7 research outputs found
VvNPR1.1 est lâorthologue dâAtNPR1 et sa surexpression provoque lâactivation constitutive des gĂšnes PR et la rĂ©sistance Ă Erysiphe necator chez Vitis vinifera
La comprĂ©hension des bases molĂ©culaires des mĂ©canismes de rĂ©sistance de la Vigne aux agresseurs biotiques constitue un prĂ©requis Ă la recherche de moyens de lutte alternatifs aux pesticides. Chez Arabidopsis, NPR1 (Non expressor of PR genes 1) joue un rĂŽle clĂ© dans la voie de signalisation rĂ©gulĂ©e par lâacide salicylique et responsable de la mise en place de la rĂ©sistance aux agents pathogĂšnes biotrophes et de la rĂ©sistance systĂ©mique acquise (SAR). Nous avons identifiĂ© deux gĂšnes homologues dâAtNPR1 chez la Vigne : VvNPR1.1 et VvNPR1.2. La caractĂ©risation fonctionnelle de ces deux gĂšnes montre que la surexpression de VvNPR1.1 dans le mutant npr1-2 dâArabidopsis permet, contrairement `a VvNPR1.2, de restaurer lâexpression de PR1 aprĂšs traitement par du SA ou inoculation bactĂ©rienne, ainsi que la rĂ©sistance Ă Pseudomonas syringae pv. maculicola, un
agent pathogĂšne virulent. VvNPR1.1 apparaĂźt donc comme lâorthologue fonctionnel dâAtNPR1, alors que VvNPR1.2 assure vraisemblablement une fonction diffĂ©rente. La surexpression stable de VvNPR1.1 en fusion avec la GFP a Ă©galement pu ĂȘtre rĂ©alisĂ©e chez V. vinifera cv. Chardonnay, grĂące Ă une technique de transformation par A. tumefaciens de cals embryogĂšnes de Vigne. Les rĂ©sultats obtenus sur les plantules transformĂ©es montrent une localisation constitutive de VvNPR1-GFP dans
le noyau, ainsi quâune expression Ă©levĂ©e des protĂ©ines PR en lâabsence dâinfection. De plus, les vignes surexprimant VvNPR1-GFP montrent clairement une augmentation de la rÂŽesistance vis-Ă -vis de lâinfection par Erysiphe necator, lâagent de lâoĂŻdium. La forte conservation de sĂ©quence des gĂšnes VvNPR1 chez les Vitaceae ainsi que lâensemble de ces rĂ©sultats souligne lâimportance de la voie rĂ©gulĂ©e par le SA et NPR1 pour la rĂ©sistance aux agents pathogĂšnes biotrophes chez la Vigne
Gypsophila paniculata root saponins as an environmentally safe treatment against two nematodes, natural vectors of grapevine fanleaf degeneration
International audienceBackground and Aims: Xiphinema index and X. diversicaudatum are nematodes that transmit the grapevine fanleaf virus and the Arabis mosaic virus, respectively. These viruses are the two agents mainly responsible for the disease that causes the most economic damage to grapevines worldwide. The infectious degeneration of grapevines affects vine performance and grape composition. The control of Xiphinema populations by soil disinfection is now impossible because of the removal from the market of the last available chemical treatments. In this study, saponins are assessed as an alternative treatment to control nematode populations. Methods and Results: The nematicidal effect of saponins from Gypsophila paniculata roots was tested against X. index and X. diversicaudatum. In aqueous media, a concentration of 1 mg/mL was associated with a mortality of greater than 95% in both nematodes, while in rearing soil, 73% of X. index and 85% of X. diversicaudatum were killed by 150 ÎŒg of saponins per gram of soil. In addition, an ecotoxicological study was undertaken on two soil bio-indicators (the mycorrhizal fungus Glomus mosseae and soil nitrification) that revealed that they were not affected by Gy. paniculata saponins at a nematicidal concentration. In the soil, investigation of the major Gy. paniculata root saponins revealed that these molecules were completely degraded in the soil within 4 days. Conclusion: We show that Gy. paniculata saponins are an efficient and environmentally friendly treatment against two nematodes that transmit grapevine fanleaf virus. Significance of the Study: This saponin-based alternative to chemical treatments could provide an environmentally safe and efficient solution for vine growers to use against grapevine fanleaf vector nematodes
Protoplasma
Botryosphaeria dieback, esca and Eutypa dieback are three economic major grapevine trunk diseases that cause severe yield reduction in vineyards worldwide. The frequency of disease symptoms has increased considerably over the past decade, and no efficient treatment is currently available to control these diseases. The different fungi associated with grapevine trunk diseases mainly induce necrotic wood and characteristic foliar symptoms. In this context, fungi virulence factors and host invasion are not well understood. We hypothesise that extracellular proteins produced by Diplodia seriata and Neofusicoccum parvum, two causal agents associated with Botryosphaeria dieback, are virulence factors responsible for the pathogenicity. In our previous work, we demonstrated that the total extracellular compounds produced by N. parvum induced more necrosis on Chardonnay calli and triggered a different defence gene expression pattern than those produced by D. seriata. Furthermore, this aggressiveness was not clearly correlated with the production of mellein, a characteristic phytotoxin of Botryosphaeriaceae, in our in vitro calli model. To characterise other potential virulence factors and to understand the mechanisms of host invasion by the fungus, we evaluated the profile, quantity and the impact of extracellular proteins produced by these fungi on Vitis vinifera calli necrosis and defence gene expression. Our results reveal that, under the same conditions, N. parvum produces more extracellular proteins and in higher concentrations than D. seriata. With Vitis vinifera cv. Chardonnay cells, we showed that equivalent concentrations of proteins secreted by N. parvum were more aggressive than those of D. seriata in producing necrosis and that they clearly induced more grapevine defence genes