MoErv14 mediates the intracellular transport of cell membrane receptors to govern the appressorial formation and pathogenicity of Magnaporthe oryzae

Magnaporthe oryzae causes rice blasts posing serious threats to food security worldwide. During infection, M. oryzae utilizes several transmembrane receptor proteins that sense cell surface cues to induce highly specialized infectious structures called appressoria. However, little is known about the mechanisms of intracellular receptor tracking and their function. Here, we described that disrupting the coat protein complex II (COPII) cargo protein MoErv14 severely affects appressorium formation and pathogenicity as the Delta Moerv14 mutant is defective not only in cAMP production but also in the phosphorylation of the mitogen-activated protein kinase (MAPK) MoPmk1. Studies also showed that either externally supplementing cAMP or maintaining MoPmk1 phosphorylation suppresses the observed defects in the Delta Moerv14 strain. Importantly, MoErv14 is found to regulate the transport of MoPth11, a membrane receptor functioning upstream of G-protein/cAMP signaling, and MoWish and MoSho1 function upstream of the Pmk1-MAPK pathway. In summary, our studies elucidate the mechanism by which the COPII protein MoErv14 plays an important function in regulating the transport of receptors involved in the appressorium formation and virulence of the blast fungus. Author summaryDuring the pathogenic interaction with rice, Magnaporthe oryzae senses cell surface cues and forms a highly specialized infectious structure called an appressorium that initiates the infection. Studies have shown several transmembrane proteins essential for the perception of rice host cues. However, little is known about how these transmembrane proteins are trafficked intracellularly to impact appressorium formation and pathogenicity. In this study, we found MoErv14 is important in the growth and pathogenicity of the blast fungus, and MoErv14 regulates the transport of several membrane sensors, including MoPth11, MoWish, and MoSho1, that function upstream of either G-protein/cAMP signaling or the Pmk1-MAPK pathway. Importantly, we revealed that MoErv14 mediates the transport of these receptor proteins to promote the appressorium formation and pathogenicity of M. oryzae.