STUDY ON EFFECT OF HYPHAL ANASTOMOSIS BETWEEN AFLATOXIGENIC AND NON-AFLATOXIGENIC STRAINS OF Aspergillus flavus ISOLATED FROM PISTACHIO ON REDUCTION OF AFLATOXIN PRODUCTION AND ANALYSIS OF PRODUCED HETEROKARYONS USING REP-PCR

Contamination of pistachio fruits by aflatoxin-producing isolates of Aspergillus flavus has caused critical problems in pistachio production, consumption and exportation in Iran. In order to study aflatoxin production rate in A. flavus isolates collected from pistachio fruits, 46 isolates of the fungus were tested using ELISA method. 80.44 percent of isolates produced aflatoxin and 19.56 percent of isolates were non-aflatoxigenic. Moreover, to study the effect of hyphal anastomosis on the reduction of aflatoxin production by heterokaryon isolates, toxigenic and non-toxigenic mutants R5 and Mb2 were crossed, respectively. Among the 30 heterokaryon isolates, only ten percent of isolates were not able to produce aflatoxin. Results showed that hyphal anastomosis can affect reduction of aflatoxin production in heterokaryon isolates. Also, the results of DNA fingerprinting patterns, resulting from rep-PCR, showed that all parental isolates (R5 and Mb2) had similar patterns except for one fragment with the size of 566 bps. Also, fingerprinting patterns for heterokaryons isolates (R5Mb21 to R5Mb215) were similar to those of toxigenic parents (R5).