Comparative genomic analysis revealed rapid differentiation in the pathogenicity-related gene repertoires between Pyricularia oryzae and Pyricularia penniseti isolated from a Pennisetum grass

Background A number of Pyricularia species are known to infect different grass species. In the case of Pyricularia oryzae (syn. Magnaporthe oryzae), distinct populations are known to be adapted to a wide variety of grass hosts, including rice, wheat and many other grasses. The genome sizes of Pyricularia species are typical for filamentous ascomycete fungi [~ 40 Mbp for P. oryzae, and ~ 45 Mbp for P. grisea]. Genome plasticity, mediated in part by deletions promoted by recombination between repetitive elements [Genome Res 26:1091-1100, 2016, Nat Rev Microbiol 10:417-430,2012] and transposable elements [Annu Rev Phytopathol 55:483-503,2017] contributes to host adaptation. Therefore, comparisons of genome structure of individual species will provide insight into the evolution of host specificity. However, except for the P. oryzae subgroup, little is known about the gene content or genome organization of other Pyricularia species, such as those infecting Pennisetum grasses.