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Department of Botany, Royal Holloway College (University of London), Egham Hill, Egham, Surrey, England
Carotenoids of Lilies and of Red Pepper: Biogenesis of Capsanthin and Capsorubin
L. R. G. V ALADON and ROSEMARY S. MUMMERY
With 2 figures
Received November 5, 1976 . Accepted December 1, 1976
Summary
Carotenoids of petals of the following lilies: Lilium leichtinii var. Maximowiczii, L. Davidii var. Willmottiae and of their hybrid L. Maxwill were investigated as they all contained capsanthin and capsorubin. The hybrid possessed not only the parent carotenoids but also fl-carotene monoepoxide, cryptocapsin and lutein not found in the parents. Carotenoids not present in parents but in hybrids have already been observed in citrus hybrids. Petals of L. amabile, a redder flower, had very much the same carotenoids as the others studied. Capsanthin and capsorubin were also found together when Capsicum annuum var. grossum (pepper) fruits matured but not at the green photosynthetic stage. Our results both with lilies and pepper fruits correlated well with the biosynthetic pathway proposed for capsanthin and capsorubin formation.
No new carotenoids were observed in other floral parts of lilies investigated. However, antheraxanthin which had been suggested as a carotenoid specifically associated with reproduction in higher plants was found as the main carotenoid of the anthers investigated.
Key words: carotenoids, lilies, Lilium, capsanthin, capsorubin, peppers, Capsicum annuum.
Introduction
Capsanthin (IX) and capsorubin (XIV) are typical carotenoids of red pepper, Capsicum annuum (CHOLNOKY, GYORGYFY, NAGY and PANCZEL, 1956; CURL, 1962; DAVIES, MATTHEWS and KIRK, 1970; SIMPSON, RAHMAN, BUCKLE and LEE, 1974). These compounds with one and two acylcyclopentanol rings respectively are rare in nature and besides their appearance in red peppers have only been identified in the brown-red tunicate Botryllus schlosseri presumably feeding on pimento pepper waste (LONNBERG and HELLSTROM, 1931) and in anthers of various lilies (KARRER and OSWALD, 1935). Also in flowers of Aesculus rubicunda (NEAMTU and BODEA, 1973). KARRER, EUGSTER and FAUST (1950) working on pollens and anthers of various plants concluded that cis-antheraxanthin seemed to be characteristic of lily anthers although this carotenoid was usually accompanied by capsanthin. The presence of the latter carotenoid in these anthers was rather unexpected (GOODWIN,
z. Pjlanzenphysiol. Bd. 82. S. 407-41Q. 1977.
408 L. R. G. VALADON and ROSEMARY S. MUMMERY
1952) yet it may be on the direct biosynthetic route from zeaxanthin VIa the 5,6-epoxy compound antheraxanthin (WEEDON, 1971).
]UNGALWALA and CAMA (1962) examined various parts of the flowers of Delonix regia and found that the highest concentrations of total carotenoids were in anthers and that certain carotenoids were only present in a particular floral part. The present study was undertaken to assess the possibility that the same situation existed in lilies and that since diverse floral parts may have different carotenoids, then new carotenoids might be found in certain parts which could be intermediates in the formation of capsanthin. This would give invaluable information as to the biogenesis and role of carotenoids in lilies.
Very little work has been carried out systematically on the floral carotenoids of parents and hybrids. YOKOYAMA and WHITE (1966) studied citrus hybrids and found the unique methyl ketones sintaxanthin, citranaxanthin and reticulaxanthin in hybrids of the oval kumquat with the Rusk citrange whereas neither parent produced more than traces, if any, of these pigments. It was possible for us to obtain two parents (Lilium Davidii var. Willmottiae and L. leichtinii var. Maximowiczii) which gave rise to the hybrid L. Maxwill. The carotenoid composition of flowers of these varieties was studied to determine whether new and/or different carotenoids would be identified in the hybrid. Capsanthin and capsorubin were identified in all petals
~ __ 111 ~---~LO-.~----~ _o2Jl I ----~-~o- - I - /". U o · - ~
(I) (II) (:II) OH
~l~_~_~_~._~ HO (IV) (V) ~(VI) OH
1 OH OH
~---~~---~IQ~-- ~- 0
:: 0" ":~:: ~ ___ "':'~:O~ '''' ~ Y'V '~-Vo· - ~<~~I~O ~ *~", "HO (X) flO <:: (X!;)
(AI) (; ~ 1 Of!
~ __ -"'- ~ J.-r IO~,> __ ~ ~o . I~~O IT 0
HO (Xi;:) Y (m) OH
Fig. 1: Biosynthesis of capsanthin and related compounds modified from DAVIES, MATTHEWS and KIRK (1970). 13-carotene (I); ~-carotene-5,6-epoxide (II); ~-carotene-5,6 : 5',6' -diepoxidc (III); cryptoxanthin (IV); cryptoxanthin-5,6-epoxide (V); cryptocapsin (VI); zeaxanthin (VII); antheraxanthin (VIII); capsanthin (IX); violaxanthin (X); neoxanthin (XI); capsanthin-5,6-epoxide (XII); capsochrome (XIII); capsorubin (XIV).
Z. Pflanzenphysiol. Bd. 82. S. 407-416.1977.
Carotenoids of lilies and of red pepper 409
under investigation and more information was obtained in terms of biogenesis of these carotenoids.
DAVIES, MATTHEWS and KIRK (1970) having investigated the carotenoids of the white-, yellow-, orange- and red-fruiting varieties of the ornamental pepper were able to agree with some of the biosynthetic steps leading to cap so rubin formation as proposed by CHOLNOKY, GYORGYFY, NAGY and PANCZEL (1956) (Fig. 1). When attempting to isolate pure capsanthin and capsorubin from red peppers we observed varying amounts of these pigments depending on the age of the fruits. It is well known that as fruits mature different carotenoids in various amounts appear which help one to understand carotenoid biosynthesis further (VAL AD ON and MUMMERY, 1969; 1972 a). Carotenoids of peppers of increasing maturity were investigated in an attempt to clarify certain biosynthetic steps leading to capsorubin formation.
Material and Methods
Lily bulbs purchased from P. de Jager & Sons Ltd., Marden, Kent were grown in the Botany Department greenhouses and flowers became available between June and August, 1976. The following lilies were obtained: Lilium Davidii var. Willmottiae, L. leichtinii var. Maximowiczii and their hybrid L. Maxwill. L. Davidii var. Willmottiae bears up to thirty flowers, vivid rich orange-red of recurving form covered with small dark-brown spots; L. leichtinii var. Maximowiczii bears up to ten reflexing vivid orange-red flowers spotted with purple-brown. L. Maxwill bears a very long pyramidal inflorescence of about thirty recurving brilliant orange-red flowers, spotted brown. Another lily L. amabile was also used for comparison. It had reflexed flowers of rich, pomegranate red, spotted black.
Peppers Capsicum annuum var. grossum, Sendt at different stages of maturity were bought from the local market. CPTA 2-( 4-chlorophenylthio )-ethyldiethyl-ammonium chloride treated fruit was produced as follows: green fruits were dipped in CPT A solution (5,000 p.p.m.) for 1 minute and ripened for two weeks at 20°C. The resulting fruits were pinkish-red when compared to the bright red colour of normal red peppers.
The various parts were extracted several times with methanol in a Waring Blendor and then with acetone until no more colour was extracted. Partition with diethyl ether was performed and all the colour was transferred to the epiphasic layer, which was concentrated under reduced pressure at about 35°C. Procedures for the saponification of the extracts, the removal of some sterols, the phase partition of carotenoids between n-hexane and aqueous 90 % methanol, and the separation and identification of carotenoids by column and thin-layer chromatography were as described previously (VALADON and MUMMERY, 1968, 1975). Circular chromatography on silica gel paper Whatman SG 81 was as described by VALADON and MUMMERY, 1972 b.
Carotenoids having epoxy-groups were characterised by the modified conc. HCI-ether test of JUNGALWALA and CAMA (1962).
The structural identity of individual carotenoids was established by comparison with authentic samples using various chromatographic methods as already described, and visible and IR spectroscopy. Keto-carotenoids were further identified by reduction with LiAIH4 when the corresponding mono- or di-ols were obtained (CURL, 1962).
The concentrations of individual carotenoids were determined by measuring Emax and
comparing it with known E 11 % at Amax for pure pigments (VALADON and MUMMERY, cm
1975). For those pigments whose Ell % were not known, Amax was assumed to be 2500 cm
(GOODWIN, 1954). All results were calculated on a per gram dry-weight basis.
z. Pjlanzenphysiol. Bd. 82. s. 407-416.1977.
410 L. R. G. VALADON and ROSEMARY S. MUMMERY
Results and Discussion
Seventeen different carotenoids were indentified in the various floral parts of lilies (Table 1). Of the parts studied, the highest concentration of total carotenoids was in the anthers, followed by petals of L. Davidii var. Willmottiae. The carotenoid composition of the petals was similar to that of Capsium annuum fruits (DAVIES, MATTHEWS and KIRK, 1970) 10 that they contained fJ-carotene, {J-carotene-S,6-epoxide, cryptoxanthin, cryptocapsin, lutein, zeaxanthin, antheraxanthin, violaxanthin, capsanthin, capsanthin-S,6-epoxide, capsorubin and neoxanthin; lacked hydroxy-a-carotene but possessed in addition phytofluene, {J-carotene-S,6 : S',6'-diepoxide, cryptoxanthin-S,6-epoxide and capsochrome. It is to be noted that cis- and trans- forms of a number of carotenoids were identified sometimes with the cis-form in larger amounts than the trans-form. The central double-bond of naturally occurring phytoene - the C40 precursor of carotenoids -in higher plants in cis (DAVIS, JACKMAN, SIDDONS and WEEDON, 1961) although natural carotenoids are usually in the trans-form. MAUDINAS, HERBER and VILLOUTREIX (1974) working with a number of micro-organisms advanced an hypothesis for the biological occurrence of cis- and trans-isomers of phytoene. The trans-form was strongly stimulated by light and the two forms might well be in equilibrium. Accordingly if the same applies to higher plants then the situation may be represented as in Fig. 2.
ci s-Phytoene -- trans-~ytoene -I ~
{- 1 i'
cis-Cryptoxanthin -- trans-Cryptoxanthin -~ ~ -~
cis-Zeaxanthin -- trans-Zeaxanthin -f ---r -,t. cis-Antheraxanthin ---- trans-Antheraxanthin -,,- ---po -~
cis-Violaxanthin -- trans-Violaxanthin ~
+ t cis-Neoxanthin - trans-Neoxanthin
---r
Fig. 2: Possible pathway of cis- and trans-isomers of carotenoids in higher plants. - - ~ indicates several steps.
This may be likened to the pathway suggested by RAYMUNDO and SIMPSON (1972) working with the tangerine tomato.
Petals of L. Maxwill were examined at two stages: (1) three days after anthesis referred to as early stage and (2) two weeks later (later stage). It can be seen from Table 1 that the later stage had more total and more individual carotenoids than the early stage. Because of the increase in the number of carotenoids there was a great
z. Pjlanzenphysiol. Bd. 82. s. 407-416. 1977.
Tab
le 1
: C
aro
ten
oid
s in
div
erse
flo
ral
par
ts o
f va
riou
s li
lies
.
Pet
als
of
Ant
hers
of
Sty
les
of
Car
ote
no
id
L. a
mab
ile
L.
Max
wil
l L
. M
axw
ill
L.
Dav
idii
var
. L
. le
icht
inii
L.
Max
wil
l L.
Max
wil
l (e
arly
sta
ge)
(lat
er s
tage
) W
illr
nott
iae
var
. M
axim
ovic
zii
H
H
P2
Pi
Ph
yto
flu
ene
0.3
0.2
trac
e ~-Carotene
0.9
1.0
1.0
0.6
0.5
3.7
~-Carotene-5
,6-e
poxi
de
0.1
~-Carotene-5,6 :
5',6
' -di
epox
ide
0.8
0.1
0.4
7.7
tran
s-C
rypt
oxan
thin
11
.7
0.3
8.0
0.2
4.0
8.9
cis-
Cry
pto
xan
thin
2.
9 1.
0 C
ryp
tox
anth
in-5
,6-e
po
xid
e 1.
6 0.
5 1.
5 16
.8
tran
s-C
rypt
ocap
sin
1.3
1.4
13.3
0.
8 11
.4
cis-
Cry
pto
cap
sin
2.
5 1.
4 tr
ans-
Vio
lax
anth
in
7.0
1.2
4.1
20.2
5.
7 3.
0 ()
Il.l
cis-
Vio
lax
anth
in
0.2
0.1
1.2
... g N
(I
>
::l
"l:!
tran
s-A
nth
erax
anth
in
11.3
0.
6 18
.1
16.0
15
.6
33.8
11
.3
0 .....
.. ci
s-A
nth
erax
anth
in
0.:
$:\
22.5
13
.8
4.3
8.5
6.0
'" ;:
L
ute
in
0.7
0
'" .....
. '" ;:
tran
s-Z
eaxa
nthi
n 0.
8 1.
5 5.
2 3.
9 15
.1
-":
> -
~
cis-
Zea
xan
thin
3.
4 0.
5 0.
7 n;
. ~
'" N
eox
anth
in
0.1
0.6
2.9
Il.l
o· ::l
:-
Cap
soch
rorn
e 1.
4 3.
9 p.
. ~
Cap
san
thin
-5,6
-ep
ox
ide
2.0
2.6
2.7
11.4
0
?-.....
. 0
0
tran
s-C
apsa
nthi
n 25
.7
46.6
19
.0
38.6
38
.7
21.6
45
.4
... (I>
N
p..
'" C
arb
on
yl
(458
nrn
) 0,
8 0.
3 '"
0 tr
ans-
Cap
soru
bin
13.5
31
.8
11.6
7.
4 7.
6 1.
4 13
.1
(I>
"'" '"
0 C
>
cis-
Cap
soru
bin
6.2
'"0
I'
(I>
... "'" .....
. ?'
To
tal
Car
ote
no
ids
(rng
/g)
6.06
3.
68
5.47
10
.48
4.82
16
.31
6.41
.....
. \0
""""
" (v
alue
s gi
ven
are
perc
enta
ge o
f to
tal
caro
teno
ids)
....
~
....
412 L. R. G. VALADON and ROSEMARY S. MUMMERY
reduction in capsanthin and capsorubin from approximately 47010 to 19 % and from 32 Ofo to 12 % respectively, with capsanthin no longer the main pigment, but antheraxanthin (32010). It is well known that as flowers and fruits mature, different carotenoids appear. This is well exemplified in the present study and hence flowers were cut seventeen days after anthesis to obtain fairly comparable results.
Carotenoids of L. amabile were very similar to those found in the other lilies and especially with later stage L. Maxwill even though flowers of the former were redder than the orange-red colours of the other lilies studied. Intensity of colour may be due to increase in total carotenoids but this was not so in the present study as the red L. amabile contained less (6.06 mg g-l) than the orange-red L. Davidi; var. Willmottiae (10.48 mg g-l). This is more than double the total carotenoids of the other L. Maxwill parent, L. leichtinii var. Maximowiczii (4.82 mg g-l).
A closer look at these two parents reveals that L. Davidii var. Willmottiae has more individual carotenoids than L. leichtinii var. Maximowiczii. Of the ten common to both, nine are found in the hybrid L. M axwill (later stage) i.e. p-carotene, cryptoxanthin, trans- and cis-vioiaxanthin, trans- and cis-antheraxanthin, trans-zeaxanthin, capsanthin and capsorubin, whilst neoxanthin was not found in the hybrid. The carotenoids identified in only the first parent, namely p-carotene-diepoxide, cryptoxanthin monoepoxide, cis-zeaxanthin, capsochrome and carbonyl (458 nm), and those in the second parent - phytofluene and capsanthin monoepoxide - were all found in the hybrid. Moreover p-carotene monoepoxide, trans- and cit-cryptocapsin and lutein were found only in the hybrid. This is therefore another example where pigments apparently absent in the parents were observed in the hybrid (see YOKOYAMA and WHITE, 1966).
As far as the biosynthetic pathway is concerned, all the pigments outlined in Fig. 1 were observed: some in the parents and some in the hybrid. This by itself does not necessarily mean that the pathway is the correct one but at least it indicates that this pathway is possible. The presence of lutein - albeit in small quantities - in the petals of L. M axwill is rather unexpected.
GOODWIN and WILLIAMS (1965) had presented evidence that a-carotene could not have been derived from p-carotene and vice-versa (WILLIAMS, BRITTON and GOODWIN, 1967). It is now accepted that a-carotene and p-carotene are on two different pathways and the appearance of only one carotene on the a-carotene pathway, namely lutein, is to say the least rather perplexing and cannot be explained as easily as its presence in photosynthesising leaves and fruits. In these cases members of the a-carotene series are obtained at the green stage and sometime persist for a while before disappearing completely as these organs mature (VALADON and MUMMERY, 1969). However, DAVIES, MATTHEWS and KIRK (1970) have also observed hydroxy-a-carotene and lutein in the ripe yellow fruits of C. annuum although the other carotenoids present were from the p-carotene series.
Members of the capsanthin series, that is, those carotenoids characterised by one or two acylcyclopentanol nngs, namely cryptocapsin (VI), capsanthin (IX),
z. Pjlanzenphysiol. Bd. 82. s. 407-416. 1977.
Carotenoids of lilies and of red pepper 413
capsanthin-5,6-epoxide (XII), capsochrome (XIII) and capsorubin (XIV) (Fig. 1.) appear to be formed from cryptoxanthin (IV) and zeaxanthin (VII) by a pinacolic rearrangement of their 5,6-epoxides [cryptoxanthin-5,6-epoxide (V), antheraxanthin (VIII)] and their 5,6: 5',6'-diepoxide (violaxanthin X) (WEEDON, 1971). Precursor-product relationship is well demonstrated in our results for when the precursor is high the product is low and vice-versa (antheraxanthin - capsanthin). However the same relationship is not observed between cryptoxanthin-5,6-epoxide and cryptocapsin nor between violaxanthin and capsorubin. This could indicate that these biosynthetic steps as outlined in Fig. 1. are not all the correct ones. On the other hand different amounts of precursors-products may be explained by the following: there is a rapid turnover of the precursors so that the end-products accumulate more rapidly and it is only afterwards that the precursors begin accumulating. Our results therefore are not in contradiction with the steps shown in Fig. 1. The picture with the precursor violaxanthin is rather complex in that not only does it give rise to capsanthin 5,6-epoxide then capsorubin (one end-product) but also to neoxanthin (another end-product). Under these circumstances it is rather difficult to obtain a straightforward product-precursor relationship.
The other floral parts investigated were the anthers and styles of L. Maxwill. Carotenoids found in these organs had all been observed in the petals, so no new carotenoids were identified and it may be suggested therefore that the intermediates between violaxanthin and capsorubin are as suggested previously (Fig. 1). Our results agree very closely with those of ]UNGALWALA and CAMA, (1962) in that the highest concentration of total carotenoids was in the anthers but whereas their major carotenoid was zeaxanthin (89 Ofo) ours was antheraxanthin (40 Ofo). It is interesting to note that antheraxanthin, which had been proposed as a carotenoid specifically associated with reproduction in plants and later rejected (GOODWIN, 1952), was found in such high concentrations in the anthers. On the other hand styles have capsanthin as their main carotenoid and about the same concentration of anther ax an thin as in the petals.
Carotenoids of C. annuum fruits at different stages of maturity
Five stages of fruit maturity were investigated: the green, yellow, pale orange, deep orange and red stages. The results (Table 2) show that as the fruits matured total carotenoids increased to a maximum of 2.3 mg g-l in the red fruits. In the green fruit, lutein and its epoxide on the a-carotene pathway (VALADON and MUMMERY, 1975) made up 45 % total carotenoids but these carotenoids decreased spectacularly as the fruits matured. There was then only 2.6 % total carotenoids of the a-carotene pathway in the red fruits. V ALADON and MUMMERY (1969) have shown that in maturing rose-hips members of the a-carotene series were obtained at first and also certain of the p-carotene series; antheraxanthin, violaxanthin and neoxanthin. With the disappearance of photosynthetic activity these pigments were rarely seen and very few members of the a-carotene series were found in the maturing fruit. Our
Z. Pjlanzenphysiol. Bd. 82. S. 407-416. 1977.
414 L. R. G. VALADON and ROSEMARY S. MUMMERY
Table 2: Carotenoids in Capsicum annuum fruits at different stages of maturity.
Phytofluene a-Carotene ~-Carotene ~-Zeacarotene I;-Carotene ~-Carotene-5,6-epoxide Lycopene Cryptoxan thin {'-Carotene N eurosporene Lutein-5,6-epoxide Violaxanthin cis-Lutein trans-Lutein Neoxanthin cis-Zeaxanthin trans-Zeaxanthin Flavoxanthin Capsanthin Ca psan thin -5 ,6-epoxide Capsorubin
Total carotenoids (,ug/ g)
Green
18.3
1.8 22.0
43.0 14.9
227.4
Yellow
6.3
9.0
2.3 41.3
5.9 4.8 8.0
4.6 7.5 8.8
1.5
493.3
Pale Deep Orange Orange
3.6 4.8 0.9 1.0 7.7 6.8
trace 3.8 1.5 2.0 1.1
1.4
44.7 32.4 3.2 4.6 5.4 4.6 5.2 4.9
4.2 1.3 9.3 8.1
10.5 14.2 1.7 2.5 4.2 4.4
800.4 1353.2
(values given are percentage of total carotenoids)
Red
3.9 0.5 6.9 2.1 3.6 0.9
1.2
22.9 0.8 1.3 2.4 6.2 6.2
30.7 6.3 4.1
2278.0
CPTA Treated
19.0 0.7 2.1 0.7 6.9
45.3 0.2 1.9 0.7
6.9
8.2
4.1
3.3
953.2
results with pepper fruits are almost the same as with rose-hips except that in the former anther ax an thin was never present and violaxanthin increased to a maximum and then decreased at the deep orange stage. fJ-carotene decreased apreciably as the fruits matured suggesting a central position in the synthesis of the capsanthin series (Fig. 1). Cryptocapsin identified in the ornamental pepper (DAVIES, MATTHEWS and KIRK, 1970) and in red bell peppers (CURL, 1962) and by us in lilies (present communication) was not observed in C. annuum fruits. Antheraxanthin, the immediate precursor of capsanthin, was not found either thus supporting the earlier suggestion that due to a rapid turnover of certain precursors, they only appear when the end-products have begun to accumulate. It is interesting to note here that capsanthin-S,6-epoxide only appeared at the pale orange whilst capsorubin had been identified at the preceding yellow stage and thereafter stayed fairly constant (4 %
total carotenoids). These results are therefore not in contradiction with the biosynthetic pathway of Fig. 1.
Our results agree mostly with those of DAVIES, MATTHEWS and KIRK (1970) in their work with ornamental peppers except that in our case capsanthin and capsorubin had appeared earlier at the yellow stage and not as late as at the ripe
Z. Pflanzenphysiol. Bd. 82. S. 407-416. 1977.
Carotenoids of lilies and of red pepper 415
orange stage. This is in agreement with VALADON and MUMMERY's (1972) suggestion that different strains/varieties of the same organism produce carotenoids at a different rate.
Finally, SIMPSON, RAHMAN, BUCKLE and LEE (1974) found that when different cultivars of C. annuum were treated with 2-( 4-chlorophenylthio )-ethyldiethyl-ammonium chloride (CPTA) the synthesis of capsanthin and capsorubin were inhibited. Similar observations were made on CPTA-treated fruits in the present study (Table 2). There was a complete inhibition of capsanthin and of caps an thin monoepoxide but a very small amount of capsorubin (3 0/0) was detected. What is even more interesting is that a number of carotenes not present in the normal fruits were identified, e.g. neurosporene, y-carotene and lycopene. The latter carotene always accumulates after CPTA treatment (Hsu, YOKOYAMA and COGGINS, 1972; YOKOYAMA, COGGINS and HENNING, 1971; VALADON and MUMMERY, 1974) but together with the other carotenes already observed in normal fruits, all the carotenes from phytofluence to f3-carotene had now been identified in C. annuum fruits. These results reinforce the suggested pathway of f3-carotene synthesis as proposed by several workers (VALADON and MUMMERY, 1975).
Acknowledgements
We thank Dr. H. YOKOYAMA, Pasadena, California and the firm Amchem Products, Ambler, Pa., U.S.A. for generous gifts of CPTA; and also Dr. H. THOMMEN and the firm Hoffmann La Roche, Basle, Switzerland for synthetic carotenoid samples. L.R.G.V. is grateful to Dr. ]. VILLOUTREIX, Nancy, France for the help given in identifying the ketocarotenoids present in lilies; and further thanks the Royal Society for a study visit award in their European Programme (1976).
References
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416 L. R. G. VALADON and ROSEMARY S. MUMMERY
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plastid development. II. Effect of CPTA on the ultrastructure and carotenoid composition of chromoplasts of Capsicum annuum cultivars. Aust. J. Plant Physiol. 1, 135-147 (1974).
V ALADON, L. R. G., and R. S. MUMMERY: Carotenoids in floral parts of a narcissus, a daffodil and a tulip. Biochem. J. 106, 479-484 (1968). - Changes in carotenoid composition of certain roses with age. Ann. Bot. 33, 671-677 (1969).
- - Carotenoids of Rowan berries. Ann. Bot. 36, 471-474 (1972 a). - - Chromatography of carotenoids using papers filled with silica gel and with alumina.
Phytochemistry 11, 413-414 (1972 b). - Carotenogenesis in Verticillium agaricinum in response to nicotine and to CPTA. Microbios 10 A, 97-104 (1974).
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Dr. L. R. G. VALADON and Miss R. S. MUMMERY, Department of Botany, Royal Holloway College (University of London), Egham Hill, Egham, Surrey, TW 20 OEX, England.
z. PJlanzenphysiol. Bd. 82. S. 407-416.1977.
