Fertility status and distribution of mating type alleles of M. grisea were studied in some rice growing areas of Mazandaran. One hundred and seventy monoconidial isolates were isolated from different cultivars of rice in various areas. Fertility status and mating type of each isolate were determined through pairing with hermaphroditic standard isolates of mat1-1 and mat1-2 on rice flour agar (RFA). Cultures were incubated for10-25 days at 21°C under continuous illumination. Globose perithecia of long neck were formed at the contact line of two isolates’ about 10-25 days after incubation in these conditions. Of the 170 isolates, 131 (about 79%) were fertile, all male-fertile, carrying just mat1-1 allele. About 21% of the isolates were sterile and did not produce visible perithecia in pairing with all the standard isolates. No examined isolate carried mat1-2 allele.With regard to that only, one mating type allele was found in the rice growing areas of Mazandaran, all the isolates being male-fertile, formation of the perfect state among rice isolates seeming to be impossible or very rare.
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