Location: Wheat, Sorghum and Forage Research
Title: Effects of altering three steps of monolignol biosynthesis on sorghum responses to stalk pathogens and water deficitAuthor
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 5/15/2023 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The drought-resilient crop sorghum [Sorghum bicolor (L.) Moench] is grown for forages and has potential for lignocellulosic bioenergy. A major impediment to biomass yield and quality are Fusarium thapsinum and Macrophomina phaseolina that cause Fusarium stalk rot and charcoal rot, respectively. These diseases are especially damaging during drought. Monolignol biosynthesis plays a critical role in plant defense. Brown midrib (Bmr)6, Bmr12, and Bmr2 encode monolignol biosynthesis enzymes cinnamyl alcohol dehydrogenase, caffeic acid O-methyltransferase, and 4-coumarate:CoA ligase, respectively. Lines overexpressing these genes or containing corresponding loss-of-function mutations were screened for pathogen responses using controlled adequate or deficit watering. All mutants and overexpression lines were no more susceptible than wild-type lines in both watering conditions. In water deficit, bmr2 and bmr12 near-isogenic lines had significantly shorter mean lesion lengths than wild-type variety RTx430 when inoculated with F. thapsinum. The bmr2 plants grown under water deficit had significantly shorter mean lesions when inoculated with M. phaseolina than those grown under adequate water. When well-watered, bmr12 in variety Wheatland and one of two Bmr2 overexpression lines in RTx430 had shorter mean lesion lengths than corresponding wild-type lines. This research shows that modifying monolignol biosynthesis for increased usability may not impair plant defenses, and may even enhance resistance to stalk pathogens under drought conditions. |
