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A β-1,3 Glucan Sulfate Induces Resistance in Grapevine against Plasmopara viticola Through Priming of Defense Responses, Including HR-like Cell Death

¹Unité Mixte de Recherches INRA-CNRS-Université de Bourgogne, Plante-Microbe Environnement, INRA, 17 Rue Sully, BP 86510, 21065 Dijon cedex, France; ²Laboratoire de Stress, Défenses et Reproduction des Plantes. Faculté de Sciences Exactes et Naturelles, Moulin de la Housse, BP 1039, 51687 Reims cedex 2, France; ³Moët et Chandon, 6 Rue Croix de Bussy, 51200 Epernay, France; ⁴Laboratoires Goëmar, Avenue du Général Patton, 35400 Saint-Malo, France

Sulfated laminarin (PS3) has been shown previously to be an elicitor of plant defense reactions in tobacco and Arabidopsis and to induce protection against tobacco mosaic virus. Here, we have demonstrated the efficiency of PS3 in protecting a susceptible grapevine cultivar (Vitis vinifera cv. Marselan) against downy mildew (Plasmopara viticola) under glasshouse conditions. This induced resistance was associated with potentiated H₂O₂ production at the infection sites, upregulation of defense-related genes, callose and phenol depositions, and hypersensitive response-like cell death. Interestingly, similar responses were observed following P. viticola inoculation in a tolerant grapevine hybrid cultivar (Solaris). A pharmacological approach led us to conclude that both callose synthesis and jasmonic acid pathway contribute to PS3-induced resistance.