In this study, a chitinase gene (DrChit) that plays a role in the carnivorous processes of Drosera rotundifolia L. was isolated from genomic DNA, linked to a double CaMV35S promoter and nos terminator in a pBinPlus plant binary vector, and used for Agrobacterium-mediated transformation of tobacco. RT-qPCR revealed that within 14 transgenic lines analysed in detail, 57% had DrChit transcript abundance comparable to or lower than level of a reference actin gene transcript. In contrast, the transgenic lines 9 and 14 exhibited 72 and 152 times higher expression level than actin. The protein extracts of these two lines exhibited five and eight times higher chitinolytic activity than non-transgenic controls when measured in a fluorimetric assay with FITC-chitin. Finally, the growth of Trichoderma viride was obviously suppressed when the pathogen was exposed to 100 μg of crude protein extract isolated from line 9 and line 14, with the area of mycelium growth reaching only 56.4% and 45.2%, of non-transgenic control, respectively. This is the first time a chitinase from a carnivorous plant with substrate specificity for long chitin polymers was tested in a transgenic plant with the aim of exploring its antifungal potential.
Keywords: Antifungal activity; Chitinase; Chitinolytic activity; Drosera rotundifolia; FITC-chitin; Transgenic plants.