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Poster: Biology & Disease Mgmt: Nematology


Soybean Cyst Nematodes of Ohio: deciphering mechanisms of virulence
E. WALSH (1), T. Miller (2), A. Grenell (3), B. Cassone (4), C. Taylor (1) (1) The Ohio State University, U.S.A.; (2) The Ohio State University, U.S.A.; (3) The College of Wooster, U.S.A.; (4) Brandon University, Canada

Soybean cyst nematodes (SCN; Heterodera glycines) are the most yield-reducing pest of soybean in North America. Resistant soybean cultivars are widely utilized for management purposes, however SCN populations are quickly adapting to overused sources of resistance. Counties across Ohio were surveyed for SCN populations and their virulence against the available sources of resistance was tested with HG Type assays. Of the populations tested to date, 96% are infective on PI88788, the most prevalent source of resistance in commercial varieties. The objective of this study was to determine how SCN populations have overcome this source of resistance. Nine SCN populations from across Ohio were selected, which vary in their HG Type and/or level of virulence. These populations were grown on both PI88788 and a susceptible cultivar, Lee 74. Female SCN were harvested 15 days after inoculation with juvenile worms, total RNA was extracted, and submitted for sequencing on the Illumina Hi-Seq 2500. Interesting expression patterns were found common among virulent populations such as putative effectors and genes related to digestion, the immune response, and detoxification. Also, populations avirulent on PI88788 share the expression of an effector not present in virulent populations, indicating that the loss of this effector may play a role in virulence to this resistance source. Further work includes cloning identified candidate genes to determine their role in this interaction.