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POSTERS: Molecular plant-microbe interactions

Multi-disciplinary approaches to identify novel sources of resistance to minor-effect virulence effectors of Xanthomonas oryzae pv. oryzae
Alejandra Huerta - Colorado State University. Ana Bossa-Castro- Colorado State University, Rene Corral- Colorado State University, Emily Delorean- Colorado State University, Chitra Raghavan- International Rice Research Institute, Alvaro Perez- Colorado State University, Jan Leach- Colorado State Univ

An optimal approach to manage bacterial diseases of plants is the use ofresistant varieties. However, effective and durable disease resistance is a continuous challenge due to the pathogen’s evolution and adaptation on cultivated varieties. Xanthomonas oryzae pv. oryzae (Xoo), the causative agent of bacterial blight (BB) or rice,produces Transcription Activator-Like (TAL) effectors, which activate expression of host susceptibility genes. TAL effectors differently contribute to a strain’s virulence, and some are essential to pathogen fitness. We hypothesize that effective and durable disease resistance is attainable by targeting conserved virulence factors in the bacterium. To test this hypothesis, we used a set of indicaMulti-Parent Advanced Generation Inter-Cross (MAGIC) inbred lines, screening them for resistance against Xoostrains PXO99A and PXO99A overexpressing the conserved minor-effect TAL effector Tal7b (+Tal7b). Genome-wide association and interval mapping analyses revealed 13 disease resistance QTL, six specific to PXO99A +Tal7b and seven to PXO99A. Our data suggest that Tal7b targets more than one gene and that resistance may result from polymorphisms in the candidate Tal7b gene targets, disabling activation of the susceptibility genes. Future research will focus on the mechanism underlying these resistance phenotypes.