title: PsMPK7, a stress-associated mitogen-activated protein kinase (MAPK) in Phytophthora sojae, is required for stress tolerance, reactive oxygenated species detoxification, cyst germination, sexual reproduction and infection of soybean.
abstract: The sensing of stress signals and their transduction into appropriate responses are crucial for the adaptation, survival and infection of phytopathogenic fungi and oomycetes. Amongst evolutionarily conserved pathways, mitogen-activated protein kinase (MAPK) cascades function as key signal transducers that use phosphorylation to convey information. In this study, we identified a gene, designated PsMPK7, one of 14 predicted genes encoding MAPKs in Phytophthora sojae. PsMPK7 was highly transcribed in each tested stage, but was up-regulated in the zoospore, cyst and cyst germination stages. Silencing of PsMPK7 affected the growth of germinated cysts, oospore production and the pathogenicity of soybean. PsMPK7 transcription was induced by stresses from sorbitol, NaCl and hydrogen peroxide. Transformants in which PsMPK7 expression was silenced (PsMPK7-silenced) were significantly more sensitive to osmotic and oxidative stress. Aniline blue and diaminobenzidine staining revealed that the silenced lines did not suppress the host reactive oxygen species (ROS) burst, indicating that either the inoculated plants activated stronger defence responses to the transformants and/or the PsMPK7-silenced transformants failed to overcome plant defences. In addition, extracellular secretion of laccase decreased in the silenced lines. Overall, our results indicate that the PsMPK7 gene encodes a stress-associated MAPK in P. sojae that is important not only for responses to various stresses, but also for ROS detoxification, cyst germination, sexual oospore production and infection of soybean.
authors.affiliation: Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.forename: Mingna
authors.initials: M
authors.lastname: Cao
authors.forename: Wenwu
authors.initials: W
authors.lastname: Ye
authors.forename: Haiyang
authors.initials: H
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Kong
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zheng
authors.forename: Yuanchao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D005110:Extracellular Space / Q000201:enzymology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D042845:Laccase / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D025282:Mycelium / Q000187:drug effects / Q000254:growth & development; D009995:Osmosis / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D010838:Phytophthora / Q000187:drug effects / Q000201:enzymology* / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012098:Reproduction / Q000187:drug effects; D036226:Seedlings / Q000382:microbiology; D012965:Sodium Chloride / Q000494:pharmacology; D013025:Glycine max / Q000187:drug effects / Q000235:genetics / Q000382:microbiology*; D013170:Spores / Q000187:drug effects / Q000254:growth & development*; D013312:Stress, Physiological / Q000187:drug effects; D014170:Transformation, Genetic / Q000187:drug effects
chemical_list: D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D042845:Laccase; D020928:Mitogen-Activated Protein Kinases
keywords: MAPK; Phytophthora sojae; cyst germination; oospore production; pathogenicity; stress-activated protein kinase