title: The FgHOG1 pathway regulates hyphal growth, stress responses, and plant infection in Fusarium graminearum.
abstract: Fusarium head blight (FHB) caused by Fusarium graminearum is a destructive disease of wheat and barley worldwide. In a previous study of systematic characterization of protein kinase genes in F. graminearum, mutants of three putative components of the osmoregulation MAP kinase pathway were found to have distinct colony morphology and hyphal growth defects on PDA plates. Because the osmoregulation pathway is not known to regulate aerial hyphal growth and branching, in this study we further characterized the functions of the FgHog1 pathway in growth, pathogenesis, and development. The Fghog1, Fgpbs2, and Fgssk2 mutants were all reduced in growth rate, aerial hyphal growth, and hyphal branching angle. These mutants were not only hypersensitive to osmotic stress but also had increased sensitivity to oxidative, cytoplasm membrane, and cell wall stresses. The activation of FgHog1 was blocked in the Fgpbs2 and Fgssk2 mutants, indicating the sequential activation of FgSsk2-FgPbs2-FgHog1 cascade. Interestingly, the FgHog1 MAPK pathway mutants appeared to be sensitive to certain compounds present in PDA. They were female sterile but retained male fertility. We also used the metabolomics profiling approach to identify compatible solutes that were accumulated in the wild type but not in the Fghog1 deletion mutant. Overall, our results indicate that the FgSsk2-FgPbs2-FgHog1 MAPK cascade is important for regulating hyphal growth, branching, plant infection, and hyperosmotic and general stress responses in F. graminearum.
authors.affiliation: NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Zheng
authors.forename: Shijie
authors.initials: S
authors.lastname: Zhang
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhou
authors.forename: Chenfang
authors.initials: C
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Xiang
authors.forename: Qian
authors.initials: Q
authors.lastname: Zheng
authors.forename: Jin-Rong
authors.initials: JR
authors.lastname: Xu
mesh_terms: D043383:Adenosylhomocysteinase / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015870:Gene Expression; D025301:Hyphae / Q000235:genetics / Q000254:growth & development; D020935:MAP Kinase Signaling System; D009154:Mutation; D009997:Osmotic Pressure; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D021381:Protein Transport; D015398:Signal Transduction; D013312:Stress, Physiological / Q000235:genetics; D013395:Sucrose / Q000378:metabolism; D013402:Sugar Alcohols / Q000378:metabolism; D014908:Triticum / Q000382:microbiology; D003313:Zea mays / Q000382:microbiology
chemical_list: D005656:Fungal Proteins; D013402:Sugar Alcohols; D013395:Sucrose; D043383:Adenosylhomocysteinase