Environmental Microbiology (2019) 21, 3153-3171

Shuaishuai Huang, Nemat O. Keyhani, Xin Zhao and Yongjun Zhang (2019)
The Thm1 Zn(II)₂Cys₆ transcription factor contributes to heat, membrane integrity and virulence in the insect pathogenic fungus Beauveria bassiana
Environmental Microbiology 21 (8), 3153-3171
Abstract: The ability to withstand heat and cell wall stress is critical for successful infection of target hosts by many pathogenic fungi. We report on the characterization of BbThm1 (transcription factor for heat and membrane integrity), a Zn(II)₂Cys₆ (Gal4-like) family member, which regulates resistance to heat (32°C) and specific detergents in the insect pathogenic fungus, Beauveria bassiana. BbThm1 gene knock-out mutants showed severely impaired growth/resistance at 32°C and to SDS, but mild to moderate phenotypic responses to other stresses including oxidative, osmotic and cell-wall targeting compounds, or to various fungicides. Shifts in cell wall properties, adhesion and decreased viability were noted for the ΔBbThm1 mutant. Susceptibility to SDS but not heat could be rescued by exogenous ergosterol. Insect bioassays revealed decreased virulence of the ΔBbThm1 mutant against Galleria mellonella both topically and via intrahemocoel injection assays that correlated with impaired in insecta hyphal body formation and altered host immune prophenol oxidase (PO) activation. Transcriptomic analyses of the wild-type and ΔBbThm1 mutants revealed up-regulation of hydrolases but down-regulation of a wide range of basic metabolic processes. These data reveal fine tune aspects of the transcription factor network that regulates specific stress responses to contribute to the overall pathogenic process.
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Link to article at publishers website
Database assignments for author(s): Nemat O. Keyhani

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Beauveria bassiana (entomopathogen)