Analysis of differential gene expression in the generalist entomopathogenic fungus Beauveria bassiana (Bals.) Vuillemin grown on different insect cuticular extracts and synthetic medium through cDNA-AFLPs.

The entomopathogen Beauveria bassiana has an extremely diverse insect host range in addition to a saprophytic phase. The molecular basis for this plasticity was investigated by a comparative analysis of gene expression patterns through cDNA-AFLPs of a B. bassiana isolate grown on cuticular extracts of insects of diverse orders as well as synthetic medium. For some of the fragments, expression patterns were verified by Q-RT-PCR. Among the differentially expressed genes two proteases were identified, which are known to be directly involved in the process of pathogenesis in entomopathogenic fungi. However, the majority of the transcript derived fragments identified have a rather indirect function in fungal pathogenesis, as they are involved in the regulation of gene expression, signal transduction, cytoskeleton formation or secretion. In general, the gene expression profile of the fungal isolate on cuticular extracts of diverse insects was pretty similar. This sheds light on the putative generalist nature of B. bassiana with its ability to penetrate many different insect cuticles possibly due to a rather stereotype gene expression program.