TITLE

The Ste12-like transcription factor MaSte12 is involved in pathogenicity by regulating the appressorium formation in the entomopathogenic fungus, Metarhizium acridum

AUTHOR(S)
Wei, Qinglv; Du, Yanru; Jin, Kai; Xia, Yuxian
PUB. DATE
December 2017
SOURCE
Applied Microbiology & Biotechnology;Dec2017, Vol. 101 Issue 23/24, p8571
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Homeodomain transcription factor Ste12 is a key target activated by the pathogenic mitogen-activated-protein kinase pathway, and the activated Ste12p protein regulates downstream gene expression levels to modulate phenotypes. However, the functions of Ste12-like genes in entomopathogenic fungi remain poorly understood and little is known about the downstream genes regulated by Ste12. In this study, we characterized the functions of a Ste12 orthologue in Metarhizium acridum, MaSte12, and identified its downstream target genes. The deletion mutant (Δ MaSte12) is defective in conidial germination but not in hyphal growth, conidiation, or stress tolerance. Bioassays showed that Δ MaSte12 had a dramatically decreased virulence in topical inoculations, but no significant difference was found in intrahemolymph injections when the penetration process was bypassed. The mature appressorium formation rate of Δ MaSte12 was less than 10% on locust wings, with the majority hyphae forming appressorium-like, curved but no swollen structures. Digital gene expression profiling revealed that some genes involved in cell wall synthesis and remodeling, appressorium development, and insect cuticle penetration were downregulated in Δ MaSte12. Thus, MaSte12 has critical roles in the pathogenicity of the entomopathogenic fungus M. acridum, and our study provides some explanations for the impairment of fungal virulence in Δ MaSte12. In addition, virulence is very important for fungal biocontrol agents to control insect pests effectively. This study demonstrated that MaSte12 is involved in fungal virulence but not conidial yield or fungal stress tolerance in M. acridum. Thus, MaSte12 and its downstream genes may be candidates for enhancing fungal virulence to improve mycoinsecticides.
ACCESSION #
126307867

 

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