Effects of irradiation treatments on genetic variation and damage repair in the rice blast fungus Magnaporthe oryzae

Harsh environments have fatal impacts on growing fungi. Research on fungal variation and damage repair in harsh environments is important to reveal how fungi can maintain their strong survival ability. In this study, using a gradient range of absorbed doses, we analyzed the colony morphology, growth rate and spore production of Magnaporthe oryzae isolates after irradiation by γ-rays released from a 60 Co radioactive source, and then the relative pathogenicity of the treated isolates was analyzed. Our results showed that absorbed doses of < 1 × 10 3 mGy had little effect on the growth of M. oryzae isolates. We found that ionizing radiation at different doses could reduce sporulation, but there was no significant difference in spore production when the absorbed dose was < 2.2 × 10 6 mGy. The subcultured isolates underwent self-repair, and the growth rate was greatly restored in the absence of radiation. At an absorbed dose of 1 × 10 7 mGy, all of the tested isolates were inactivated. For the same radiation degree, the effect of a low dose over a long time to rice blast fungus was stronger than that of a strong dose over a short time. The goal of this study was to reveal the influence of radiation on rice blast fungus and to reveal the genetic variation and recovery ability of M. oryzae under harsh environments. The results demonstrated the strong adaptation and survival ability of M. oryzae .