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RESEARCH PRODUCT

Identification of the VvFLS2 grapevine flagellin receptor by a functional genomics strategy

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National audience; Grapevine (Vitis vinifera) is a crop of high agronomic interest subject to many destructive diseases. Pattern recognition receptors (PRRs) mediate detection of potential pathogens via the perception of pathogen associated molecular patterns (PAMPs), which is important for plant disease resistance. A well studied PRR is the Arabidopsis leucine-rich repeat receptor kinase FLS2 that recognizes bacterial flagellin (or its minimal motif flg22). Flagellin perception plays an important role in restricting bacterial invasion into plant leaves. Until now, functional FLS2 orthologues have been characterized in Nicotiana benthamiana, rice and tomato. Despite its economical importance and its recently sequenced genome, no PRRs have been discovered in grapevine so far. The aim of this project is the identification of functional grapevine FLS2 orthologue, which would provide the first example of a grapevine PAMP/PRR couple. We have shown that flg22 triggers a battery of defense responses, similarly to ones triggered in Arabidopsis or N. benthamiana. We could measure early responses, such as bursts of reactive oxygen species, variations in free cytosolic calcium and MAPK activation. In addition, flg22 treatment induced expression of defense genes encoding phytoalexin-related stilbene synthase (STS1), glucanase (PR2) or the protease inhibitor (PR6). Then, we identified the putative grapevine FLS2 orthologue by an in silico approach. We could demonstrate the functionality of VvFLS2 by complementation of the Arabidopsis fls2 null mutant. In parallel, a silencing approach in grapevine was developed to obtain stable transgenic lines in which the expression of VvFLS2 is reduced. The success of this strategy is currently being assessed based on flg22-induced defense gene expression. The identification of a functional FLS2 receptor in Vitis vinifera species and the antisense Vvfls2 lines generated open the door to subsequent studies of FLS2 involvement in grapevine resistance to bacterial infections.