Classification and parasitic specialization of blast fungi

Pyricularia oryzae (Magnaporthe oryzae), a causal agent of blast diseases on staple gramineous crops, is a model organism listed as the most important economically and scientifically of the top 10 fungal pathogens by fungal molecular pathologists. Although we are now in an era of genome-enabled analysis, we need to understand the history of the pathogen’s taxonomy, classification, and parasitic specialization in addition to recent research advances. In this review, we focus on these rather fundamental topics. First, the history of classification, including the discovery of its sexual stage and designation, is overviewed. Based on recent results of phylogenetic analysis of Magnaporthaceae isolates, blast fungi are suggested to constitute a robust population that is not congeneric with Magnaporthe salvinii, the type species of Magnaporthe. Second, genetic mechanisms involved in its parasitic specialization into host-specific subgroups and races are outlined. Implications of recent molecular data for resistance breeding are discussed.