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

Fungal chitinases play essential roles in chitin degradation, cell wall remodeling, chitin recycling, nutrition acquisition, autolysis and virulence. In this study, eighteen glycoside hydrolase family (GH) 18 genes were identified in the Isaria cicadae genome. Seventeen of them belonged to chitinases and one was an endo-β-N-acetylglucosaminidase (ENGase). Based on the 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, S/AxGG, CBM1, CBM18 and CBM50 domains were detected in I. cicadae chitinases and ENGase. Results of expression patterns showed that PCchiA1, A6, B1 and B4 had high transcript levels in the different growth conditions or developmental stages. SgA chitinase genes had higher transcript levels compared to all other chitinases. SgB genes (except PCchiB7) presented higher transcript levels in chitin medium compared to other conditions. PCchiC2 and PCchiC3 were mainly transcribed in autolysis medium and in blastospores, respectively. Moreover, PCchiB1 presented higher transcript levels compared to other chitinases. This work provides an overview of the GH18 chitinases and ENGase in I. cicadae, and provides a context for the chitinolytic potential, functions, and biological controls of these enzymes of entomopathogenic fungi.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author