title: The mitogen-activated protein kinase gene, VdHog1, regulates osmotic stress response, microsclerotia formation and virulence in Verticillium dahliae.
abstract: The fungus Verticillium dahliae has gained worldwide notoriety as a destructive plant pathogen, causing vascular wilt diseases on diverse plant species. V. dahliae produces melanized resting bodies, known as microsclerotia, which can survive for 15 years in the soil, and are thus critically important in its disease cycle. However, the molecular mechanisms that underpin microsclerotia formation, survival, and germination remain poorly understood. In this study, we observed that deletion of VdHog1 (ΔVdHog1), encoding a homolog of a high-osmolarity glycerol (HOG) response mitogen-activated protein kinase, displayed decreased numbers of melanized microsclerotia in culture, heightened sensitivity to hyperosmotic stress, and increased resistance to the fungicide fludioxonil. Through RNA-Seq analysis, we identified 221 genes differentially expressed in the ΔVdHog1 strain. Interestingly, the expression levels of genes involved in melanin biosynthesis, as well as the hydrophobin gene VDH1, involved in the early stage of microsclerotia formation, were significantly decreased in the ΔVdHog1 strains relative to the wild-type expression levels. The ΔVdHog1 strains exhibited decreased virulence relative to the wild type strain on smoke tree seedlings. These results indicate that VdHog1 regulates hyperosmotic stress responses in V. dahliae, and establishes the Hog1-mediated pathway as a target to further probe the up- and downstream processes that regulate asexual development in this fungus.
authors.affiliation: The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
authors.forename: Longyan
authors.initials: L
authors.lastname: Tian
authors.affiliation: The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
authors.forename: Dianguang
authors.initials: D
authors.lastname: Xiong
authors.affiliation: United States Department of Agriculture-Agricultural Research Service, Salinas, CA, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Klosterman
authors.affiliation: The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
authors.forename: Shuxiao
authors.initials: S
authors.lastname: Xiao
authors.affiliation: The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China. Electronic address: chengmt@bjfu.edu.cn.
authors.forename: Chengming
authors.initials: C
authors.lastname: Tian
mesh_terms: D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D008543:Melanins / Q000096:biosynthesis / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D064587:Osmoregulation; D010802:Phylogeny; D012100:Reproduction, Asexual / Q000235:genetics; D016415:Sequence Alignment; D017384:Sequence Deletion; D020172:Verticillium / Q000235:genetics* / Q000254:growth & development; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D008543:Melanins; D020928:Mitogen-Activated Protein Kinases
keywords: Hog1-type MAPK; Microsclerotia formation; Osmotic stress; Verticillium dahliae; Virulence