Two mating-type genes MAT1-1-1 and MAT1-1-2 with significant functions in conidiation, stress response, sexual development, and pathogenicity of rice false smut fungus Villosiclava virens

Rice false smut caused byVillosiclava virensis one of the destructive diseases on panicles of rice. Sexual development ofV. virens, controlled by mating-type locus, plays an important role in the prevalence of rice false smut and genetic diversity of the pathogen. However, how the mating-type genes mediate sexual development of theV. virensremains largely unknown. In this study, we characterized the two mating-type genes,MAT1-1-1andMAT1-1-2, inV. virens.MAT1-1-1knockout mutant showed defects in hyphal growth, conidia morphogenesis, sexual development, and increase in the tolerance to salt and osmotic stress. Targeted deletion ofMAT1-1-2not only impaired the sclerotia formation and pathogenicity ofV. virens, but also reduced the production of conidia. TheMAT1-1-2mutant showed increases in tolerance to salt and hydrogen peroxide stress, but decreases in tolerance to osmotic stress. Yeast two-hybrid assay showed that MAT1-1-1 interacted with MAT1-1-2, indicating that those proteins might form a complex to regulate sexual development. In addition, MAT1-1-1 localized in the nucleus, and MAT1-1-2 localized in the cytoplasm. Collectively, our results demonstrate thatMAT1-1-1andMAT1-1-2play important roles in the conidiation, stress response, sexual development, and pathogenicity ofV. virens, thus providing new insights into the function of mating-type gene.