1Laboratoire de Biochimie, Biologie cellulaire et Ecologie des Interactions Plantes/Micro-Organismes, UMR 1088 INRA/Université de Bourgogne, 17 rue Sully, BP 86510, 21065 Dijon cedex, France; 2Institut Jules Guyot, Université de Bourgogne, BP 138, 21004 Dijon cedex, France; 3Laboratoire de Phytopathologie, Méthodologie de la Détection, INRA Versailles, Route de Saint Cyr, 78026 Versailles cedex, France; 4Laboratoire de Chimie des Protéines, Département de Biologie Moléculaire et Structurale, CEA-Grenoble, 38054 Grenoble cedex, France; 5Dipartimento di Biologia Vegetale, Universita di Roma La Sapienza, Piazzale Aldo Moro 5, 00185, Roma, Italy; 6Laboratoire de Physiologie et Biochimie Végétales, ESA CNRS 6161, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers cedex, France
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Accepted 12 February 2003.
A purified glycoprotein from Botrytis cinerea(strain T4), identified as endopolygalacturonase 1 (T4BcPG1) by mass spectrometry analysis, has been shown to activate defense reactions in grapevine (Vitis vinifera cv. Gamay). These reactions include calcium influx, production of active oxygen species, activation of two mitogen-activated protein kinases, defense gene transcript accumulation, and phytoalexin production. Most of these defense reactions were also activated in grapevine in response to purified oligogalacturonides (OGA) with a degree of polymerization of 9 to 20. In vivo, these active OGA might be a part of the released products resulting from endopolygalacturonase activity on plant cell walls. Nevertheless, the intensity and kinetics of events triggered by OGA were very different when compared with T4BcPG1 effects. Moreover, chemical treatments of T4BcPG1 and desensitization assays have allowed us to discriminate enzymatic and elicitor activities, indicating that elicitor activity was not due to released oligogalacturonides. Thus, BcPG1 should be considered as both an avirulence and a virulence factor. The role of the secreted BcPG1 in the pathogenicity of Botrytis cinerea is discussed.
© 2003 The American Phytopathological Society