Expression of a fungal endochitinase gene in transgenic tomato and tobacco results in enhanced tolerance to fungal pathogens.

Abstract

Development of transgenic Nicotiana tabacum and Lycopersicon esculentum expressing an endochitinase (ech42) gene from biocontrol fungus Trichoderma virens using Agrobacterium-mediated genetic transformation is reported in this paper. Integration of transgene in the genome of transgenic plants was demonstrated using polymerase chain reaction and Southern-blot hybridization, while expression was ascertained by reverse transcription polymerase chain reaction. Histochemical analysis confirmed the expression of GUS enzyme in transformed shoots. Levels of endochitinase enzyme in transgenic plants were found to be up to 10 fold higher compared to control plants. Endochitinase enzyme of 42 kDa was also visualized on SDS-PAGE gel using fluorimetric zymogram in transgenic plants. Endochitinase activity was found to be higher in leaf and stem than the root tissue in transgenic tomato plants. Transgenic lines of both plants showed enhanced resistance to fungal pathogens and a strong negative correlation was found between expression level of endochitinase enzyme and size of disease lesions. Inheritance of transgene, expression and resistance to fungal pathogens of T1 transgenic tobacco lines was also analysed. The results of the present studies show that ech42 is a promising candidate gene for developing fungal disease resistance in tomato plants.