ß-1,4 cellodextrins, ß-1,3 glucans and a-1,4 oligogalacturonides are potent elicitors of various defense-related responses in grapevine

International audiencePlant cell-wall degradation products can be considered as ‘microbe-induced molecular patterns’ (MIMPs) recognized through plant receptors as ‘pathogen-induced modified self’. So cell-wall oligosaccharides originating from plants can play an important role in the perception of the invading pathogen by the plant. Cellodextrins (CD) are the end-products from cellulose degradation in plant cell walls, consisting og a linear ß-(1,4) linked glucose backbone. The role of these oligosaccharides in triggering plant defense reactions has not yet been established. Here, we investigated the elicitor activity of CD oligomers in grapevine cells. We show that CD triggered induction oxidative burst, transient elevation of [Ca2+]cyt, expression of dense-related genes, and stimulation of chitinase and ß-1,3 glucanase activities in a CD size-dependent manner. Most of these defense reactions were also induced by linear ß-1,3 glucans (ßGlu) and a-1,4 oligogalacturonides (OGA) of different degree of polymerization (DP), but the intensity of some reactions induced by CD was different when compared with ßGlu and OGA effects. Moreover, desensitization assays using H2O2 production showed that cells treated with CD remained fully responsive to a second application of OGA, suggesting a different mode of perception of these oligosaccharides by grape cells. None of CD, ßGlu, or OGA induced HSR gene expression nor did they induce cell death. We suggest that CD could operate via other distinct reaction pathways than Glu and OGA. Our results also highlight the importance of cellulose-derived ß-1,4-glucans as potent MIMPs in plant defense mechanisms