Overexpression of the chimeric chitinase (ChBD) gene in Lycopersicon esculentum L. enhanced resistance to Sclerotinia sclerotiorum

Tomatoes are an essential part of the human diet worldwide, and their production has been restricted by fungal disease. One of the most common fungal diseases of Lycopersicon esculentum L. is Sclerotinia stem rot, caused by Sclerotinia sclerotiorum . In this work, overexpression of the chimeric chit42 gene from Trichoderma atroviride with Serratia marcescens Chitinase B C-terminal fused chitin-binding domain (ChBD) in tomato was reported. Thirty independent transgenic lines were regenerated and adapted to greenhouse conditions. Five transgenic lines was selected for subsequent molecular and biological analysis. RT-PCR analysis of transgenic plants showed different expression patterns in independent transgenic events. Young leaves of T 1 plants challenged with S. sclerotiorum revealed that expression of chimeric chitinase enhanced plant resistance against sclerotinia stem rot. A radial diffusion assay showed that transgenic lines with constitutive expression of the ChBD gene inhibited S. sclerotiorum growth significantly. Lesion sizes of transgenic tomatoes caused by S. sclerotiorum were significantly reduced compared to non-transgenic tomato plants. This is the first study reporting the evaluation of transgenic lines of tomato harboring Trichoderma chitinase (chit42) with chitin binding domain (ChBD) gene for resistance to one of the most important fungal diseases, S. sclerotiorum .