Chitosan treatment induces changes of protein expression profile and stilbene distribution in Vitis vinifera cell suspensions

Polyphenols, including stilbenes and flavonoids, are an essential part of human diet and constitute one of the most abundant and ubiquitous groups of plant secondary metabolites, and their level is inducible by stress, fungal attack or biotic and abiotic elicitors. Proteomic analysis of Vitis vinifera (L.) cultivar (cv.) Barbera grape cell suspensions, showed that the amount of 73 proteins consistently changed in 50 mg/mL chitosan-treated samples compared with controls, or between the two controls, of which 56 were identified by MSanalyses. In particular, de-novo synthesis and/ or accumulation of stilbene synthase proteins were promoted by chitosan which also stimulated trans-resveratrol endogenous accumulation and decreased its release into the culture medium. No influence was shown on cis-resveratrol. There was no effect on the accumulation of total resveratrol mono-glucosides (trans- and cis-piceid and trans- and cis-resveratroloside). Throughout the observation period the upregulation of phenylalanine ammonia lyase, chalcone synthase, chalcone-flavanone isomerase (CHI) transcript expression levels well correlated with CHI protein amount and with the accumulation of anthocyanins. Chitosan treatment strongly increased the expression of eleven proteins of the pathogenesis related protein-10 family, as well as their mRNA levels.