Profiling and accurate quantification of trans-resveratrol,trans-piceid, trans-pterostilbene and 11 viniferins induced by Plasmopara viticola in partially resistant grapevine leaves

Background and Aims:  In the Vitaceae, stilbenoid viniferins constitute a relatively restricted group of molecules based on a trans-resveratrol structure and represent the main known phytoalexins. The aim of this work was the development of a new method for the chromatographic separation and accurate quantification of viniferins found in grapevine leaves following infection with Plasmopara viticola. Methods and Results:  An interspecific F1 population was used, deriving from the cross between Merzling and Teroldego, respectively, partially resistant and susceptible to P. viticola. Analysis was carried on a liquid chromatography-mass spectrometry (LC-MS) system, using a reverse phase column. A method was validated for detailed metabolite profiling, with accurate identification and quantification of trans-resveratrol, trans-piceid, trans-pterostilbene, a condensation product between (+)-catechin and caffeic acid, and the whole class of stilbenoid viniferins in P. viticola-infected grapevine leaves, using their respective standards. Synthesis was ongoing, and 6 days after infection, it was possible to see the highest concentration of stilbenoids for all genotypes. On the other hand, the intensity of stilbene induction did not show a clear and homogeneous correlation with the position of the leaves in the young shoot. Conclusions:  The method described in this paper provides the basis for performing in a single run a targeted analysis of resveratrol, piceid, pterostilbene and the whole class of stilbenoids in P. viticola-infected grapevine genotypes. Significance of the Study:  To our knowledge, this is the first paper that has reported on detailed metabolite profiling with accurate identification and quantification of the main viniferins in grape leaves following infection with P. viticola, using the respective standards.