Chitosan-elicited defense responses in Cucumber mosaic virus (CMV)-infected tomato plants

Abstract

The control of plant diseases by inducing plant resistance responses represents an interesting solution to avoidyield losses and protect the natural environment. Hence, the intertwined relationships between host, pathogenand inducer are increasingly subject of investigations. Here, we report the efficacy of chitosan-elicited defenseresponses inSolanum lycopersicumvar.cerasiformeplants againstCucumber mosaic virus(CMV). Chitosan wasapplied via foliar spray before the CMV inoculation to verify its effectiveness as a preventive treatment againstthe viral infection. Virus accumulation, photosynthetic performance, as well as genes encoding for proteinsaffecting resistance responses and biosynthetic pathways, were investigated. It was observed a significant re-duction of CMV accumulation in chitosan-treated plants that were successively infected with CMV, compared toonly CMV-infected ones (up to 100%). Similarly, a positive effect of chitosan on gas exchange dynamics wasrevealed. The analysis of gene expression (CEVI-1,NPR1,PSY2andPAL5) suggested the occurrence of chitosan-induced, systemic acquired resistance-related responses associated with a readjustment of the plant’s oxidativestatus. In addition, the absence of deleterious symptoms in chitosan-treated successively CMV-infected plants,confirmed that chitosan can be used as a powerful control agent. Our data indicate that chitosan, when pre-ventively applied, is able to elicit defense responses in tomato to control CMV infection. Suchfinding may berecommended to protect the tomato fruit yields as well as other crops