Use ofMetarhizium anisopliaeChitinase Genes for Genotyping and Virulence Characterization

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.

Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies

“…Successful field applications have been demonstrated in various countries to control A. aegypti [144], A. albopictus [145] and malaria mosquito vectors [146]. A couple of these fungi such as Metarhizium anisopliae ICIPE 7 and Metarhizium anisopliae ICIPE 20 have been isolated from Kenya and tested in the control of various insect pests [147,148]. Their success, especially in tick control programs, has seen their commercialization and official product registration.…”

Biopesticide Research and Product Development in Africa for Sustainable Agriculture and Food Security – Experiences From the International Centre of Insect Physiology and Ecology (icipe)

“…Several factors beyond the efficacy of entomopathogens determine success toward their development into biopesticide products, including environmental suitability, and amenability for mass production and horizontal transmission, among others. Current R4D efforts are already aimed at using genotyping to improve biopesticide development, such as studies toward M. anisopliae chitinase genes and virulence factors (Niassy et al, 2013). We found that the chitinase genes chi2 and chi4 of eight M. anisopliae strains (ICIPE 7,20,30,41,62,63, 69 and 78) did not reveal major divergences as the predicted protein structure of chi2 was identical for all the selected strains.…”

Susceptibility of the Western Honey BeeApis melliferaand the African Stingless BeeMeliponula ferruginea(Hymenoptera: Apidae) to the Entomopathogenic FungiMetarhizium anisopliaeandBeauveria bassiana

“…Reportedly, the generalist entomopathogenic fungi commonly possess a couple of virulence genes such as subtilisin-like Pr1 genes ( Gao et al 2020 ). In particular, ICIPE 7, ICIPE 20, and ICIPE 69 are highly pathogenic to diverse pest groups, which could be related to the possession of chitinase chi2 and chi4 genes, and additional genes for toxin production and conidiation ( Niassy et al 2013 ).…”