Bioinformatic tools in the analysis of determinants of pathogenicity and ecology of entomopathogenic fungi used as microbial insecticides in crop protection

Abstract

Insect pathogenic fungi have a huge potential as microbial components of biopesticides which serve as benign components in plant protection. The infection cycle of these fungi is well known. Realising their potential and scope to improve their utility in phytomedicine, extensive work on the molecular biology of pathogenesis has been done in the past decade. Wet bench techniques like gene isolation, cloning and characterisation and gene knockout experiments to transcriptomics techniques like cDNA-AFLP, microarray, qPCR, cDNA, EST and SSH library construction, as well as whole genome sequencing and analysis of data with a suite of bioinformatic tools and pipelines integrated with several biological databases, were done to understand the process/processes involved at each stage of the infection cycle of the insect pathogenic fungi. These are in particular adherence of spores to the insect cuticle, factors that aid in coping with the physical stress conditions in the surrounding environment, formation of an infection peg, penetrance into the insect, factors that abet in overcoming insect defence systems and growth in the insect, production of toxic secondary metabolites that lead to insect death and surfacing out from the insect cadaver as well as sporulating to iterate the infection cycle on yet another insect. The picture that emerged is detailed in this chapter. The genes/proteins involved and the analyses that aided in their identification are described. Environmental genomics through multitag 454 pyrosequencing of rRNA sequence reads in deciphering the effect of the inundative application of an entomopathogenic fungus on the native soil fungal diversity is described. The chapter highlights the bioinformaticsbolstered investigation of the factors that influence the affectivity of insect pathogenic fungi as microbial biopesticides.