Identification of two group A chitinase genes in Botrytis cinerea which are differentially induced by exogenous chitin.

Chitin-degrading enzymes represent potential targets for pesticides in the control of plant pathogenic fungi. Here we describe the cloning, molecular characterization, and expression analysis of two putative chitinases of Botrytis cinerea, a pathogenic fungus infecting a wide range of plants. On the basis of conserved motifs from family 18 of the glycosyl hydrolases and group A of the fungal chitinases, two fragments (BcchiA and BcchiB) were cloned and sequenced. Expression of BcchiA and BcchiB chitinase genes upon growth under different conditions was analysed using RT-PCR. We observed that BcchiA expression was suppressed by glucose, whereas it was strongly stimulated in the presence of chitin or chitin degradation products. Conversely, BcchiB expression was not suppressed by glucose and was not stimulated by chitin or chitin degradation products. The difference in expression regulation is indicative of a functional divergence between the two chitinase paralogous genes.