Demonstration of pathogenicity in three different Magnaporthe oryzae isolates

Abstract

In present study, three Magnaporthe isolates were analyzed for understanding pathogenicity of blast disease in rice. M oryzae 6808 and M oryzae ch1 isolates produced pyriform shaped macroconidia and were able to form appressoria under artificial condition. M oryzae 6926 produced crescent shaped microconidia but failed to produce appressoria in the similar condition. Pathogen inoculation assay results showed that all three Magnaporthe isolates were infective with varying degree of infection. Pathogen isolates produced spindle shaped lesion with necrotic borders on different cultivars of paddy lines with different disease intensity. Both types of sporulation contributed to disease incidence and disease severity in rice lines. Entry of pyriform shaped macroconidia and formation of appressoria in suitable host plant has been widely studied. Likely, there must be another mechanism for crescent shaped microconidia to make entry into host cell to cause disease symptoms in suitable host plant. It was observed that pathogenicity in rice was caused due to macroconidia and microconidia both. Microconidial infection needs to be further explored in understanding blast disease cycle.