Identification and characterization of the glycoside hydrolase family 18 genes from the entomopathogenic fungus genome.

Fungal chitinases play essential roles in chitin degradation, cell wall remodeling, chitin recycling, nutrition acquisition, autolysis, and virulence. In this study, 18 genes of the glycoside hydrolase 18 (GH18) family were identified in the genome. Seventeen of the genes belonged to chitinases and one was an endo-β--acetylglucosaminidase (ENGase). According to phylogenetic analysis, the 17 chitinases were designated as subgroups A (7 chitinases), B (7), and C (3). The exon-intron organizations of these genes were analyzed. The conserved regions DxxDxDxE and S/AxGG and the domains CBM1, CBM18, and CBM50 were detected in chitinases and ENGase. The results of analysis of expression patterns showed that genes , , , and had high transcript levels in the different growth conditions or developmental stages. Subgroup A chitinase genes had higher transcript levels than the genes of all other chitinases. Subgroup B chitinase genes (except ) presented higher transcript levels in chitin medium compared with other conditions. and were mainly transcribed in autolysis medium and in blastospores, respectively. Moreover, presented higher transcript levels than genes of other chitinases. This work provides an overview of the GH18 chitinases and ENGase in and provides a context for the chitinolytic potential, functions, and biological controls of these enzymes of entomopathogenic fungi.