Changes in phenylpropanoids in two sweet sorghum lines differing with contrasting responses to stalk pathogens

Authors: Funnell-Harris, Deanna; KHASIN, MAYA - Former ARS Employee; Bernhardson, Lois; O`Neill, Patrick; Palmer, Nathan - Nate; Scully, Erin; Sattler, Scott; Sarath, Gautam

Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/4/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Sweet sorghum [Sorghum bicolor (L.) Moench] lines M81-E and Colman differed in responses to stalk rot pathogens Fusarium thapsinum and Macrophomina phaseolina: M81-E had shorter mean lesion lengths than Colman when inoculated with either fungus. The transcriptional and secondary metabolic responses to pathogen and mock inoculations were examined at 3 and 13 days after inoculation (DAI) in plants of these lines. Transcripts encoding monolignol biosynthetic and modification enzymes were associated with mock responses of both lines at 3 DAI. Monolignol biosynthetic genes were coexpressed with transcriptional activator SbMyb76 in all Colman inoculations, but only after M. phaseolina inoculation in M81-E. In mock-inoculations, defense-related genes were expressed at higher levels in M81-E than Colman. Line, treatment, and timepoint differences in phenolic metabolites did not account for lesion differences. Generalized additive models could relate metabolites to lesion length and quantitatively model disease progression. Only in M81-E, sinapic acid levels positively predicted lesions at 3 DAI when cell wall-bound syringic acid was low and soluble caffeic and lactic acids were high. These results provide potential gene targets for development of stalk rot resistant sweet sorghum varieties with high yields and quality of biomass and sugar.