La vigne est soumise à de nombreuses maladies impliquant l'utilisation de produits phytosanitaires en grande quantité dont l'utilisation est néfaste pour l'environnement et la santé des utilisateurs. Un enjeu est donc de développer des méthodes alternatives à la lutte chimique. La protéine codée par le gène NPR1 (Nonexpressor of pathogenesis-related gene 1) joue un rôle clef dans la résistance à large spectre chez les plantes. Des éliciteurs tels que l'acide salicylique ou des agents pathogènes influencent l'activation de NPR1 dans le cytoplasme. La translocation de NPRl dans le noyau et son interaction avec des facteurs de transcription TGA induit l'expression des gênes PR (Pathogenesis-related). Nous avons identifié sept homologues potentiels des gènes NPR1 et TGA chez Vitis vinifera (VvNPR1.1, VvNPR1.2, VvTGA1 à 5). L'étude de la diversité de séquences dans les exons de 15 accessions de Vitaceae indique qu'ils sont soumis à une forte pression de sélection purificatrice. De plus, l'analyse in silico des régions promotrices des VvNPR1 montre la présence, d'éléments cis-régulateurs potentiels, en réponse aux stress biotiques et abiotiques ainsi que des motifs de liaison à des facteurs de transcription. Une étude plus poussée des introns montre quelques éléments transposables et un faible polymorphisme dans six accessions de Vitis vinifera. Ces résultats argumentent en faveur d'une pression de sélection forte agissant sur ces gènes. Ceci nous a mené à formuler des hypothèses fonctionnelles et à réaliser une étude d'interaction avec les facteurs de transcription VvTGA1 et VvTGA4 par la technique du double hybride. Ces derniers n'interagissent pas avec VvNPR 1.1. / Numerous diseases affect grapevine, resulting in the use of phytochemicals in large quantities that are harmful for environment and user's health. In the long term, the aim is to develop alternative methods to chemicals. The protein encoded by NPR1 (Nonexpressor of pathogenesis-related gene 1) plays a pivotal role in conferring broad spectrum pathogen resistance in plants. Activation of NPR 1 in the cytoplasm is influenced by elicitors such as salicylic acid or pathogens associated with the accumulation of reactive oxygen species. Translocation of NPR1 into the nucleus and interaction with TGA transcription factors induce the expression of PR (Pathogenesis-related) genes. Using a candidate gene approach, we have identified seven putative homologs to NPR1 and TGA in the grapevine genome (VvNPR1.1, VvNPR1.2, VvTGA1 to 5). The study of sequence diversity in exons of 15 accessions of the Vitaceae family indicates that these exons are subjected to a strong purifying selection pressure. Moreover, in silico analysis in the promoters of VvNPR1 shows putative cis-regulator elements, in answer to biotic and abiotic stresses as well as link patterns to transcription factors. An intron study shows transposable elements and a low polymorphism in six accessions of Vitis vinifera. These results suggest a strong selection pressure on these genes. Functional hypotheses were formulated, and an interaction study with transcription factors VvTGA1 and VvTGA4 was conducted using a method based on yeast two hybrid, showing that they do not interact with VvNPR1.1.

Plants respond to and defend themselves against a wide range of disease-causing microbes. In order to do so, massive reprogramming of cellular protein expression patterns, which underpin various defense pathways, must occur. A family of basic leucine zipper transcription factors, called TGA factors, has been implicated in mediating this response. The TGA factors themselves are subject to complex regulation; of note, TGA1 and TGA4 are regulated via a reduction of conserved cysteines after treatment with the phenolic signaling molecular salicylic acid, which accumulates following pathogen challenge. Previous studies indicate that TGA factors physically interact in the yeast two-hybrid system with the plant-specific CC-type of glutaredoxin (Grx)-like proteins. Grx are a family of oxidoreductases that are important for maintaining the cellular redox status and often are required to modulate protein activity. The goal of this study was to ascertain the role of these Grx-like proteins in regulating TGA1 redox state. To this end, the expression patterns of several Grx genes were analyzed.<p> Quantitative-reverse-transcriptase PCR (q-RT-PCR) experiments indicated that TGA1 and TGA4 may be involved in down-regulating levels Grx-like gene transcripts after exposure to pathogens or salicylic acid (SA). Furthermore, qRT-PCR experiments also indicated that expression of some Grx-like genes is induced by SA, jasmonic acid (JA), and <i>Pseudomonas syringae</i>. Overexpression of the Grx-like protein, CXXC9, in <i>Arabidopsis thaliana</i> revealed that it is a regulatory factor in the cross-talk between vi theSA/JA pathways as it is able to suppress expression of PDF1.2, a marker for the JA defense pathway, as determined by qRT-PCR. The â-hydroxy ethyl disulfide (HED) assay was utilized to determine if the CC-type of Grx-like proteins have oxidoreductase activity <i>in vitro</i>. These studies revealed that that the Grx-like proteins do not exhibit oxidoreductase activity in this assay.

Plants respond to and defend themselves against a wide range of disease-causing microbes. In order to do so, massive reprogramming of cellular protein expression patterns, which underpin various defense pathways, must occur. A family of basic leucine zipper transcription factors, called TGA factors, has been implicated in mediating this response. The TGA factors themselves are subject to complex regulation; of note, TGA1 and TGA4 are regulated via a reduction of conserved cysteines after treatment with the phenolic signaling molecular salicylic acid, which accumulates following pathogen challenge. Previous studies indicate that TGA factors physically interact in the yeast two-hybrid system with the plant-specific CC-type of glutaredoxin (Grx)-like proteins. Grx are a family of oxidoreductases that are important for maintaining the cellular redox status and often are required to modulate protein activity. The goal of this study was to ascertain the role of these Grx-like proteins in regulating TGA1 redox state. To this end, the expression patterns of several Grx genes were analyzed.<p> Quantitative-reverse-transcriptase PCR (q-RT-PCR) experiments indicated that TGA1 and TGA4 may be involved in down-regulating levels Grx-like gene transcripts after exposure to pathogens or salicylic acid (SA). Furthermore, qRT-PCR experiments also indicated that expression of some Grx-like genes is induced by SA, jasmonic acid (JA), and <i>Pseudomonas syringae</i>. Overexpression of the Grx-like protein, CXXC9, in <i>Arabidopsis thaliana</i> revealed that it is a regulatory factor in the cross-talk between vi theSA/JA pathways as it is able to suppress expression of PDF1.2, a marker for the JA defense pathway, as determined by qRT-PCR. The â-hydroxy ethyl disulfide (HED) assay was utilized to determine if the CC-type of Grx-like proteins have oxidoreductase activity <i>in vitro</i>. These studies revealed that that the Grx-like proteins do not exhibit oxidoreductase activity in this assay.

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