Análisis molecular y proteómico de la bacteria fitopatógena de vid Xylophilus ampelinus

179 p.La necrosis bacteriana es una enfermedad que puede extenderse con facilidad y llegar a provocar grandes pérdidas económicas en viñedos de todo el mundo. La presente tesis doctoral se centra en el estudio de la bacteria que provoca esta patología, la Xylophilus ampelinus. Los objetivos planteados por la autora fueron: desarrollo de una metodología para la valoración de la virulencia de X. ampelinus, aislamiento de mutantes avirulentos o con virulencia atenuada de X. ampelinus, análisis proteómico de X. ampelinus e identificación de factores de patogenicidad de X. ampelinus

Effectiveness of natural antifungal compounds in controlling infection by grapevine trunk disease pathogens through pruning wounds

[EN] Grapevine trunk fungal pathogens, such as Diplodia seriata and Phaeomoniella chlamydospora, can infect plants through pruning wounds. They cause grapevine trunk diseases and are involved in grapevine decline. Accordingly, the protection of pruning wounds is crucial for the management of grapevine trunk diseases. The efficacy of different natural antifungals in inhibiting the growth of several fungi causing grapevine trunk diseases was evaluated in vitro. The fungi showing greater in vitro efficacy were tested on autoclaved grape wood assays against D. seriata and P. chlamydospora. Based on results from these assays, chitosan oligosaccharide, vanillin, and garlic extract were selected for further evaluation on pruning wounds inoculated with D. seriata and P. chlamydospora in field trials. A significant decrease in plant mortality was observed after 2 years of growth in the plants treated with the different natural antifungals compared to the mortality rate observed in infected plants that were not treated with antifungals. Also, the infection rate for the inoculated pathogens was significantly reduced in plants treated with the selected natural antifungals. Therefore, natural antifungals represent a promising alternative for disease control and could provide significant economic benefits for the grape-growing industrySIThis work was financed by Bodegas Vega Sicilia S.A. (Valbuena de Duero, Valladolid, Spain

Manganese transporter protein MntH is required for virulence of Xylophilus ampelinus, the causal agent of bacterial necrosis in grapevine

This journal is published by Hindawi as part of a publishing collaboration with the Australian Society of Viticulture and Oenology. It is a fully open access journal produced under the Hindawi and Wiley brands[EN] Background and Aims: The aim of this study is to identify proteins involved in the pathogenicity/virulence of Xylophilus ampelinus. Characterisation of these proteins could provide new insights into putative targets for controlling bacterial necrosis in grapevines. Methods and Results: Transposon insertion mutagenesis was used to isolate X. ampelinus mutants exhibiting an altered virulence. Characterisation of one of the avirulent mutants revealed the insertion of a transposon into the mntH gene encoding the major manganese transporter. Virulence tests on grapevine leaves clearly showed that the virulence of these mutants was significantly reduced. Phenotypic analysis of an mntH mutant indicated that the MntH protein is a Mn++ transporter but that MntH does not play a significant role in the transport of Fe++ or Cu++. The MntH mutants exhibited an increased sensitivity to hydrogen peroxide, although catalase and superoxide dismutase activities were not significantly affected. Conclusion: The MntH protein plays a significant role in the virulence of X. ampelinus. Significance of the Study: This is the first report showing that transposon mutagenesis is an effective strategy for the isolation of X. ampelinus mutants. It is also the first report characterising a gene encoding a protein involved in virulence in this grapevine pathogenSIThis work was financed by a Research Contract sponsored by Bodegas Vega Sicilia S.A. (Valbuena de Duero, Valladolid, Spain