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Molecular Basis of Ergosterol-Induced Protection of Grape Against Botrytis cinerea: Induction of Type I LTP Promoter Activity, WRKY, and Stilbene Synthase Gene Expression

¹Laboratoire de Physiologie et Biochimie Végétales, UMR CNRS 6161, Université de Poitiers, Bâtiment Botanique, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France; ²Institut de Biologie Végétale Moléculaire, UMR 619 Physiologie et Biotechnologies végétales, Université Bordeaux1-Université Bordeaux2-INRA, 71, Av. Edouard Bourlaux, 33883 Villenave d'Ornon, France

Type I lipid transfer proteins (LTPs) are basic, 9-kDa cystein-rich proteins believed to be involved in plant defense mechanisms. A 2,100-bp fragment containing the coding region of Vitis vinifera lipid transfer protein 1 (VvLTP1) and 1,420-bp of its promoter region was isolated by screening a grape genomic library. In silico analysis revealed several putative, defense-related, cis-regulatory elements such as W- and MYB-boxes, involved in the binding of WRKY and MYB transcription factors, respectively. The 5′-truncated versions of the VvLTP1 promoter were generated, cloned in front of the β-glucuronidase (GUS) reporter gene, and introduced in tobacco plants and grapevine cell suspensions using Agrobacterium spp. Single MYB- and the W-boxes identified on the 0.250-kbp fragment were sufficient to induce GUS activity in transgenic tobacco plants after transient expression of MYB and WRKY. Ergosterol, a nonspecific fungal elicitor, induced GUS activity in transgenic grapevine cell suspensions transformed with the 1,420- and 750-bp promoter containing a palindromic arrangement of two Wboxes but not the 650- or 250-bp fragment, where only one W-box was present. Moreover, ergosterol triggered WRKY, VvLTP1, and stilbene synthase gene expression in grape plantlets and enhanced protection against Botrytis cinerea. The molecular basis of ergosterol-induced protection is discussed.

Additional keyword: phytoalexin .