1. Effects of Altering Three Steps of Monolignol Biosynthesis on Sorghum Responses to Stalk Pathogens and Water Deficit.
- Author
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Funnell-Harris DL, Sattler SE, O'Neill PM, Gries T, Ge Z, and Nersesian N
- Subjects
- Edible Grain, Mutation, Sorghum genetics, Sorghum microbiology, Ascomycota
- Abstract
The drought-resilient crop sorghum ( Sorghum bicolor [L.] Moench) is grown worldwide for multiple uses, including forage or potential lignocellulosic bioenergy feedstock. A major impediment to biomass yield and quality are the pathogens Fusarium thapsinum and Macrophomina phaseolina , which cause Fusarium stalk rot and charcoal rot, respectively. These fungi are more virulent with abiotic stresses such as drought. Monolignol biosynthesis plays a critical role in plant defense. The genes Brown midrib ( Bmr ) 6 , Bmr12 , and Bmr2 encode the monolignol biosynthesis enzymes cinnamyl alcohol dehydrogenase, caffeic acid O -methyltransferase, and 4-coumarate:CoA ligase, respectively. Plant stalks from lines overexpressing these genes and containing bmr mutations were screened for pathogen responses with controlled adequate or deficit watering. Additionally, near-isogenic bmr12 and wild-type lines in five backgrounds were screened for response to F. thapsinum with adequate and deficit watering. All mutant and overexpression lines were no more susceptible than corresponding wild-type under both watering conditions. The bmr2 and bmr12 lines, near-isogenic to wild-type, had significantly shorter mean lesion lengths (were more resistant) than RTx430 wild-type when inoculated with F. thapsinum under water deficit. Additionally, bmr2 plants grown under water deficit had significantly smaller mean lesions when inoculated with M. phaseolina than under adequate-water conditions. When well-watered, bmr12 in cultivar Wheatland and one of two Bmr2 overexpression lines in RTx430 had shorter mean lesion lengths than corresponding wild-type lines. This research demonstrates that modifying monolignol biosynthesis for increased usability may not impair plant defenses but can even enhance resistance to stalk pathogens under drought conditions., Competing Interests: The author(s) declare no conflict of interest.
- Published
- 2023
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