The Sphinganine C4-Hydroxylase MoSur2 Regulates Lipid Homeostasis and cell development in Magnaporthe oryzae

Magnaporthe oryzae causes rice blast disease and is an invasive threat to global rice crops production. Recent investigations revealed that sphingolipids play an important role in various cellular processes and give us molecular insights into roles of sphingolipid genes and their derivatives in plant pathogenic fungal disease reduction. However, the function of sphingolipids and their respective proteins in M. oryzae have not yet been understood in detail. To thoroughly understand the pathological role and characterization of sphingolipid proteins involved in virulence causing rice blast disease is demanded. In this research work, we carried out systematic analysis of another gene from sphingolipid pathway, which was found to be responsible for conidia development and pathogenicity. Knockout of MoSur2, a key sphinganine C4-Hydroxylase, resulted in significant disruption in the hyphal and conidia growth, and displayed a remarkable decrease in plasma membrane (PM) tension and virulence on the host plant. MoSur2 is also necessary for regulating cell wall intensity (CWI), and osmotic and oxidative stress Osm1-MAPK pathway. TORC2 analysis revealed that phosphorylation of Ypk1 regulates the PM stress and increases in feedback mechanism in the ∆ Mosur 2 mutant. By comprehensive lipidomics analysis, we found out significant alterations in major plasma membrane components resulting in increased level of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) alongside decreased level of ceramide (Cer) in the mutant. Moreover, MoSur2 is localized in the ER and its interaction with upstream proteins Spt2 and Tsc10 shows that the pathway is highly systematic. The inhibition effect of myriocin gives us insight that MoSur2 mutant could be a potential drug target. These findings improve our understanding of the characterization and functionalization of MoSur2 of the sphingolipid pathway and could be very useful for controlling rice blast disease through the development of specific drugs.