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POSTERS: Biological control

Enhanced hypovirus transmission by engineered super donor strains of the chestnut blight fungus, Cryphonectria parasitica, in a forest setting
Matthew Kasson - West Virginia University, Division of Plant and Soil Sciences. Amy Metheny- West Virginia University, Cameron Stauder- West Virginia University, William MacDonald- West Virginia University, Mark Double- West Virginia University, Dong-Xiu Zhang- Institute for Bioscience and Biotechnology Research, University of Maryla

Horizontal transmission of virulence attenuating hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced hypovirus vector for highly divergent C. parasitica populations. Ongoing studies are focused on optimizing delivery of SD strains including several application methods and hypoviruses to further reduce canker expansion in a forest setting.