Archivio Journal of Plant Pathology

Abstract:

Seventyfive monoconidial isolates of Magnaporthe grisea species complex were obtained from rice and some grasses from north Iran during 1997-2005. Thirtyfive isolates were from rice and 40 from crabgrass, foxtail millet, barnyard millet, and some unknown weeds. All these isolates and eight standard mating type tester isolates were analyzed with complementation tests using nitrate non-utilizing (nit) mutants to determine vegetative compatibility groups (VCGs) and genetic relationship between the two groups of isolates. All rice isolates were grouped into four VCGs designated as VCG1, VCG2, VCG3, and VCG4. VCG3 was the most common group and included 14 isolates, whereas the isolates obtained from grasses belonged to three different multimember VCGs, denoted VCG5, VCG6, and VCG7. VCG5 included 29 isolates out of 40 and other two multimember VCGs contained four isolates each. Results showed that although Magnaporthe populations infecting rice and gramineae weeds share a common ancestry, no vegetative compatibility was observed between them. This study also indicated that there is no correlation between field isolates and standard mating type isolates. Thus, determination of VCGs is a useful mean for characterizing genetic diversity within and among all Magnaporthe species from different hosts.