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A Group III histidine kinase (mhk1) upstream of high‐osmolarity glycerol pathway regulates sporulation, multi‐stress tolerance and virulence of Metarhizium robertsii , a fungal entomopathogen
Author(s) -
Zhou Gang,
Wang Jie,
Qiu Lei,
Feng MingGuang
Publication year - 2012
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2011.02643.x
Subject(s) - biology , virulence , microbiology and biotechnology , osmotic shock , spore , metarhizium , histidine kinase , histidine , gene , metarhizium anisopliae , botany , conidium , biochemistry , enzyme
Summary The role of Metarhizium robertsii Group III histidine kinase (mhk1) in regulating various phenotypes of the fungal entomopathogen and the transcripts of 25 downstream genes likely associated with the phenotypes were probed by constructing Δ mhk1 and Δ mhk1/mhk1 mutants. All examined Δ mhk1 phenotypes except unchanged sensitivity to fungicide (dimethachlon) differed significantly from those of wild type and Δ mhk1/mhk1 , which were similar to each other. Significant phenotypic changes in Δ mhk1 included increased conidial yields on two media, increased tolerance to H 2 O 2 , decreased tolerance to menadione, increased tolerance to hyperosmolarity, increased conidial thermotolerance, decreased conidial UV‐B resistance and reduced virulence to Tenebrio molitor larvae. The mhk1 disruption elevated the transcripts of nine genes, including two associated with conidiation ( flbC and hymA ) and three encoding catalases but decreased seven other gene transcripts, including three for superoxide dismultases, under normal conditions. The high‐osmolarity glycerol pathway MAPK phosphorylation level in Δ mhk1 culture was increased 1.0‐ to 1.8‐fold by KCl, sucrose and menadione stresses but reduced drastically by H 2 O 2 or heat (40°C) stress, accompanied with different transcript patterns of all examined genes under the stresses. Our results confirmed the crucial role of mhk1 in regulating the expression of the downstream genes and associated phenotypes important for the fungal biocontrol potential.