Location: Wheat, Sorghum and Forage ResearchTitle: Response of sorghum enhanced in monolignol biosynthesis to stalk pathogens
|CLEMENTE, THOMAS - University Of Nebraska|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2019
Publication Date: 9/1/2019
Citation: Funnell-Harris, D.L., Sattler, S.E., O'Neill, P.M., Gries, T.L., Tetreault, H.M., Clemente, T.E. 2019. Response of sorghum enhanced in monolignol biosynthesis to stalk pathogens. Plant Disease. 103(9):2277-2287. https://doi.org/10.1094/PDIS-09-18-1622-RE.
Interpretive Summary: To expand sorghum biomass for thermochemical bioenergy uses, lines were developed that have increased total energy by increasing lignin or other high energy components of the plant. Lines were developed that had higher levels of proteins needed for lignin synthesis. It is important to know whether these lines are also resistant to diseases that could reduce biomass yield, such as stalk rots. To test whether the experimental lines were as resistant as normal plants to the destructive diseases Fusarium stalk rot and charcoal rot, the new lines (three called SbMyb, and two each of SbCCoAOMT, SbPAL, Sb4CL and SbC3H) were tested in the greenhouse against the fungi that cause these diseases. Two SbMyb60 lines, and one SbCCoAOMT line, had reduced Fusarium stalk rot, as compared to normal plants. One line, called SbPAL, had more charcoal rot disease than normal plants. All other lines were as resistant to the diseases as the normal cultivar. The SbMyb and SbCCoAOMT lines also were tested in the field against Fusarium stalk rot and the results were similar for SbMyb60 lines to those from the greenhouse studies, but SbCCoAOMT lines were more susceptible than the normal plants under field conditions. This information will help develop stalk rot disease-resistant sorghums for alternative bioenergy uses.
Technical Abstract: To increase phenylpropanoid constituents and energy content in the versatile C4 grass sorghum [Sorghum bicolor (L.) Moench], sorghum genes for proteins related to monolignol biosynthesis were overexpressedrot : SbMyb60 (transcriptional activator), SbPAL (phenylalanine ammonia lyase), SbCCoAOMT (caffeoyl coenzyme A 3-O-methyl transferase), Bmr2 (4-coumarate:CoA ligase), and SbC3H (coumaroyl shikimate 3-hydroxylase). Overexpression lines were evaluated for responses to stalk pathogens under greenhouse and field conditions. Greenhouse-grown plants were inoculated with Fusarium thapsinum (Fusarium stalk rot) and Macrophomina phaseolina (charcoal rot) that cause yield-reducing diseases. Fusarium thapsinum-inoculated overexpression plants had mean lesion lengths not significantly different than wild-type, except for significantly smaller lesions on two of three SbMyb60 and one of two SbCCoAOMT lines. Macrophomina phaseolina-inoculated overexpression lines had lesions not significantly different from wild-type except one (of two) SbPAL line with mean lesion significantly larger. Field-grown SbMyb60 and SbCCoAOMT overexpression plants were inoculated with F. thapsinum. Mean lesions of SbMyb60 lines were similar to wild-type but one SbCCoAOMT had larger lesions, while the other line was not significantly different than wild-type. Because overexpression of SbMyb60, Bmr2 or SbC3H may not render sorghum more susceptible to stalk rots, these lines may provide sources for development of sorghum with increased phenylpropanoid concentrations.