ROLB INCREASES RESISTANCE TO PSEUDOPYRENOCHAETA LYCOPERSICI IN TOMATO PLANTS AND MODULATES DEFENCE RELATED GENE EXPRESSION

Pseudopyrenochaeta lycopersici is the soil-borne hemi-biotrophic fungal pathogen responsible for corky root rot (CRR) disease in tomato, characterized by brown, necrotic lesions on the roots. Tomato is one of the most important vegetables consumed worldwide, and the disease has the potential to cause significant yield loss both in the greenhouse and in the field, causing up to 75% of losses in fruit yield. It is well documented from literature the role for rolB in enhancing plant resistance to fungal pathogens activating physiological reactions, including ROS, and programmed cell death. In the frame of improving tomato plants resistance, we tested the transgenic tomato expressing rolB under its endogenous promoter, following infection with P. lycopersici. We demonstrated that rolB confers tomato tolerance against P. lycopersici. Comparison of rolB and wild type tomato plants upon infection, showed increased expression of several genes involved in defense response, as chitinase, WRKY40 transcription factor, osmotin, glucanase, lipoxygenase and ERF97, both in roots and leaves. Some of these genes are also known for inducing a hypersensitive response and ROS production at the site of infection, so the quantification of ROS accumulation in rolB and wild type plants after infection by P. lycopersici is currently under study. Moreover, the analysis of expression level of some genes controlling free radical formation is in progress, in order to identify some candidate genes putatively involved in resistance/tolerance response of tomato to infection.