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POSTERS: Plant defense response

Exogenously applied ROS/RNS scavengers reduce Macrophomina phaseolina-induced lesion development in soybean and sorghum
Afsana Noor - Dept. of Plant Pathology, Kansas State University. Ananda Bandara- The Pennsylvania State University, Christopher Little- Dept. of Plant Pathology, Kansas State University

Charcoal rot, caused by the soilborne necrotrophic fungus Macrophomina phaseolina (MP), is a prevalent and economically significant plant disease. MP infection in sorghum or soybean generates excessive amounts of reactive oxygen (ROS) and nitrogen species (RNS) as a basal defense mechanism that causes cellular damage/senescence. Necrotrophs, such as MP, take advantage of this built-in cell senescence mechanism as they depend on dead tissue for nutrition. ROS/RNS generation has been validated from both hosts by transcriptomics, physiologcial assays, and exogenous application of ROS/RNS scavengers. In vitro sensitivity tests showed that MP was sensitive to sodium pyruvate, DMTU and ascorbic acid at high concentrations (50-100 mM) but not at in-planta working concentrations (10-20 mM, 0.28 M, or 100 µM). For in-planta assays, the apical portion of soybean seedlings (V2 stage) were clipped and pretreated with scavengers followed by MP inoculation. With the exception of sodium pyruvate, the scavengers showed reduced lesion development in soybean. Based on ROS scavenging by ascorbic acid in soybean, sorghum adult plants stalks were pre-treated with ascorbic acid followed by MP inoculation. Ascorbic acid reduced lesion length in sorghum adult plant. Detection and quantification of ROS/RNS and transcriptome analysis from both hosts during scavenger quenching will be performed. These experiments will be useful in understanding host resistance mechanisms against MP.