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Poster: Diseases of Plants: Disease Detection & Diagnosis


Rapid diagnostic tools for soilborne pathogens of strawberry
A. BURKHARDT (1), T. Miles (2), M. Ramon (1), S. Koike (3), F. Martin (1) (1) USDA, U.S.A.; (2) CSUMB, U.S.A.; (3) Cooperative Extension Monterey County, U.S.A.

The ability to rapidly identify and quantify strawberry pathogens in the soil allows growers to make faster decisions about what to plant and how to manage diseases a field. Therefore, we are developing rapid assays using TaqMan real-time PCR and recombinase polymerase amplification (RPA) to diagnose a variety of pathogens commonly infecting strawberry fields, including Verticillium dahliae, Fusarium oxysporum, Phytophthora spp., and Macrophomina phaseolina. These assays can provide results in hours (TaqMan) or in as little as 20 minutes (RPA) using DNA extracted from either infected plant tissue or soil. Species-specific TaqMan and RPA assays have been developed for Phytophthora and are very sensitive (0.2 pg) and specific. For V. dahliae, a species-specific TaqMan assay with a sensitivity of 1-2 microsclerotia per gram of soil is being converted to an RPA assay. Host-specific markers for F. oxysporum f. sp. fragariae are currently being developed for both TaqMan and RPA using a locus previously published by Suga et al. (Plant Dis. 2013). Additional loci for F. oxysporum f. sp. fragariae are being identified through sequencing and comparative genomics of multiple isolates in order to expand the breadth of detection. For M. phaseolina, sequencing of multiple isolates has identified a genotype-specific locus, and primers are being developed for RPA and TaqMan assays to detect isolates which have been found to only infect strawberry.