وضعيت باروري و تيپ آميزشي cochliobolus miyabeanus, عامل بيماري لكه قهوه اي برنج دراستان گيلان

FERTILITY STATUS AND MATING TYPE OF Cochliobolus miyabeanus, THE CAUSAL AGENT OF RICE BROWN SPOT DISEASE IN GUI LAN PROVINCE

An investigation was carried out to determin fertility status and mating type of Cochliobolus miyabeanus, the causal agent of brown spot of rice disease, in Guilan province. A total of one hundred and forty-seven isolates of Cochliobolus miyabeanus were collected in spring and summer of 2007-2008 from different rice growing areas of Guilan province. The pathogen was isolated from infected leaves and seeds on potato dextrose agar and purified by monoconidial isolation. Isolates were selfed and mated in all possible combinations. According to the result, all of the isolates were self-sterile and only 23.8% of isolates were fertile. Thirty-five isolates were placed in two arbitrary mating type A and a that 17 isolates were female-fertile and 18 isolates were male-fertile. Ascospores germination ability was examined on water and water agar under laboratory condition. Ascospores from all of the fertile isolates were able to germinate.