Lipid droplet biogenesis regulated by the FgNem1/Spo7-FgPah1 phosphatase cascade plays critical roles in fungal development and virulence in Fusarium graminearum.

●Lipid droplets (LDs) control lipid metabolism in eukaryotic cells in general. However, the biogenesis regulation and biological functions of LDs are largely unknown in pathogenic fungi. ● Rapamycin treatment results in a significant increase of LD biogenesis in Fusarium graminearum. Molecular mechanisms of the TOR (target of rapamycin) pathway in regulating LD biogenesis and the functions of LD in virulence of F. graminearum were investigated in depth by combining genetic, cytological and phenotypic strategies. ●FgTOR inhibition by rapamycin induces LD biogenesis through the FgPpg1/Sit4 signaling branch. FgPpg1 promotes the phosphorylation level of protein phosphatase FgNem1 by the protein kinase FgCak1. The phosphorylated FgNem1 dephosphorylates the phosphatidate phosphatase FgPah1. Dephosphorylated FgPah1 is active and stimulates LD biogenesis. Moreover, deletion of FgNem1/Spo7 or FgPah1 leads to serious defects in vegetative growth, sexual development and virulence. ● Results of this study provide a novel insight into the regulatory mechanism and biological functions of the LDs in the devastating pathogenic pathogen F. graminearum. This article is protected by copyright. All rights reserved.