Overexpression of chimeric chitinase42 enhances the antifungal activity of Trichoderma harzianum against Fusarium graminearum

Evidence for the role of chitinases in biocontrol by Trichoderma species has been well documented.Chit42 lacks a chitin–binding domain (ChBD) which is involved in its binding activity to insoluble chitin. The objective of the present study was to enhance antifungal activity of T. harzianum by overexpression of wild type and hybrid forms of Chit42 containing chitin binding domain. To produce chimeric chitinase with improved enzyme activity, the hybrid chitinase was constructed by the adding of ChBD from Rhizopus oligosporus to the C–terminal end of Chit42 cDNA from T. atroviride using SoEing PCR. The recombinant hybrid chitinase (Chit42–ChBD) displayed a 1.56 fold higher chitinase activity than Chit42. This increase suggests that the ChBDmay play a role in helping the enzyme to bind better to the insoluble chitin. Moreover, Chit42–ChBD transformants showed higher antifungal activity towards Fusarium graminearum, the causal agent of Fusarium head blight (FHB) disease in wheat.