Induction of resistance by salicylic acid (SA) exogenous treatment is a complementary approach to control plant diseases. SA effect on Potato virus X (SPCP1 strain) - infected tomato plants was examined by analyzing their physiological parameters and proteomic profiling at initial infection. PVX-SPCP1 altered photosynthesis and carbohydrate synthesis proteins and elicited stress proteins. SA partially offset reduction in photosynthetic rate during infection by increasing mesophyll conductance. SA counteracted these changes through stabilization of photosystem II, increased proteins related with thermotolerance and stress, and decreased proteins related with stomatal opening. The strongest effects of SA occurred at the beginning of the pathogenesis cycle. (C) 2015 Elsevier Ltd. All rights reserved.