Pmk1 as a target for both protective and curative treatments against pathogenic fungi

Rice production is threatened by blast disease caused by Magnaporthe oryzae. Application of fungicides remain one of the main controlling strategies. Due to the emergence of resistant strains, developing fungicides with novel mechanisms has become necessary. The Pmk1 kinase of M. oryzae is essential for fungal virulence, particularly in appressoria formation and invasive hyphae expansion within the host. Herein, we demonstrate that Pmk1 can serve as a potential target for fungicide development, and present the critical sites of Pmk1 for inhibitor design. Through high-throughput screening, we obtained the compound A59, which interacts with Pmk1 and inhibits its activity. In vivo assays showed that A59 suppresses appressoria development and invasive hyphae expansion of M. oryzae in the hosts, manifesting both protective and therapeutic effects. With an integration of computational and experimental validation, we demonstrated that A59 binds to the catalytic pocket of Pmk1 and identified the critical sites of Pmk1 for inhibitor interaction. These findings were further supported by the evaluation of chiral isomers of A59. This study presents Pmk1 as a novel fungal MAPK target for developing fungicides with protective and therapeutic effects, and identifies Pmk1 critical residues for inhibitor interactions, providing a foundation for rational design of Pmk1-targeted fungicides.