Expression and antifungal activity of chitinase from biocontrol agent Bjerkandera adusta

Abstract:

In order to explore the biological control potential of Bjerkandera adusta BK-1, this study tested the disease resistance effect of BK-1 with the antifungal activity. And used RT-qPCR to analyze the expression levels of eight cell-wall lyase genes of B. adusta strain BK-1. The results showed that in response to six pathogenic fungi (Alternaria alternata, Alternaria alternata f. sp. mali, Alternaria solani, Alternaria tenuissima, Fusarium oxysporum and Botrytis cinerea), the expression of the chitinase gene BaCHIB was up-regulated by 27.3 to 50.3 times expression of,which is much higher than the other seven candidate genes. BaCHIB belongs to the glycoside hydrolase 18 family (GH 18), and has the Chic_BD (aromatic chitin/cellulose-binding site residues) domain, a domain that belongs to the chitinase subgroup B (CHIB). Combined with the analysis of disease resistance in planta, the up-regulation of the gene induced expression is highly synchronized with the appearance of disease resistance. And the exogenously expressed protein BaCHIB extracted from the Pichia pastoris expression system showed high chitinase and significant antifungal activity against a variety of plant-pathogenic fungi, including Alternaria alternata, Alternaria solani and Botrytis cinerea. This result showed that BaCHIB has a fungicide activity.