ARS | Publication request: The role of phenylpropanoid pathway metabolites in resistance of sorghum to pathogens

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 7, 2011
Publication Date: September 16, 2011
Citation: Funnell-Harris, D.L., Sattler, S.E., Prom, L.K., Pedersen, J.F. 2011. The role of phenylpropanoid pathway metabolites in resistance of sorghum to pathogens. Meeting Abstract. Presentation.

Technical Abstract: Sorghum is being developed for diverse uses, including for bioenergy and food. In order to increase efficiency of ethanol production from plant materials, sorghum lines with reduced lignin were developed by incorporating two mutations in lignin biosynthesis pathway genes: brown midrib (bmr) 6 and bmr12. Some of these low lignin lines had unexpected responses to grain mold pathogens. Grain collected from bmr and near-isogenic wild-type plants grown at two field locations at Lincoln and Ithaca, NE, were screened for Fusarium infection. Most commonly isolated from wild-type grain were two pathogens, Fusarium thapsinum and Fusarium proliferatum, and two Fusarium incarnatum-F. equiseti (FIESC) species complex genotypes: 25-a,b,c and 18-a,b,c. These four species also were detected in bmr6 grain but FIESC 25-a,b,c was absent from bmr12 grain and F. proliferatum was reduced, indicating that bmr12 resulted in reduced grain infection by Fusarium species. Also tested was the hypothesis that purple pigment protects sorghum against grain mold and head smut. Anthocyanin pigments, associated with purple wounding response and disease resistance, are lacking in tan plants, preferred for food-grade white grain production. Near-isogenic purple and tan plants, with white grain, were grown at Corpus Christi, TX, and Lincoln and Ithaca, NE. When screened for Alternaria, Fusarium, and Curvularia species, grain from purple and tan plants had similar numbers of these fungi. At Corpus Christi, panicles were also assessed for incidence of head smut disease, caused by the fungus Sporisorium reilianum. Surprisingly, head smut incidence on tan plants was significantly lower than on near-isogenic purple plants. These results indicate that lines with reduced anthocyanin pigments or lignin are viable choices for sorghum grain production, regarding protection against head smut or grain mold diseases, respectively.