Response of near isogenic sorghum lines, differing at the P locus for plant

color, to grain mold and head smut fungi

Deanna Funnell-Harris

Jeff PedersenPlant Geneticist

John ToyAgronomist

Pedersen, J. F., Toy, J. J. (2001) Germination, emergence and yield of 20 plant color, seed-color near-isogenic lines of grain sorghum. Crop Science, 41, 107-110.

Purple Tan

Red “White”

• There were no significant differences in mean lesion lengths when tan or purple plants (with red or white grain) were inoculated with Fusarium thapsinum or Alternaria sp.

• When assessing grain grown on purple or tan plants, results indicated that purple plant color may protect grain from Fusarium pathogens.

• Hypothesis: Purple plant color protects grain against panicle diseases.

Funnell, D. L., Pedersen, J. F. (2006) Association of plant color andpericarp color with colonization of grain by members of Fusarium and Alternaria in near-isogenic sorghum lines. Plant Disease, 90, 411-418

• Grain with white pericarps grown on tan plants has a neutral flavor, appealing appearance and higher digestibility.

• Grain grown on purple or red plants results in an off-color.

Bach Knudsen et al., 1988Dykes et al., 2005Rooney & Awika, 2005

Louis Prom Scott Sattler Jeff Pedersen

Phenylalanine

Cinnamic acid

p-Coumaric acid

p-Coumaryl Coenzyme A …P?

Snyder and Nicholson. 1990. Science 248: 1637-1639Lo and Nicholson. 1998. Plant Physiol. 116: 979-989Vermeriss and Nicolson. 2008. Phenolic Compound Biochemistry

3-DeoxyanthocyanidinsAnthocyanidins

Anthocyanins

Naringenin

Lignin biosynthesis

Flavonoidbiosynthesis

Sorghum pigment geneticsPlant color-two loci P and Q

-P-purple plant color-p-tan plant color-Q-purplish-black-P is epistatic over Q

Pericarp color-two loci R and Y-RRYY-red-rrYY-yellow-RRyy, rryy-white

• Plant color lines– Purple-PPQQ– Tan-ppQQ– Grain-RRyy

Purple Tan

White grain

Rooney. 2000. Pages 261 – 307 In Sorghum: Origin, History, Technology and ProductionZanta et al. 1994. Journal of Heredity, 85, 23 - 29

Experiment

• Ten near-isogenic lines, 5 producing the purple/red pigments (“purple”), 5 not (“tan”) all with white grain.

• Planted in 4 replica plots 2 (Lincoln and Ithaca, NE) or 3 (Corpus Christi, TX) years.

• Collected grain, assessed for grain mold fungi.• At CC assessed for incidence of head smut

symptoms and signs.

Funnell-Harris, D. L., Prom, L. K., Sattler, S. E. and Pedersen, J. F. 2013. Ann. Appl. Biol., 163, 91-101

Grain mold fungiAlternaria

A. alternataA. tenuissima

Fusarium G. fujikuroiOther Fusarium

Cochliobolus spp.Curvularia lunataCu. sorghinaBipolaris sorghicola

Kindly provided by S. Navi

Little and Magill. 2003. Physiol. Mol. Plant Pathol. 63: 271-279.Funnell-Harris et al. 2010. Phytopathology 100: 671-681Funnell-Harris et al. 2013. Can. J. Microbiol. 59: 87-96

Mean numbers and standard errors of Alternaria spp. colonies per 100 grains, by selection on DCPA or DRBC media, obtained from grain grown on purple or tan sorghum plants at three locations.y

Fungal group MediumzLocation Plant color

Ithaca Lincoln Corpus Christi Purple Tan

Total Alternaria spp.

DCPA 51.7 ± 14.3 51.5 ± 14.2 46.2 ± 14.4 50.7 ± 8.7 49.1 ± 8.8

P = 0.951 P = 0.749

DRBC 53.9 ± 14.9 53.1 ± 14.8 45.9 ± 14.9 51.4 ± 8.8 50.5 ± 8.8

P = 0.920 P = 0.786

A. alternata DCPA 35.1 ± 13.0 38.9 ± 13.0 34.0 ± 13.1 37.8 ± 7.7 34.2 ± 7.7

P = 0.963 P = 0.317

DRBC 37.9 ± 13.7 40.7 ± 13.7 33.1 ± 13.8 36.8 ± 8.0 37.6 ± 8.0

P = 0.927 P = 0.777

yLeast squares means were compared within location or plant color, for medium selected upon

zGrains were screened for fungal growth by plating onto the media, dichloran chloramphenicol peptone agar (DCPA) and dichloran, rose bengal, chloramphenical (DRBC) agar.

Numbers of Alternaria isolation per 100 grains: no significant differences

Funnell-Harris, D. L., Prom, L. K., Sattler, S. E. and Pedersen, J. F. 2013. Ann. Appl. Biol., 163, 91-101

Location effects and medium × plant color interactions on colonization of

grain by Cochliobolus spp.Mean numbers and standard errors of Cochliobolus spp. colonies per 100 grains, as determined by selection on DCPA or DRBC media, obtained from grain grown on purple or tan sorghum plants at three locations.y

MediumzLocation Plant color

Ithaca Lincoln Corpus Christi Purple Tan

DCPA 0.3 ± 0.3 0.3 ± 0.3 3.2 ± 1.1 0.5 ± 0.5 2.0 ± 0.5

P = 0.058 P = 0.052

DRBC 0.3 ± 0.8 1.5 ± 0.8 4.3 ± 0.8 2.9 ± 0.8 1.2 ± 0.5

P = 0.010 P = 0.063

yLeast squares means were compared within location or plant color, for medium selected upon.zGrains were screened for fungal growth by plating onto the media, dichloran chloramphenicol peptone agar (DCPA) and dicholoran, rose bengal, chloramphenical agar (DRBC).

Funnell-Harris, D. L., Prom, L. K., Sattler, S. E. and Pedersen, J. F. 2013. Ann. Appl. Biol., 163, 91-101 Funnell-Harris, D. L., Prom, L. K., and Pedersen, J. F. 2013. Can. J. Microbiol., 59, 87-96

Location effects on colonization of grain by Fusarium species but no effects of

plant colorMean numbers and standard errors of Fusarium spp. per 100 grains, by selection on DCPA, DRBC and PCNB media, obtained from grain grown on purple or tan sorghum plants at three locationsw.

MediumxLocation Plant color

Ithaca Lincoln Corpus Christi Purple Tan

DCPA 1.3 ± 1.2 1.3 ± 1.0 5.7 ± 1.8 3.4 ± 1.0 2.1 ± 1.0

P = 0.204 P = 0.272

DRBC 3.7 ± 2.7 1.1 ± 2.6 6.0 ± 2.9 3.9 ± 1.8 3.3 ± 1.7

P = 0.721 P = 0.237

PCNB 0.3 ± 0.3 0.7 ± 0.4 3.3 ± 0.9 1.8 ± 0.5 1.0 ± 0.5

P = 0.015 P = 0.253wLeast squares means were compared within location or plant color, for the fungal group and medium.xGrains were screened for fungal growth by plating onto the media, dichloran chloramphenicol peptone agar (DCPA), dicholoran, rose bengal, chloramphenical agar (DRBC) and pentachloronitrobenzene agar (PCNB).

Funnell-Harris, D. L., Prom, L. K., Sattler, S. E. and Pedersen, J. F. 2013. Ann. Appl. Biol., 163, 91-101

Two pathogenic species were detected in grain grown at all three locations.

Known Fusarium sorghum pathogens isolated from grain grown on purple or tan plants, at three locations, identified using a molecular identification technique.

Location SpeciesyPurple plant color Tan plant color

% similarity n % similarity n

Ithaca, NE F. proliferatum 99 1 100 1

F. thapsinum 99 3 99 4

Lincoln, NE F. andiyazi 100 1 Not tested

F. proliferatum 99-100 2

F. thapsinum 99 3

Corpus Christi, TX F. proliferatum 99 1 100 1

F. thapsinum 99 7 99 4

F. verticillioides 100 1 n/a 0

yThe 5’ region of the translation elongation factor gene (TEF) was amplified and sequenced and compared with sequences of type isolates in the FUSARIUM-ID database (http://isolate.fusariumdb.org/index.php).

F. thapsinum

Funnell-Harris, D. L., Prom, L. K., Sattler, S. E. and Pedersen, J. F. 2013. Ann. Appl. Biol., 163, 91-101

Base changes in TEF

F. proliferatum

Conclusion-grain mold

• Grain from purple plants was not more resistant to the three grain mold fungal genera than grain grown on tan plants.

Sorghum head smut (Sporisorium reilianum)

Frederiksen. 2002. Pages 18-20 In “Compendium of Sorghum Diseases”

At Corpus Christi, purple plants had greater head smut incidence than tan

plants

Mean incidence (percent plants affected) of head smut in plants near-isogenic for plant colorPlant color Percent head smut

Purple 14.8*

Tan 6.8

SE for means are 2.4.Means are significantly different at P < 0.001.

Phenylalanine

Cinnamic acid

p-Coumaric acid

p-Coumaryl Coenzyme ALignin

biosynthesis…P?

Snyder and Nicholson. 1990. Science 248: 1637-1639Lo and Nicholson. 1998. Plant Physiol. 116: 979-989Vermeriss and Nicolson. 2008. Phenolic Compound BiochemistryPedersen and Toy. 2001. Crop Sci. 41: 107 - 110Cui et al. 1996. Physiol. Mol. Plant Pathol. 49: 187-199.Halkier and Moller. 1989. Plant Phys. 90: 473-479.

Phenylalanine ammonia lyase

Chalcone synthase?

3-DeoxyanthocyanidinsAnthocyanidins

Anthocyanins

Naringenin?

Flavonoidbiosynthesis

Conclusions

• The near-isogenic purple and tan lines with white grain are potentially valuable to investigate other defenses of sorghum besides the well-characterized 3-deoxyanthocyanidin phytoalexins.

• The tan lines would be ideal to develop food-grade sorghum hybrids, especially in combination with lines having race-specific resistance to sorghum head smut.

Deanna Funnell-HarrisPlant pathologist

Scott SattlerPlant molecular biologist

USDA-ARS Sorghum project, Lincoln, NE

Melinda YerkaPlant geneticist

National Institute of Food & Agriculture, grant 2011-67009-30026