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Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation for the development of fungicides for disease control. Mitophagy, a specific form of autophagy, is important for fungal virulence. The role of cardiolipin, mitochondrial signature phospholipid, in mitophagy and pathogenesis is largely unknown in plant pathogenic fungi. The functions of enzymes involved in cardiolipin biosynthesis and relevant inhibitors were assessed using a set of assays, including genetic deletion, plant infection, lipidomics, chemical‐protein interaction, chemical inhibition, and field trials. Our results showed that the cardiolipin biosynthesis‐related gene MoGEP4 of the rice blast fungus Magnaporthe oryzae regulates growth, conidiation, cardiolipin biosynthesis, and virulence. Mechanistically, MoGep4 regulated mitophagy and Mps1‐MAPK phosphorylation, which are required for virulence. Chemical alexidine dihydrochloride (AXD) inhibited the enzyme activity of MoGep4, cardiolipin biosynthesis and mitophagy. Importantly, AXD efficiently inhibited the growth of 10 plant pathogens and controlled rice blast and Fusarium head blight in the field. Our study demonstrated that MoGep4 regulates mitophagy, Mps1 phosphorylation and pathogenesis in M. oryzae. In addition, we found that the MoGep4 inhibitor, AXD, displays broad‐spectrum antifungal activity and is a promising candidate for fungicide development. Summary Statement: This study demonstrated that MoGep4 regulates mitophagy, Mps1 activation and pathogenesis in Magnaporthe oryzae. Additionally, we found that the MoGep4 inhibitor, alexidine dihydrochloride, displays broad‐spectrum antifungal activity and is effective in disease control in the field. [ABSTRACT FROM AUTHOR]

As with the majority of the hemibiotrophic fungal pathogens, the rice blast fungus Magnaporthe oryzae uses highly specialized infection structures called appressoria for plant penetration. Appressoria differentiated from germ tubes rely on enormous turgor pressure to directly penetrate the plant cell, in which process lipid metabolism plays a critical role. In this study, we characterized the MoPAH1 gene in M. oryzae, encoding a putative highly conserved phosphatidate phosphatase. The expression of MoPAH1 was up‐regulated during plant infection. The MoPah1 protein is expressed at all developmental and infection stages, and is localized to the cytoplasm. Disruption of MoPAH1 causes pleiotropic defects in vegetative growth, sporulation, and heat tolerance. The lipid profile is significantly altered in the Mopah1 mutant. Lipidomics assays showed that the level of phosphatidic acid (PA) was increased in the mutant, which had reduced levels of diacylglycerol and triacylglycerol. Using a PA biosensor, we showed that the increased level of PA in the Mopah1 mutant was primarily accumulated in the vacuole. The Mopah1 mutant was blocked in both conidiation and the formation of appressorium‐like structures at hyphal tips. It was nonpathogenic and failed to cause any blast lesions on rice and barley seedlings. RNA sequencing analysis revealed that MoPah1 regulates the expression of transcription factors critical for various developmental and infection‐related processes. The Mopah1 mutant was reduced in the expression and phosphorylation of Pmk1 MAP kinase and delayed in autophagy. Our study demonstrates that MoPah1 is necessary for lipid metabolism, fungal development, and pathogenicity in M. oryzae. [ABSTRACT FROM AUTHOR]