HYBRIDIZATION OF GENES INVOLVED IN AFLATOXIN BIOSYNTHESIS TO DNA OF AFLATOXIGENIC AND NON-AFLATOXIGENIC ASPERGILLI

Southern blots of DNA from a number of aspergilli belonging to Aspergi llus section Flavi, including aflatoxin-producing and non-aflatoxigeni c isolates of A. flavus and A. parasiticus, were probed with the aflat oxin pathway genes aflR and omt-1. DNA of all A. flavus, A. parasiticu s and A. sojae isolates examined hybridized with both genes. None of t he A. oryzae isolates examined hybridized to the aflR probe and one of the three did not hybridize to the omt-1 probe. None of the A. tamari i isolates examined hybridized to either gene. Our results suggest tha t some isolates in this section do not produce aflatoxin because they lack at least one of the genes necessary for biosynthesis, and that no n-producing A. flavus, A. parasiticus and A. sojae strains either lack a gene we did not examine or have genes that are not being expressed.