Poster Session: Epidemiology - Population Biology Genetics
631-P
Forensic application of SSR typing to identify probable sources of Fusarium proliferatum strains associated with salmon blotch of onions.
I. R. Moncrief (1), C. D. Garzon (2), S. M. Marek (2), A. Gamliel (3), J. P. Stack (4), Y. Isack (3), J. FLETCHER (2)
(1) Harry S. Truman College, Chicago, IL, U.S.A.; (2) Oklahoma State University, Stillwater, OK, U.S.A.; (3) ARO Volcani Institute, Bet Dagen, Israel; (4) Kansas State University, Manhattan, KS, U.S.A.
Microbial forensics tools can help to identify potential pathogen sources. Since 2008, unprecedented outbreaks of salmon blotch of onion, caused by the mycotoxigenic fungus Fusarium proliferatum (Fp), have occurred in southern Israel. Though presumed to be of natural causes, the disease allowed us to validate plant pathogen forensic tools in a field application. To test whether onion sets grown in northern Israel and shipped to southern farms for planting could be a source of the fungus, the diversity and structure of Fp populations from different locations and sample matrices were assessed by simple sequence repeat (SSR) typing. Fp isolates (n=216) from onion sets, field soil, nearby date palm orchards, weeds, local vegetation, and onion bulbs were characterized. Of 17 SSR loci screened with genomic DNA from all Fp isolates, six amplified a range of isolates from different locations and hosts. Resulting PCR amplicons were analyzed by capillary electrophoresis. Data analysis (UPGMA, AMOVA, and STRUCTURE) revealed two distinct Fp populations: 1) northern Israel isolates from onion sets, and 2) southern Israel isolates from onion bulbs, soil, weeds, or palm trees. That the two populations were genetically distinct eliminates the northern-grown onion sets as the source of the Fp causing salmon blotch in southern Israel. The work demonstrated that SSR typing is useful for fungal strain discrimination and can be useful for forensic investigation of plant diseases.