, a Hybrid Histidine Kinase Gene, Is Essential for the Sexual Development and Virulence of .

Hybrid histidine kinase is part of a two-component system that is required for various stress responses and pathogenesis of pathogenic fungi. The gene in human pathogen encodes a hybrid histidine kinase and is important for pathogenesis. In this study, we identified a homolog, , in the maize pathogen by bioinformatics analysis. To explore the role of in the survival of under environmental stresses and its pathogenesis, mutants were constructed by allelic exchange. The growth of mutants was significantly impaired when they were cultured under hyperosmotic stress. The mutants exhibited increased resistance to antifungal agent fludioxonil. In particular, the mutants were unable to produce cytokinesis or conjugation tubes, and to develop fuzzy filaments, resulting in impaired mating between compatible strains. The expression levels of , and , which are involved in the pheromone pathway, were significantly decreased in the mutants. In inoculation tests to the host plant, the mutants showed significantly reduced ability in the production of anthocyanin pigments and tumor development on maize leaves. Overall, the combined results indicated that plays important roles in the survival under hyperosmotic stress, and contributes to cytokinesis, sexual development, and virulence of by regulating the expression of the genes involved in the pheromone pathway.