A Study on the Genetic Diversity and Sexual Fertility Status of Magnaporthe grisea Isolates Obtained from Different Weeds of Poaceae and Rice

A determination of the genetic variation of the fungus isolated from graminous weeds which is highly beneficial to know probable genetic recombination in the fungus populations was done for the first time in Iran through PCR reaction. The isolates of fungus “Magnaporthe grisea” from graminous weed hosts and from rice were analyzed through RAPD-PCR to assay the mating type and genetic diversity.Using three random primers of: I, D and H, DNA fragments of 42 isolates were amplified from 220bp to 2500bp. Using cluster analysis and data comparison as based on Dice coefficient four clonal lineages and 20 haplotypes were identified. Similarity of 20% “A” clonal lineage including 29 isolates recovered from Digitaria sp. as well as isolates recovered from unknown weed hosts with “B”,“C” and “D” clonal lineages (including isolates recovered form Setaria sp. Echinocloa sp. of rice isolates) indicates distant relationship of “A” clonal lineage with the other clonal lineages. Forty-eight single-spored isolates of weeds and of rice were crossed with eight fertile hermaphrodite standard isolates on medium culture assay the mating type. Among Echinochloa sp. and Setaria sp. isolates Mat1-1 and among isolates of Digitaria sp. Mat1-2 were the dominant ones. Mating type of isolates recovered from rice was determined as Mat1-1. Weed isolates especially isolates obtained from Setaria sp. had high fertility as all Setaria sp. isolates produced ascospores in crosses. Mating type of 34 isolates was determined using PCR technique and two pairs of specific primers by the names of L1, L2,T1 and T2 verified the results of the mating experiments.