Proteome approach to characterize proteins induced by antagonist yeast and salicylic acid in peach fruit.

Proteins induced by antagonist yeast Pichia membranefaciens and salicylic acid (SA) in peach fruit were determined using proteome analysis in this study. Both the yeast and SA enhanced the resistance of peach fruit and delayed the initiation infection of Penicillium expansum. When quadrupole time-of-flight tandem mass spectrometer was used, a total of 25 proteins could be identified as significantly up- or down-regulated in response to at least one activitor. According to the function, these proteins were attributed to protein metabolism, defense response, transcription, energy metabolism, and cell structure. Among them, 6 antioxidant and 3 pathogenesis-related (PR) proteins were induced by P. membranefaciens or SA treatments. The induction results of these proteins were related to treatment time. Six other proteins were identified as the enzymes which catalyze the reactions of glycolysis and tricarboxylic acid cycle. In addition, both the yeast and SA treatments enhanced the transcript and translation expression of the catalase gene. These results suggested that antioxidant and PR proteins, as well as enzymes associated with sugar metabolism, were involved in resistance of peach fruit induced by P. membranefaciens and SA.