The fungal MAP kinase Pmk1 controls intracellular spread of rice blast fungus in rice cells (Science)

Magnaporthe oryzae is a devastating fungal pathogen that routinely threatens rice crop yields. Rice blast infection occurs when fungal hyphae penetrate into and proliferate within living plant cells, moving intracellulary from cell-to-cell through plasmodesmatal junctions. In a recent article published by Sakulkoo et al. (Science), chemical genetics revealed that a single MAP Kinase, Pmk1, is essential for the cell-to-cell spread of fungal hyphae. The authors demonstrated that Pmk1 inhibition rendered fungal hyphae unable to penetrate through plasmodesmata, effectively trapping the pathogen within plant cells. This inhibition was associated with an inability to induce effector gene expression that is normally required to suppress host immunity. Together, the data support a critical role for Pmk1 in regulating the cell-to-cell spread of fungal hyphae through plant cell-cell junctions. (Summary by Philip Carella) Science 10.1126/science.aaq0892