Mnh6, a nonhistone protein, is required for fungal development and pathogenicity of Magnaporthe grisea

Mnh6, a nonhistone protein containing an HMG1 box, was isolated from the rice blast fungus, Magnaporthe grisea. In the current study, we utilized an MNH6-deletion mutant to investigate the role of Mnh6 in the disease cycle of M. grisea. The Deltamnh6 mutant exhibited pleiotropic effects on fungal morphogenesis, including reduction in mycelial growth, conidiation, appressorium development, plant penetration, and infectious growth in host cells. Furthermore, Deltamnh6 mutant had greatly reduced pathogenicity on barley and rice compared to the wild-type. The reintroduction of an intact copy of MNH6 into the Deltamnh6 mutant restored morphological features and pathogenicity, suggesting that Mnh6 is required for fungal development, effective pathogenicity, and completion of the disease cycle of M. grisea.