Modified Cyclodextrins Are Chemically Defined Glucan Inducers of Defense Responses in Grapevine Cell Cultures

In grapevine (Vitis vinifera L.), defense responses after microbial infection or treatment with elicitors involve accumulation of phytoalexins, oxidative burst, and the synthesis of pathogenesis-related proteins. Oligosaccharide fractions from fungal or algal cell walls efficiently induce the defense responses, but a detailed analysis of the elicitor-plant cell surface interaction at the molecular level is precluded by the lack of chemically pure oligosaccharide elicitors. A grapevine liquid cell culture system was used to examine the properties of cyclodextrins (CDs) as inducers of defense responses. This work shows that the chemically pure heptakis(2,6-di-O-methyl)-betaCD caused a dramatic extracellular accumulation of the phytoalexin resveratrol and changes in peroxidase activity and isoenzymatic pattern. Other modified CDs tested on several grapevine cell lines resulted in different eliciting capacities of CDs and different sensibilities of the cell lines. The spent medium of elicited cultures was shown to disturb Botrytis cinerea growth in a plate assay.