P-450 from cassava (Manihot esculenta Crantz)catalyzing the first steps in the biosynthesis of the cyanogenic glucosides linamarin and lotaustralin: cloning, functional expression inPichia pastoris, and substrate specificity of the isolated recombinant enzymes." J. Biol. Chem., 275, 1966-1975.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Bak, S., Kahn, R. A., Nielsen, H. L., Møller, B. L., and Halkier, B. A. (1998). "Cloning of three A-type cytochromes P450, CYP71E1, CYP98,and CYP99 from Sorghum bicolor (L.) Moench by a PCR approach and identification by expression in Eschericia coli of CYP71E1 as amultifunctional cytochrome P450 in the biosynthesis of the cyanogenic glucoside dhurrin." Plant Mol. Biol, 36, 393-405.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Bassard, J. E., Møller, B. L., and Laursen, T. (2017). "Assembly of Dynamic P450-Mediated Metabolons-Order Versus Chaos." Curr MolBiol Rep, 3(1), 37-51.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Bjarnholt, N., Li, B., D'Alvise, J., and Janfelt, C. (2014). "Mass spectrometry imaging of plant metabolites--principles and possibilities."Nat Prod Rep, 31(6), 818-37.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Bjarnholt, N., Neilson, E. H. J., Crocoll, C., Jørgensen, K., Motawia, M. S., Olsen, C. E., Dixon, D. P., Edwards, R., and Møller, B. L.(2018). "Glutathione transferases catalyze recycling of auto-toxic cyanogenic glucosides in sorghum." Plant J, 94(6), 1109-1125.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Bolger, A. M., Lohse, M., and Usadel, B. (2014). "Trimmomatic: a flexible trimmer for Illumina sequence data." Bioinformatics, 30(15),2114-20.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Boucher, J.-L., Delaforge, M., and Mansuy, D. (1994). "Dehydration of Alkyl- and Arylaldoximes as a New Cytochrome P450-CatalyzedReaction: Mechanism and Stereochemical Characterization." Biochemistry, 33, 7811-7818.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Boughton, B. A., Thinagaran, D., Sarabia, D., Bacic, A., and Roessner, U. (2016). "Mass spectrometry imaging for plant biology: areview." Phytochem Rev, 15, 445-488.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Burchell, B., Nebert, D. W., Nelson, D. R., Bock, K. W., Iyanagi, T., Jansen, P. L. M., Lancet, D., Mulder, G. J., Chowdhury, J. R., Siest, G.,Tephly, T. R., and Mackenzie, P. I. (1991). "The UDP Glucuronosyltransferase Gene Superfamily: Suggested Nomenclature Based onEvolutionary Divergence." DNA Cell Biol, 10(7), 487-494.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Busk, P. K., and Møller, B. L. (2002). "Dhurrin synthesis in sorghum is regulated at the transcriptional level and induced by nitrogenfertilization in older plants." Plant Physiol, 129(3), 1222-31.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Clausen, M., Kannangara, R. M., Olsen, C. E., Blomstedt, C. K., Gleadow, R. M., Jorgensen, K., Bak, S., Motawie, M. S., and Møller, B. L.(2015). "The bifurcation of the cyanogenic glucoside and glucosinolate biosynthetic pathways." Plant J, 84(3), 558-73.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Coppen, J. J. W. (2002). Eucalyptus: the Genus Eucalyptus London: Taylor and Francis.
Darbani, B., Motawia, M. S., Olsen, C. E., Nour-Eldin, H. H., Møller, B. L., and Rook, F. (2016). "The biosynthetic gene cluster for thecyanogenic glucoside dhurrin in Sorghum bicolor contains its co-expressed vacuolar MATE transporter." Sci Rep, 6, 37079.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Del Cueto, J., Ionescu, I. A., Pičmanová, M., Gericke, O., Motawia, M. S., Olsen, C. E., Campoy, J. A., Dicenta, F., Møller, B. L., andSanchez-Perez, R. (2017). "Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy toFlowering." Front Plant Sci, 8, 800.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
DeMaster, E. G., Shirota, F. N., and Nagasawa, H. T. (1992). "A Beckmann-type dehydration of n-butyraldoxime catalyzed by cytochrome www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
P-450." J. Org. Chem, 57, 5074-5075.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Dobin, A., Davis, C. A., Schlesinger, F., Drenkow, J., Zaleski, C., Jha, S., Batut, P., Chaisson, M., and Gingeras, T. R. (2013). "STAR:ultrafast universal RNA-seq aligner." Bioinformatics, 29(1), 15-21.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Eschler, B. M., Pass, D. M., Willis, R., and Foley, W. J. (2000). "Distribution of foliar formylated phloroglucinol derivatives amongstEucalyptus species." Biochem. Syst. Ecol., 28(9), 813-824.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Finnemore, H., and Cox, C. B. (1928). "Cyanogenetic glucosides in Australian Plants." J. Proc. Roy. Soc. NSW, 62, 369-378.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Finnemore, H., Reichard, S. K., and Large, D. K. (1935). "Cyanogenetic glucosides in Australian plants: Eucalyptus cladocalyx." J. Proc.Roy. Soc. NSW, 69, 209-214.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Forslund, K., Morant, M., Jørgensen, B., Olsen, C. E., Asamizu, E., Sato, S., Tabata, S., and Bak, S. (2004). "Biosynthesis of the nitrileglucosides rhodiocyanoside A and D and the cyanogenic glucosides lotaustralin and linamarin in Lotus japonicus." Plant Physiol,135(1), 71-84.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Franks, T. K., Yadollahi, A., Wirthensohn, M. G., Huerin, J. R., Kaiser, B. N., Sedgley, M., and Ford, C. M. (2008). "A seed coatcyanohydrin glucosyltransferase is associated with bitterness in almond (Prunus dulcis) kernels." Funct. Plant Biol., 35(3), 236-246.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Franzmayr, B. K., Rasmussen, S., Fraser, K. M., and Jameson, P. E. (2012). "Expression and functional characterization of a whiteclover isoflavone synthase in tobacco." Ann Bot, 110(6), 1291-301.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., Foley, W. J., and Woodrow, I. E. (1998). "Enhanced CO2 alters the relationship between photosynthesis and defence incyanogenic Eucalyptus cladocalyx F. Muell." Plant Cell Environ, 21, 12-22.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., Haburjak, J., Dunn, J. E., Conn, M. E., and Conn, E. E. (2008). "Frequency and distribution of cyanogenic glycosides inEucalyptus L'Herit." Phytochemistry, 69(9), 1870-4.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., and Møller, B. L. (2014). "Cyanogenic glycosides: synthesis, physiology, and phenotypic plasticity." Annu Rev PlantBiol, 65, 155-85.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., and Woodrow, I. E. (2000a). "Polymorphism in cyanogenic glycoside content and cyanogenic β-glucosidase activity innatural populations of Eucalyptus cladocalyx." Aust. J. Plant Physiol., 27, 693-699.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., and Woodrow, I. E. (2000b). "Temporal and spatial variation in cyanogenic glycosides in Eucalyptus cladocalyx." TreePhysiol, 20(9), 591-598.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Gleadow, R. M., and Woodrow, I. E. (2002). "Constraints on effectiveness of cyanogenic glycoside in herbivore defense." J. Chem.Ecol., 28, 1301-1313.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Goodger, J. Q., Choo, T. Y., and Woodrow, I. E. (2007). "Ontogenetic and temporal trajectories of chemical defence in a cyanogeniceucalypt." Oecologia, 153(4), 799-808.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Goodger, J. Q. D., Ades, P. K., and Woodrow, I. E. (2004). "Cyanogenesis in Eucalyptus polyanthemos seedlings: heritability, ontogeny www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
and effect of soil nitrogen." Tree Physiology, 24, 681-688.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Goodger, J. Q. D., Gleadow, R. M., and Woodrow, I. E. (2006). "Growth cost and ontogenetic expression patterns of defence incyanogenic Eucalyptus spp." Trees, 20(6), 757-765.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Goodstein, D. M., Shu, S., Howson, R., Neupane, R., Hayes, R. D., Fazo, J., Mitros, T., Dirks, W., Hellsten, U., Putnam, N., and Rokhsar,D. S. (2012). "Phytozome: a comparative platform for green plant genomics." Nucleic Acids Res, 40(Database issue), D1178-86.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Hart-Davis, J., Battioni, P., Boucher, J.-L., and Mansuy, D. (1998). "New catalytic properties of iron porphyrins: model systems forcytochrome P450-catalyzed dehydration of aldoximes." J. Am. Chem. Soc., 120, 12524-12530.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Hearne, P. Q., Knorr, D. A., Hillman, B., and Morris, T. J. (1990). "The complete genome structure and synthesis of infectious RNA fromclones of tomato bushy stunt virus." Virology, 177(1), 141-151.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Hellemans, J., Mortier, G., de Peape, A., Speleman, F., and Vandesompele, J. (2007). "qBase relative quantification framework andsothware for management and automated analysis of real-time quantitative PCR data." Genome Biology, 8, R19.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Haas, B. J., Papanicolaou, A., Yassour, M., Grabherr, M., Blood, P. D., Bowden, J., Couger, M. B., Eccles, D., Li, B., Lieber, M.,MacManes, M. D., Ott, M., Orvis, J., Pochet, N., Strozzi, F., Weeks, N., Westerman, R., William, T., Dewey, C. N., Henschel, R., LeDuc, R.D., Friedman, N., and Regev, A. (2013). "De novo transcript sequence reconstruction from RNA-seq using the Trinity platform forreference generation and analysis." Nat Protoc, 8(8), 1494-512.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Irmisch, S., Clavijo McCormick, A., Gunther, J., Schmidt, A., Boeckler, G. A., Gershenzon, J., Unsicker, S. B., and Köllner, T. G. (2014)."Herbivore-induced poplar cytochrome P450 enzymes of the CYP71 family convert aldoximes to nitriles which repel a generalistcaterpillar." Plant J, 80(6), 1095-107.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Irmisch, S., McCormick, A. C., Boeckler, G. A., Schmidt, A., Reichelt, M., Schneider, B., Block, K., Schnitzler, J. P., Gershenzon, J.,Unsicker, S. B., and Köllner, T. G. (2013). "Two herbivore-induced cytochrome P450 enzymes CYP79D6 and CYP79D7 catalyze theformation of volatile aldoximes involved in poplar defense." Plant Cell, 25(11), 4737-54.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Jenrich, R., Trompetter, I., Bak, S., Olsen, C. E., Møller, B. L., and Piotrowski, M. (2007). "Evolution of heteromeric nitrilase complexesin Poaceae with new functions in nitrile metabolism." Proc Natl Acad Sci U S A, 104(47), 18848-53.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Jensen, N. B., Zagrobelny, M., Hjerno, K., Olsen, C. E., Houghton-Larsen, J., Borch, J., Møller, B. L., and Bak, S. (2011). "Convergentevolution in biosynthesis of cyanogenic defence compounds in plants and insects." Nat Commun, 2, 273.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Jones, P., Binns, D., Chang, H. Y., Fraser, M., Li, W., McAnulla, C., McWilliam, H., Maslen, J., Mitchell, A., Nuka, G., Pesseat, S., Quinn, A.F., Sangrador-Vegas, A., Scheremetjew, M., Yong, S. Y., Lopez, R., and Hunter, S. (2014). "InterProScan 5: genome-scale proteinfunction classification." Bioinformatics, 30(9), 1236-40.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Jones, P. R., Møller, B. L., and Høj, P. B. (1999). "The UDP-glucose:p-Hydroxymandelonitrile-O-Glucosyltransferase That Catalyzes theLast Step in Synthesis of the Cyanogenic Glucoside Dhurrin in Sorghum bicolor." Journal of Biological Chemistry, 274(50), 35483-35491.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Jørgensen, K., Bak, S., Busk, P. K., Sørensen, C., Olsen, C. E., Puonti-Kaerlas, J., and Møller, B. L. (2005). "Cassava plants with adepleted cyanogenic glucoside content in leaves and tubers. Distribution of cyanogenic glucosides, their site of synthesis andtransport, and blockage of the biosynthesis by RNA interference technology." Plant Physiol, 139(1), 363-74.
Pubmed: Author and Title www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
Google Scholar: Author Only Title Only Author and Title
Jørgensen, K., Morant, A. V., Morant, M., Jensen, N. B., Olsen, C. E., Kannangara, R., Motawia, M. S., Møller, B. L., and Bak, S. (2011)."Biosynthesis of the cyanogenic glucosides linamarin and lotaustralin in cassava: isolation, biochemical characterization, andexpression pattern of CYP71E7, the oxime-metabolizing cytochrome P450 enzyme." Plant Physiol, 155(1), 282-92.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Kahn, R. A., Bak, S., Svendsen, I., Halkier, B. A., and Møller, B. L. (1997). "Isolation and Reconstitution of Cytochrome P450ox and inVitro Reconstitution of the Entire Biosynthetic Pathway of the Cyanogenic Glucoside Dhurrin from Sorghum." Plant Physiol, 115, 1661-1670.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Kahn, R. A., Fahrendorf, T., Halkier, B. A., and Møller, B. L. (1999). "Substrate specificity of the cytochrome P450 enzymes CYP79A1 andCYP71E1 involved in the biosynthesis of the cyanogenic glucoside dhurrin in Sorghum bicolor (L.) Moench." Arch. Biochem. Biophys.,363, 9-18.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Kannangara, R., Motawia, M. S., Hansen, N. K., Paquette, S. M., Olsen, C. E., Møller, B. L., and Jørgensen, K. (2011). "Characterizationand expression profile of two UDP-glucosyltransferases, UGT85K4 and UGT85K5, catalyzing the last step in cyanogenic glucosidebiosynthesis in cassava." Plant J, 68(2), 287-301.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Koch, B. M., Sibbesen, O., Halkier, B. A., Svendsen, I., and Møller, B. L. (1995). "The primary sequence of cytochrome P450tyr, themultifunctional N-hydroxylase catalyzing the conversion of L-tyrosine to p-hydroxyphenylacetaldehyde oxime in the biosynthesis of thecyanogenic glucoside dhurrin in Sorghum bicolor (L.) Moench." Arch. Biochem. Biophys., 323, 177-186.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Kulheim, C., Padovan, A., Hefer, C., Krause, S. T., Kollner, T. G., Myburg, A. A., Degenhardt, J., and Foley, W. J. (2015). "The Eucalyptusterpene synthase gene family." BMC Genomics, 16, 450.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Kumar, S., Stecher, G., and Tamura, K. (2016). "MEGA7: Molecular Evolutionary Genetics Analysis Version 7.0 for Bigger Datasets." MolBiol Evol, 33(7), 1870-4.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Lai, D., Pičmanová, M., Abou Hachem, M., Motawia, M. S., Olsen, C. E., Møller, B. L., Rook, F., and Takos, A. M. (2015). "Lotus japonicusflowers are defended by a cyanogenic beta-glucosidase with highly restricted expression to essential reproductive organs." Plant MolBiol, 89(1-2), 21-34.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Lakatos, L., Szittya, G., DSilhavy, D., and Burgyán, J. (2004). "Melcular mechanism of RNA silencing suppression mediated by p19protein of tombusviruses." EMBO J., 23(4), 876-884.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Laursen, T., Borch, J., Knudsen, C., Bavishi, K., Torta, F., Martens, H. J., Silvestro, D., Hatzakis, N., Wenk, M. R., Dafforn, T. R., Olsen,C. E., Motawia, M. S., Hamberger, B., Møller, B. L., and Bassard, J.-E. (2016). "Characterization of a dynamic metabolon producing thedefense compund dhurrin in sorghum." Science, 354(6314), 890-893.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Lazo, G. R., Stein, P. A., and Ludwig, R. A. (1991). "A DNA treansformation-competent Arabidopsis library in Agrobacterium."Biotechnology (N Y), 9(10), 963-967.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Liu, X., Cheng, J., Zhang, G., Ding, W., Duan, L., Yang, J., Kui, L., Cheng, X., Ruan, J., Fan, W., Chen, J., Long, G., Zhao, Y., Cai, J., Wang,W., Ma, Y., Dong, Y., Yang, S., and Jiang, H. (2018). "Engineering yeast for the production of breviscapine by genomic analysis andsynthetic biology approaches." Nat Commun, 9(1), 448.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
London-Shafir, I., Shafir, S., and Eisikowitch, D. (2003). "Amygdalin in almond nectar and pollen – facts and possible roles." PlantSystematics and Evolution, 238(1-4), 87-95.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
Luo, J., Nishiyama, Y., Fuell, C., Taguchi, G., Elliott, K., Hill, L., Tanaka, Y., Kitayama, M., Yamazaki, M., Bailey, P., Parr, A., Michael, A. J.,Saito, K., and Martin, C. (2007). "Convergent evolution in the BAHD family of acyl transferases: identification and characterization ofanthocyanin acyl transferases from Arabidopsis thaliana." Plant J, 50(4), 678-95.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Luo, P., Wang, Y.-H., Wang, G.-D., Essenberg, and Chen, X.-Y. (2001). "Molecular cloning and functional identification of (+)-δ-8-hydroxylase, a cytochrome P450 mono-oxygenase (CYP706B1) of cotton sesquiterpene biosynthesis." The Plant Journal, 28(1), 95-104.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Mackenzie, P. I., Bock, K. W., Burchell, B., Guillemette, C., Ikushiro, S.-i., Iyanagi, T., Miners, J. O., Owens, I. S., and Nebert, D. W.(2005). "Nomenclature update for the mammalian UDP glycosyltransferase (UGT) gene superfamily." Pharmacogenet Genomic, 15, 677-685.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Marsh, K. J., Kulheim, C., Blomberg, S. P., Thornhill, A. H., Miller, J. T., Wallis, I. R., Nicolle, D., Salminen, J. P., and Foley, W. J. (2017)."Genus-wide variation in foliar polyphenolics in eucalypts." Phytochemistry, 144, 197-207.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
McCormick, A. C., Irmisch, S., Reinecke, A., Boeckler, G. A., Veit, D., Reichelt, M., Hansson, B. S., Gershenzon, J., Kollner, T. G., andUnsicker, S. B. (2014). "Herbivore-induced volatile emission in black poplar: regulation and role in attracting herbivore enemies." PlantCell Environ, 37(8), 1909-23.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Myburg, A. A., Grattapaglia, D., Tuskan, G. A., Hellsten, U., Hayes, R. D., Grimwood, J., Jenkins, J., Lindquist, E., Tice, H., Bauer, D.,Goodstein, D. M., Dubchak, I., Poliakov, A., Mizrachi, E., Kullan, A. R., Hussey, S. G., Pinard, D., van der Merwe, K., Singh, P., vanJaarsveld, I., Silva-Junior, O. B., Togawa, R. C., Pappas, M. R., Faria, D. A., Sansaloni, C. P., Petroli, C. D., Yang, X., Ranjan, P.,Tschaplinski, T. J., Ye, C. Y., Li, T., Sterck, L., Vanneste, K., Murat, F., Soler, M., Clemente, H. S., Saidi, N., Cassan-Wang, H., Dunand,C., Hefer, C. A., Bornberg-Bauer, E., Kersting, A. R., Vining, K., Amarasinghe, V., Ranik, M., Naithani, S., Elser, J., Boyd, A. E., Liston, A.,Spatafora, J. W., Dharmwardhana, P., Raja, R., Sullivan, C., Romanel, E., Alves-Ferreira, M., Kulheim, C., Foley, W., Carocha, V., Paiva, J.,Kudrna, D., Brommonschenkel, S. H., Pasquali, G., Byrne, M., Rigault, P., Tibbits, J., Spokevicius, A., Jones, R. C., Steane, D. A.,Vaillancourt, R. E., Potts, B. M., Joubert, F., Barry, K., Pappas, G. J., Strauss, S. H., Jaiswal, P., Grima-Pettenati, J., Salse, J., Van dePeer, Y., Rokhsar, D. S., and Schmutz, J. (2014). "The genome of Eucalyptus grandis." Nature, 510(7505), 356-62.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Møller, B. L. (2010). "Functional diversifications of cyanogenic glucosides." Curr Opin Plant Biol, 13(3), 338-47.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Møller, B. L., Olsen, C. E., and Motawia, M. S. (2016). "General and Stereocontrolled Approach to the Chemical Synthesis of NaturallyOccurring Cyanogenic Glucosides." J Nat Prod, 79(4), 1198-202.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Nafisi, M., Goregaoker, S., Botanga, C. J., Glawischnig, E., Olsen, C. E., Halkier, B. A., and Glazebrook, J. (2007). "Arabidopsiscytochrome P450 monooxygenase 71A13 catalyzes the conversion of indole-3-acetaldoxime in camalexin synthesis." Plant Cell, 19(6),2039-52.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Neilson, E. H. (2012). Characterisation of Cyanogenic Glucoside Synthesis in Eucalyptus, PhD thesis, University of Melbourne.
Neilson, E. H., Goodger, J. Q., Motawia, M. S., Bjarnholt, N., Frisch, T., Olsen, C. E., Møller, B. L., and Woodrow, I. E. (2011)."Phenylalanine derived cyanogenic diglucosides from Eucalyptus camphora and their abundances in relation to ontogeny and tissuetype." Phytochemistry, 72(18), 2325-34.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Nelson, D. N. (2009). "The Cytochrome P450 Homepage." Hum Genomics, 4(1), 59-65.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Nielsen, L. J., Stuart, P., Pičmanová, M., Rasmussen, S., Olsen, C. E., Harholt, J., Møller, B. L., and Bjarnholt, N. (2016). "Dhurrinmetabolism in the developing grain of Sorghum bicolor (L.) Moench investigated by metabolite profiling and novel clustering analysesof time-resolved transcriptomic data." BMC Genomics, 17(1), 1021.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Noge, K., Abe, M., and Tamogami, S. (2011). "Phenylacetonitrile from the giant knotweed, Fallopia sachalinensis, infested by the www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.
Japanese beetle, Popillia japonica, is induced by exogenous methyl jasmonate." Molecules, 16(8), 6481-8.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Padovan, A., Keszei, A., Külheim, C., and Foley, W. J. (2014). "The evolution of foliar terpene diversity in Myrtaceae." Phytochem Rev,13(3), 695-716.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Paupiere, M. J., van Heusden, A. W., and Bovy, A. G. (2014). "The metabolic basis of pollen thermo-tolerance: perspectives forbreeding." Metabolites, 4(4), 889-920.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Pičmanová, M., Neilson, E. H., Motawia, M. S., Olsen, C. E., Agerbirk, N., Gray, C. J., Flitsch, S., Meier, S., Silvestro, D., Jørgensen, K.,Sanchez-Perez, R., Møller, B. L., and Bjarnholt, N. (2015). "A recycling pathway for cyanogenic glycosides evidenced by thecomparative metabolic profiling in three cyanogenic plant species." Biochem J, 469(3), 375-89.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Rhoades, D. F. (1979). "Evolution of plant chemical defense against herbivores.", in G. A. Rosenthal and D. H. Janzen, (eds.),Herbivores: their interaction with secondary plant metabolites. New York: Academic Press, pp. 3-54.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Roberts, A., and Pachter, L. (2013). "Streaming fragment assignment for real-time analysis of sequencing experiments." Nat Methods,10(1), 71-3.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Schmidt, F. B., Cho, S. K., Olsen, C. E., Yang, S. W., Møller, B. L., and Jørgensen, K. (2018a). "Diurnal regulation of cyanogenicglucoside biosynthesis and endogenous turnover in cassava." Plant Direct, 2(2), e00038.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Schmidt, F. B., Heskes, A. M., Thinagaran, D., Møller, B. L., Jørgensen, K., and Boughton, B. A. (2018b). "Mass Spectrometry BasedImaging of Labile Glucosides in Plants." Front Plant Sci, 9, 892.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Selmar, D. (1993). "Transport of cyanogenic glucosides: linustatin uptake by Hevea cotyledons." Planta, 191(2), 191-199.Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Selmar, D., Irandoost, Z., and Wray, V. (1996). "Dhurrin-6'-glucoside, a cyanogenic diglucoside from Sorghum bicolor." Phytochemistry,43(3), 569-572.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Selmar, D., Lieberel, R., and Biehl, B. (1988). "Mobilization and Utilization of Cyanogenic Glucosides. The Linustatin Pathway." PlantPhysiol, 86, 711-716.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Spokevicius, A. V., Tibbits, J., Rigault, P., Nolin, M. A., Muller, C., and Merchant, A. (2017). "Medium term water deficit elicits distincttranscriptome responses in Eucalyptus species of contrasting environmental origin." BMC Genomics, 18(1), 284.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Sørensen, M., Neilson, E. H. J., and Møller, B. L. (2018). "Oximes: Unrecognized Chameleons in General and Specialized PlantMetabolism." Mol Plant, 11(1), 95-117.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Takos, A. M., Knudsen, C., Lai, D., Kannangara, R., Mikkelsen, L., Motawia, M. S., Olsen, C. E., Sato, S., Tabata, S., Jørgensen, K.,Møller, B. L., and Rook, F. (2011). "Genomic clustering of cyanogenic glucoside biosynthetic genes aids their identification in Lotusjaponicus and suggests the repeated evolution of this chemical defence pathway." Plant J, 68(2), 273-86.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Thodberg, S., Cueto, J. D., Mazzeo, R., Pavan, S., Lotti, C., Dicenta, F., Neilson, E. H., Møller, B. L., and Sánchez-Pérez, R. (2018). "Thebedrock of almond bitterness: the amygdalin pathway in almond (Prunus dulcis)." Plant Physiology, accepted manuscript.
Tian, L., and Dixon, R. A. (2006). "Engineering isoflavone metabolism with an artificial bifunctional enzyme." Planta, 224(3), 496-507.Pubmed: Author and Title www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from
Copyright © 2018 American Society of Plant Biologists. All rights reserved.
Google Scholar: Author Only Title Only Author and Title
Ting, H. M., Wang, B., Ryden, A. M., Woittiez, L., van Herpen, T., Verstappen, F. W., Ruyter-Spira, C., Beekwilder, J., Bouwmeester, H. J.,and van der Krol, A. (2013). "The metabolite chemotype of Nicotiana benthamiana transiently expressing artemisinin biosyntheticpathway genes is a function of CYP71AV1 type and relative gene dosage." New Phytol, 199(2), 352-66.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Vandesompele, J., de Preter, K., Pattyn, F., Poppe, B., van Roy, N., de Paepe, A., and Speleman, F. (2002). "Accurate normalization ofreal-time quantitative RT-PCR data by geometric averaging of multiple internal control genes." Genome Biology, 3(7), research0034.1–research0034.11.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Vetter, J. (2017). "Plant Cyanogenic Glycosides", in P. Gopalakrishnakone, C. R. Carlini, and R. Ligabue-Braun, (eds.), Plant Toxins.Springer, pp. 287-317.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Voinnet, O., Pinto, Y. M., and Baulcombe, D. C. (1999). "Suppression of gene silencing: A general strategy used by diverse DNA andRNA viruses of plants." Proc Natl Acad Sci U S A, 96(24), 14147-14152.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Yamaguchi, T., Kuwahara, Y., and Asano, Y. (2017). "A novel cytochrome P450, CYP3201B1, is involved in (R)-mandelonitrilebiosynthesis in a cyanogenic millipede." FEBS Open Bio, 7(3), 335-347.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Yamaguchi, T., Noge, K., and Asano, Y. (2016). "Cytochrome P450 CYP71AT96 catalyses the final step of herbivore-inducedphenylacetonitrile biosynthesis in the giant knotweed, Fallopia sachalinensis." Plant Mol Biol, 91(3), 229-39.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
Yamaguchi, T., Yamamoto, K., and Asano, Y. (2014). "Identification and characterization of CYP79D16 and CYP71AN24 catalyzing thefirst and second steps in L‑phenylalanine‑derived cyanogenic glycoside biosynthesis in the Japanese apricot, Prunus mume Sieb. etZucc." Plant Mol Biol, 86, 215-223.
Pubmed: Author and TitleGoogle Scholar: Author Only Title Only Author and Title
www.plantphysiol.orgon July 9, 2020 - Published by Downloaded from Copyright © 2018 American Society of Plant Biologists. All rights reserved.