State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.
Department of Biology, Kaiserslautern University, 67663, Kaiserslautern, Germany.
New Phytol. 2019 Jul;223(1):412-429. doi: 10.1111/nph.15748. Epub 2019 Mar 20.
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 target of rapamycin (TOR) 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. TOR in Fusarium graminearum (FgTOR) inhibition by rapamycin induces LD biogenesis through the FgPpg1/Sit4 signaling branch. FgPpg1 promotes phosphorylation 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. The results of this study provide novel insights into the regulatory mechanism and biological functions of the LDs in the devastating pathogenic fungus F. graminearum.
脂滴（LDs）普遍控制真核细胞中的脂质代谢。然而，在病原真菌中，LD 的生物发生调控及其生物学功能在很大程度上仍是未知的。雷帕霉素处理导致禾谷镰刀菌中 LD 的生物发生显著增加。通过结合遗传、细胞学和表型策略，深入研究了雷帕霉素靶蛋白（TOR）途径在调控 LD 生物发生和 LD 在禾谷镰刀菌毒力中的功能的分子机制。雷帕霉素抑制禾谷镰刀菌中的 TOR（FgTOR）通过 FgPpg1/Sit4 信号分支诱导 LD 生物发生。FgPpg1 促进蛋白激酶 FgCak1 磷酸化蛋白磷酸酶 FgNem1。磷酸化的 FgNem1 去磷酸化磷酸二酯酶 FgPah1。去磷酸化的 FgPah1 具有活性并刺激 LD 生物发生。此外，FgNem1/Spo7 或 FgPah1 的缺失导致营养生长、有性生殖和毒力严重缺陷。这项研究的结果为破坏性病原真菌禾谷镰刀菌中 LD 的调控机制和生物学功能提供了新的见解。
