RESUMEN
Studying grapevine (Vitis vinifera) innate defense mechanisms is a prerequisite to the development of new protection strategies, based on the stimulation of plant signaling pathways to trigger pathogen resistance. Two transcriptional coactivators (VvNPR1.1 and VvNPR1.2) with similarity to Arabidopsis thaliana NPR1 (Non-Expressor of PR genes 1), a well-characterized and key signaling element of the salicylic acid (SA) pathway, were recently isolated in Vitis vinifera. In this study, functional characterization of VvNPR1.1 and VvNPR1.2, including complementation of the Arabidopsis npr1 mutant, revealed that VvNPR1.1 is a functional ortholog of AtNPR1, whereas VvNPR1.2 likely has a different function. Ectopic overexpression of VvNPR1.1 in the Arabidopsis npr1-2 mutant restored plant growth at a high SA concentration, Pathogenesis Related 1 (PR1) gene expression after treatment with SA or bacterial inoculation, and resistance to virulent Pseudomonas syringae pv. maculicola bacteria. Moreover, stable overexpression of VvNPR1.1-GFP in V. vinifera resulted in constitutive nuclear localization of the fusion protein and enhanced PR gene expression in uninfected plants. Furthermore, grapevine plants overexpressing VvNPR1.1-GFP exhibited an enhanced resistance to powdery mildew infection. This work highlights the importance of the conserved SA/NPR1 signaling pathway for resistance to biotrophic pathogens in V. vinifera.
Asunto(s)
Antiinfecciosos/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Vitis/genética , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Arabidopsis/microbiología , Arabidopsis/fisiología , Ascomicetos/fisiología , Regulación de la Expresión Génica de las Plantas , Datos de Secuencia Molecular , Mutación , Inmunidad de la Planta , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Plantas Modificadas Genéticamente/microbiología , Plantas Modificadas Genéticamente/fisiología , Pseudomonas syringae/fisiología , Ácido Salicílico/metabolismo , Transducción de Señal , Factores de Tiempo , Vitis/metabolismo , Vitis/microbiología , Vitis/fisiologíaRESUMEN
BACKGROUND: Limiting the use of fungicides is due to become an important issue in managing Erysiphe necator (Schwein) Burrill infections in vineyards. The authors determined how three fungicides currently used by vine growers could be managed to control the early stages of an E. necator-induced epidemic. RESULTS: Leaf-disc bioassays and field experiments suggested that the protectant quinoxyfen induced minor disruption in E. necator development, but compounds with protectant and curative properties (tebuconazole and trifloxystrobin) caused significant, although different, disruption during E. necator-induced epidemics. Bioassays showed that each of the antifungals were most effective at different stages of fungal development, tebuconazole before sporulation and trifloxystrobin after sporulation of the colonies. Results from the bioassay also highlighted likely occurrences in the field, where several stages of fungal development are encountered simultaneously. CONCLUSION: The present findings were complementary: leaf-disc tests showed when the fungicides were most effective at inhibiting E. necator infection cycles; the field trial provided results in terms of incidence and severity of disease on bunches without reference to the pathogenic cycle development. A protection strategy combining the different types of fungicide under study is suggested.
