Defense-related gene expression and enzyme activities in transgenic cotton plants expressing an endochitinase gene from Trichoderma virens in response to interaction with Rhizoctonia solani

There are many reports on obtaining disease-resistance trait in plants by overexpressing genes from diverse organisms that encode chitinolytic enzymes. Current study represents an attempt to dissect the mechanism underlying the resistance to Rhizoctonia solani in cotton plants expressing an endochitinase gene from Trichoderma virens. Several assays were developed that provided a powerful demonstration of the disease protection obtained in the transgenic cotton plants. Transgene-dependent endochitinase activity was confirmed in various tissues and in the medium surrounding the roots of transformants. Biochemical and molecular analyses conducted on the transgenic plants showed rapid/greater induction of ROS, expression of several defense-related genes, and activation of some PR enzymes and the terpenoid pathway. Interestingly, even in the absence of a challenge from the pathogen, the basal activities of some of the defense-related genes and enzymes were higher in the endochitinase-expressing cotton plants. This elevated defensive state of the transformants may act synergistically with the potent, transgene-encoded endochitinase activity to confer a strong resistance to R. solani infection.