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Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance
Published on: July 30, 2017
Use of Metarhizium anisopliae chitinase genes for genotyping and virulence characterization
Saliou Niassy1, Sevgan Subramanian, Sunday Ekesi
1International Centre of Insect Physiology and Ecology (icipe), Nairobi 00100, Kenya.
Abstract:
Virulence is the primary factor used for selection of entomopathogenic fungi (EPF) for development as biopesticides. To understand the genetic mechanisms underlying differences in virulence of fungal isolates on various arthropod pests, we compared the chitinase genes, chi2 and chi4, of 8 isolates of Metarhizium anisopliae. The clustering of the isolates showed various groups depending on their virulence. However, the analysis of their chitinase DNA sequences chi2 and chi4 did not reveal major divergences. Although their protein translates have been implicated in fungal virulence, the predicted protein structure of chi2 was identical for all isolates. Despite the critical role of chitin digestion in fungal infection, we conclude that chi2 and chi4 genes cannot serve as molecular markers to characterize observed variations in virulence among M. anisopliae isolates as previously suggested. Nevertheless, processes controlling the efficient upregulation of chitinase expression might be responsible for different virulence characteristics. Further studies using comparative "in vitro" chitin digestion techniques would be more appropriate to compare the quality and the quantity of chitinase production between fungal isolates.
Insights
Chitinase genes chi2 and chi4 in Metarhizium anisopliae do not explain virulence differences in entomopathogenic fungi. Upregulation of chitinase expression likely influences virulence, not genetic sequence variations.
Area of Science:
- Mycology
- Molecular Biology
- Biopesticide Development
Background:
- Entomopathogenic fungi (EPF) are crucial for biopesticide development, with virulence being a key selection factor.
- Understanding the genetic basis of virulence differences in EPF isolates is essential for optimizing biopesticide efficacy.
Purpose of the Study:
- To investigate the role of chitinase genes (chi2 and chi4) in the varying virulence of Metarhizium anisopliae isolates against arthropod pests.
- To determine if DNA sequence variations in chi2 and chi4 can serve as molecular markers for M. anisopliae virulence.
Main Methods:
- Comparative analysis of chi2 and chi4 gene DNA sequences from eight M. anisopliae isolates with differing virulence profiles.
- Analysis of predicted protein structures for chi2 and chi4.
Main Results:
- Clustering of M. anisopliae isolates revealed distinct groups based on virulence.
- No significant DNA sequence divergences were found in the chi2 and chi4 genes among the isolates.
- The predicted protein structure of chi2 was identical across all isolates, despite its known role in fungal virulence.
Conclusions:
- The chi2 and chi4 genes are not suitable molecular markers for differentiating virulence variations in M. anisopliae isolates.
- Differences in virulence are more likely attributed to regulatory mechanisms controlling chitinase gene expression levels.
- Further research should focus on in vitro chitinase production assays to assess quantitative and qualitative differences.
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