Differentiating the pathogenicity of millet blast races and establishing a stable genetic transformation system

Abstract

<p indent="0mm">The fungal pathogen <italic>Magnaporthe</italic> causes blast disease and destroys millet, rice, and wheat crops worldwide, which threatens global food production. Blast disease has spread in the main millet-producing area of China and is pathogenically differentiated in different ecological regions. Therefore, a study on the pathogenicity of millet blast races, the resistance spectrum of millet cultivars in the adult stage, and establishing a genetic transformation system for the blast fungus is of great significance for distributing local millet resources, controlling blast, and improving the yield and quality of millet. Herein, we collected blast races from six regions nationwide, isolated them from single spores, and successfully induced extensive conidial spores in tomato plants. Furthermore, we conducted artificial <italic>in-vitro</italic> inoculation experiments with different millet varieties to evaluate their resistance spectra at the seedling stage and lay a solid foundation to isolate disease-resistant genes. The results showed that the pathogenicity of the strains to different varieties was divergent; however, the virulence of the races from Hainan Province was significantly stronger than that from other regions. Thus, the HN-1 strain with the highest infectivity was inoculated into 17 different adult-stage cultivars in the field. Consequently, four cultivars with adult-plant resistance were screened out. We established a stable genetic transformation system in the HN-1 background to provide a technical foundation for future studies on millet blast virulent proteins.