The MAPKK kinase ChSte11 regulates sexual/asexual development, melanization, pathogenicity, and adaptation to oxidative stress in Cochliobolus heterostrophus
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All fungi use multiple mitogen-activated protein kinase (MAPK) cascades to respond to external signals to regulate specialized responses. In this study, we cloned and characterized a putative MAPKKK gene ChSte11, orthologous to yeast STE11, of Cochliobolus heterostrophus. ΔChste11 strains showed defects in conidiation, sexual development, melanization and the formation of appressoria. These mutants were significantly less virulent on corn plants than the wild type. Similar phenotypes were observed in mutants of Chk1-MAPK, a putative downstream protein kinase of ChSte11. These results suggested that ChSte11 regulates various morphological changes and pathogenicity via Chk1 MAPK. Both ΔChste11 and Δchk1 strains showed severe sensitivity to oxidative stress, hydrogen peroxide, and heavy metals, cupric or ferric cations. ΔBmhog1 strains, mutants of the HOG1-type MAPK, did not show sensitivity to these forms of stress. Our results strongly suggested that the Ste11-type MAPKKK regulates not only various morphological changes and pathogenicity, but also adaptations to stress via Chk1-type MAPK in filamentous fungi.
KeywordsSTE11 KSS1 FUS3 HOG1 P42/44
- Albertyn J, Hohmann S, Thevelein JM, Prior BA (1994) GPD1, which encodes glycerol-3-phosphate dehydrogenase, is essential for growth under osmotic stress in Saccharomyces cerevisiae and its expression is regulated by the high-osmolarity glycerol response pathway. Mol Cell Biol 14:4135–4144PubMedGoogle Scholar
- Carroll AM, Sweigard JA, Valent B (1994) Improved vectors for selecting resistance to hygromycin. Fungal Genet Newsl 41:22Google Scholar
- Lev S, Sharon A, Hadar R, Ma H, Horwitz BA (1999) A mitogen-activated protein kinase of the corn-leaf pathogen Cochliobolus heterostrophus is involved in conidiation, appressorium formation, and pathogenicity: diverse roles for mitogen-activated protein kinase homologs in foliar pathogens. Proc Natl Acad Sci USA 96:13542–13547PubMedCrossRefGoogle Scholar