Mitogen-activated protein kinase hog1 in the entomopathogenic fungus Beauveria bassiana regulates environmental stress responses and virulence to insects.
Beauveria bassiana is an economically important insect-pathogenic fungus which is widely used as a biocontrol agent to control a variety of insect pests. However, its insecticide efficacy in the field is often influenced by adverse environmental factors. Thus, understanding the genetic regulatory processes involved in the response to environmental stress would facilitate engineering and production of a more efficient biocontrol agent. Here, a mitogen-activated protein kinase (MAPK)-encoding gene, Bbhog1, was isolated from B. bassiana and shown to encode a functional homolog of yeast HIGH-OSMOLARITY GLYCEROL 1 (HOG1). A Bbhog1 null mutation was generated in B. bassiana by targeted gene replacement, and the resulting mutants were more sensitive to hyperosmotic stress, high temperature, and oxidative stress than the wild-type controls. These results demonstrate the conserved function of HOG1 MAPKs in the regulation of abiotic stress responses. Interestingly, DeltaBbhog1 mutants exhibited greatly reduced pathogenicity, most likely due to a decrease in spore viability, a reduced ability to attach to insect cuticle, and a reduction in appressorium formation. The transcript levels of two hydrophobin-encoding genes, hyd1 and hyd2, were dramatically decreased in a DeltaBbhog1 mutant, suggesting that Bbhog1 may regulate the expression of the gene associated with hydrophobicity or adherence.
Zhang
Yongjun
Y
Biotechnology Research Center, Southwest University, Chongqing, People's Republic of China.
Zhao
Jianhua
J
Fang
Weiguo
W
Zhang
Jianqing
J
Luo
Zhibing
Z
Zhang
Mi
M
Fan
Yanhua
Y
Pei
Yan
Y
D000818:Animals; D001042:Aphids / Q000382:microbiology*; D052982:Beauveria / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D002448:Cell Adhesion; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D055786:Gene Knockout Techniques; D006358:Hot Temperature; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D018384:Oxidative Stress; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological; D014774:Virulence
D004271:DNA, Fungal; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases