Plant responses to tomato chlorotic mottle virus: Proteomic view of the resistance mechanisms to a bipartite begomovirus in tomato

Tomato chlorotic mottle virus (ToCMoV) is a widespread bipartite Begomovirus species found in tomato fields in Brazil. In this study, plant responses and putative mechanisms associated with the 'Tyking'-derived recessive resistance to ToCMoV were investigated. Changes in the protein profile in the inoculated plants of two near isogenic tomato lines resistant ('LAM 157') and susceptible ('Santa Clara') to ToCMoV were analyzed. Seedlings were biolistically inoculated with an infectious ToCMoV clone. Leaves from infected plants (confirmed by PCR) were sampled at 15days after inoculation. Proteins were extracted using phenol and analyzed by shotgun MS (2D-nanoUPLC/HDMS^E). Out of the 534 identified proteins, 82 presented statistically significant differences in abundance, including 35 unique proteins displayed in the resistant tomato inoculated with ToCMoV. Proteins associated to chromatin structure, cytoskeleton structure, cuticle biosynthesis, and ubiquitin pathway were identified and their putative roles during virus infection process were discussed. The protein profile analysis allowed for the development of a hypothetical model showing how the resistant host cell responds to ToCMoV infection. The data obtained provide a better understanding of resistant mechanisms used by the host plant to contain viral infection and could be the basis for further investigation in other plant-begomovirus pathosystems.

Biological significance: In this study we propose a model of resistance to begomovirus in tomato and highlight host proteins, which could be targets for future investigations in plant-begomovirus pathosystems.