Host-specificity and sexual compatibility of Pyricularia oryzae isolated from different hosts in Iran

Pyricularia oryzae is rice and wheat blast causal agent and can occurs leaf spot on some grass species. Blast disease is one of the most important diseases in rice areas cultivated in Iran, annually it cause economic damage to rice. Sampling was conducted from rice, maize, foxtail millet, and weeds of wheat and rice cultivation regions, citrus orchards, and jungles in southern of Caspian Sea and from rice fields in Khorasan-razavi province during summers of 2013 and 2015. Phylogenetic analysis with partial regions of Actin (ACT), Calmodulin (CAL), and RNA polymerase II largest subunit genes (Rpb1) allowed to assign the strains from different hosts to Pyricularia oryzae. Pathogenicity test of P. oryzae species was applied on rice, foxtail millet, maize, barnyard grass, and wild foxtail millet in control condition. Based on pathogenicity, each isolate were highly pathogenic toward its host but not to the other hosts tested. In order to a determination of mating type, Multiplex PCR technique using primers L1 and L2 (for Mat1-1), T1, and T2 (for Mat1-2) was done. Under lab conditions, the sexual stage was conducted with isolates from different hosts on rice flour- agar medium. The mating type and sexual reproduction show that Mat1-1 is frequent in rice population and foxtail millet population and Mat1-2 is frequent in weeds populations and maize population.