Genetic characterization of Aspergillus flavus soil populations in Kenya using simple sequence repeat (SSR) markers
M. S. ISLAM (1), K. A. Callicott (1), K. T. Meyers (2), R. Bandyopadhyay (3), C. Mutegi (4), P. J. Cotty (1). (1) USDA-ARS, Tucson, AZ, U.S.A.; (2) School of Plant Sciences, The University of Arizona, Tucson, AZ, U.S.A.; (3) International Institute of Tropical Agriculture, Ibadan, Nigeria; (4) International Institute of Tropical Agriculture, Nairobi, Kenya
Human populations in Kenya are frequently exposed to dangerous levels of aflatoxins. Biocontrol products based on atoxigenic isolates of <i>Aspergillus flavus</i> are the most effective management tools for preventing aflatoxin contamination. Aflasafe KE01, containing four atoxigenic isolates, is under development for prevention of aflatoxin contamination in Kenya. The four isolates in KE01 were originally isolated from maize produced in Kenya, and each belongs to a distinct vegetative compatibility group with characteristic simple sequence repeat (SSR) haplotypes. However, natural distributions of these isolates beyond grain produced in 2004 to 2006 have not been studied. Prior to initial treatment of farmer’s fields with KE01 in 2012, soil samples were collected from 287 farms in 13 districts located in 5 Kenya counties: Embu (68 farms /2 districts), Kitui (47/3), Machakos (65/4), Makueni (67/3) and Tana River (40/1). Isolates (1070) recovered from these soils were characterized with 17 SSR markers with 8 to 62 alleles. A total of 892 haplotypes (out of a possible 4.7 x 1023 combinations under random assortment) were detected; 97 of these were displayed by two or more isolates (2 to 16). Most haplotypes detected multiple times were geographically restricted, but 27% occurred in two or more of the five districts. Haplotypes of three of the four KE01 isolates were detected in the farm soils, with one KE01 haplotype being found in the most samples (2.1%) and districts (5).
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