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Oral: Novel Applications of Whole Genome Sequencing and Bioinformatics in Microbial Forensics and Agricultural Biosecurity


Microbial Forensics Case Study: Applications of Forensic Technology in a Field Outbreak of Salmon Blotch of onion.
J. FLETCHER (1), J. Fletcher (2), I. Moncrief (3), U. Melcher (2), A. Gamliel (4), J. Stack (5) (1) Department of Entomology & Plant Pathology, Oklahoma State University, U.S.A.; (2) Oklahoma State University, U.S.A.; (3) Harry S. Truman College, U.S.A.;

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Forensic tools were developed and applied to investigate an actual outbreak, in Israel, of salmon blotch disease of onions, caused by Fusarium proliferatum. A decision tool designed to assist investigators recognize signs of criminal activity at the field was implemented. F. proliferatum was isolated from onions and soil from the affected field, nearby fields and natural vegetation in southern Israel onion production areas, and from onion sets, grown in northern Israel and shipped for planting in southern fields, to test whether the fungus was disseminated on the sets. SSR analyses revealed that fungal populations from onion sets (northern Israel) are genetically distinct from those in southern Israel. F. proliferatum populations from southern field soils are similar to one another and to those from bulbs at each southern field. Further, F. proliferatum isolates from volunteer salt cedars in the onion fields are clonal and indistinguishable from those from the southern field soil and white onion bulbs. The findings suggest that onion sets from northern Israel are not the source of the F. proliferatum causing onion salmon blotch in southern Israel. Volunteer weeds, including salt cedar, and previously contaminated field soil could serve as alternative reservoirs for the fungus, from which inoculum could have moved to the onions. This work validated the use of microbial forensic tools, in both laboratory and field settings, for investigation of a plant disease.