title: AbSte7, a MAPKK Gene of Alternaria brassicicola, is Involved in Conidiation, Salt/Oxidative Stress, and Pathogenicity.
abstract: Alternaria brassicicola (Schwein.) invades Brassicaceae and causes black spot disease, significantly lowering productivity. Mitogen-activated protein kinases (MAPKs) and their upstream kinases, including MAPK kinases (MAPKKs) and MAPKK kinases (MAPKKK), comprise one of the most important signaling pathways determining the pathogenicity of diverse plant pathogens. The AbSte7 gene in the genome of A. brassicicola was predicted to be a homolog of yeast Ste7, a MAPKK; therefore, the function was characterized by generating null mutant strains with a gene replacement method. AbSte7 replacement mutants (RMs) had a slower growth rate and altered colony morphology compared with the wild-type strain. Disruption of the AbSte7 gene resulted in defects in conidiation and melanin accumulation. AbSte7 was also involved in the resistance pathways in salt and oxidative stress, working to negatively regulate salt tolerance and positively regulate oxidative stress. Pathogenicity assays revealed that AbSte7 RMs could not infect intact cabbage leaves, but only formed very small lesions in wounded leaves, whereas typical lesions appeared on both intact and wounded leaves inoculated with the wild-type strain. As the first studied MAPKK in A. brassicicola, these data strongly suggest that the AbSte7 gene is an essential element for the growth, development, and pathogenicity of A. brassicicola.
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Houjuan
authors.initials: H
authors.lastname: Xu
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Cui
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Weiyang
authors.initials: W
authors.lastname: Liu
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Biotechnology, Yeungnam University, Gyeongsan 38541, Republic of Korea.
authors.forename: Md Nurul
authors.initials: MN
authors.lastname: Islam
authors.affiliation: Department of Biotechnology, Yeungnam University, Gyeongsan 38541, Republic of Korea.
authors.forename: Kwang-Hyun
authors.initials: KH
authors.lastname: Baek
authors.affiliation: College of Plant Protection, Shandong Agricultural University, Tai'an 271018, P.R. China.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000528:Alternaria / Q000145:classification / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D018390:Gene Targeting; D008543:Melanins / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics* / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D055049:Salt Tolerance / Q000235:genetics*; D013172:Spores, Fungal / Q000235:genetics*; D014774:Virulence / Q000235:genetics
chemical_list: D008543:Melanins; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: Alternaria brassicicola; conidiation; mitogen-activated protein kinase kinase (MAPKK); oxidative stress; pathogenicity; salt stress