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Published on: July 30, 2017
Proteomic Analysis of a Hypervirulent Mutant of the Insect-Pathogenic Fungus Metarhizium anisopliae Reveals Changes
Wenyou Huang1, Peiquan Huang1, Dan Yü1
1South China Agricultural Universitygrid.20561.30, College of Plant Protection, Key Laboratory of Bio-Pesticide Creation and Application of Guangdong Province, Guangzhou, China.
Abstract:
Metarhizium anisopliae is a commercialized entomopathogenic fungus widely used for the control of insect pests. Significant efforts have been expended to screen and/or select for isolates that display increased virulence toward target insect hosts. UV-induced mutagenesis has resulted in the isolation of a number of hypervirulent M. anisopliae mutants; however, the underlying mechanisms that have led to the desired phenotype have yet to be characterized. Here, we performed a comparative proteomic analysis of an M. anisopliae UV-induced hypervirulent mutant (MaUV-HV) and its wild-type parent using tandem mass tag (TMT)-based quantitative proteomics. A total of 842 differentially abundant proteins were identified, with 360 being more abundant in the hypervirulent mutant and 482 in the wild-type parent. In terms of differential abundance, the critical pathways affected included those involved in secondary metabolite production, virulence, and stress response. In addition, a number of genes involved in terpenoid biosynthesis pathways were identified as significantly mutated in the MaUV-HV strain. In particular, mutations in the farnesyl pyrophosphate synthase (FPPS1) and geranylgeranyl diphosphate synthase (GGPPS5) genes were seen. The effects of the FPPS1 mutation were confirmed via the construction and characterization of a targeted gene knockout strain (ΔMaFPPS1). The overall effects of the mutations were increased resistance to UV stress, faster growth, and increased virulence. These results provide mechanistic insights and new avenues for modulating fungal virulence in efforts to increase the biological control potential of insect-pathogenic fungi. IMPORTANCE The mechanisms that underlie and contribute to microbial (fungal) virulence are known to be varied; however, the identification of contributing pathways beyond known virulence factors remains difficult. Using TMT-based proteomic analyses, changes in the proteomes of an M. anisopliae hypervirulent mutant and its wild-type parent were determined. These data revealed alterations in pathogenicity, stress, and growth/developmental pathways, as well as pathways not previously known to affect virulence. These include terpenoid pathways that can be manipulated to increase the efficacy of fungal insect biological control agents for increased sustainable pest control.
Insights
Researchers identified key molecular changes in a hypervirulent Metarhizium anisopliae mutant. These findings reveal new pathways, like terpenoid biosynthesis, that enhance fungal virulence for improved insect biological control.
Area of Science:
- Agricultural Science
- Mycology
- Molecular Biology
Background:
- Metarhizium anisopliae is a key entomopathogenic fungus used in biological pest control.
- Enhancing fungal virulence is crucial for improving the efficacy of biocontrol agents.
- Mechanisms underlying hypervirulence in M. anisopliae mutants remain largely uncharacterized.
Purpose of the Study:
- To conduct a comparative proteomic analysis of a UV-induced hypervirulent M. anisopliae mutant (MaUV-HV) and its wild-type parent.
- To identify the molecular mechanisms and pathways contributing to the hypervirulent phenotype.
- To explore novel targets for enhancing fungal virulence and biocontrol potential.
Main Methods:
- Tandem mass tag (TMT)-based quantitative proteomics was employed for comparative analysis.
- Proteomic data was analyzed to identify differentially abundant proteins between the mutant and wild-type strains.
- Gene knockout studies were performed to validate the role of specific genes, such as FPPS1.
Main Results:
- 842 differentially abundant proteins were identified, with significant changes in pathways related to secondary metabolite production, virulence, and stress response.
- Mutations were identified in terpenoid biosynthesis genes, including farnesyl pyrophosphate synthase (FPPS1) and geranylgeranyl diphosphate synthase (GGPPS5).
- A targeted knockout of MaFPPS1 resulted in increased UV stress resistance, faster growth, and enhanced virulence.
Conclusions:
- Proteomic analysis revealed that alterations in terpenoid biosynthesis pathways contribute significantly to M. anisopliae hypervirulence.
- The study provides mechanistic insights into fungal virulence and identifies potential targets for genetic manipulation.
- Modulating these pathways offers a promising strategy for developing more effective fungal-based insect biological control agents for sustainable agriculture.
