Downy mildew: is resistance linked to inoculum concentration?

Leaves of different Vitis vinifera cultivars, susceptible (‘Chasselas’ and ‘2185’), less susceptible (‘2142’) or resistant to downy mildew ('Solaris’ and ‘2091’), were inoculated with four different concentrations of an aqueous sporangia suspension of Plasmopara viticola (5 × 105, 2 × 105, 6 × 104 and 2 × 104 sporangia·ml-1). The infection rate of these samples was then examined by light microscopy and synthesis of stilbenes was analysed at infection sites. Infection rate increased parallel with inoculum concentration, but there was no correlation between the infection rate and resistance to P. viticola. Moreover, at the lowest inoculum concentration, the infection rate is similar for susceptible and resistant grapevine varieties. Quantification of stilbenes at 72 hpi showed that at the lowest inoculum concentration, the most susceptible grape variety synthesized the largest amount of stilbenes, whose level remained however below the ED50 values defined for each of them. Conversely, at the highest inoculum concentration, the most resistant varieties produced the highest amounts of the most toxic stilbenes against P. viticola. The critical role of the inoculum concentration used for artificial inoculation to evaluate grapevine resistance to downy mildew is discussed.

Leaf morphological characteristics and stilbene production differently affect downy mildew resistance of Vitis vinifera varieties grown in Italy

The degree of resistance to downy mildew of grape varieties belonging to the oenological tradition of Central Italy was evaluated by the analysis of plant responses to pathogen infections carried out in natural and controlled environments. Leaf morphological traits, such as hair and stomatal density, were determined for each variety, and the percentage of infected stomata and pathogen colonization of host mesophyll at 24, 48, and 72 hours post inoculation were assessed by epifluorescence microscopy. Furthermore, stilbene production at the site of Plasmopara viticola infection was analyzed at 72 hours post inoculation. Results indicate differences in resistance to downy mildew among selected varieties. Different significant values were detected among grapevines in the percentage of infected stomata and average number of successfully penetrated zoospores per stomata and per leaf surface unit. Differences also emerged in the rate of pathogen growth and stilbene production, signifying that defence mechanisms involved or induced during pathogen infection could be differentially effective among grapevine cultivars in limiting disease progression.

La caracterización molecular y ampelográfica de clones de "Albariño", "Savagnin Blanc" y "Caíño Blanco" (Vitis vinifera L.) demuestra que son cultivares diferentes

The grapevine cultivar "Albariño" is one of the oldest grown in the vine-growing areas of North-Western Spain and Northern Portugal. Since recognition of Origin Denomination status for the Rías Baixas region (the coast of Western Galicia, Spain) in 1987, the economic importance of this cultivar has increased, and its grapes are now among the most expensive in Spain. The area occupied by "Albariño" vines in this region is increasing every year, and the wines made from its grapes are gaining international recognition. These events, plus the fact that "Albariño" was little known outside its traditional growing area, have led to speculation about its origin and the existence of synonyms. Misnames of "Albariño" have included "Savagnin Blanc" and "Caíño Blanco". The present work compares "Albariño", "Savagnin Blanc" and "Caíño Blanco" ampelographically (i.e., it compares shoot, leaf, grape cluster, berry and seed characteristics) and molecularly using microsatellite markers. The results show that they are in fact three different cultivars providing a complete description. For "Caíño Blanco", there is little previously reported information.El "Albariño" es uno de los cultivares más antiguos de la zona vitícola del Noroeste de España y norte de Portugal. Desde la aprobación en el año 1987 de la Denominación de Origen Rías Baixas, este cultivar es el de mayor valor económico de esta zona vitícola, y su uva alcanza uno de los precios más elevados de España. Su superficie de cultivo, dentro de esta Denominación de Origen, se multiplica año tras año, y sus vinos adquieren fama internacional. Todo ello, unido a que era un cultivar poco conocido fuera de esta pequeña zona vitícola española, ha llevado a la aparición en los últimos años de diversas especulaciones sobre su origen, y a la atribución de diferentes sinonimias. Entre los nombres erróneamente atribuidos al "Albariño" se encuentran "Savagnin Blanc" y "Caíño Blanco". En el presente trabajo se hace un estudio comparativo de los tres cultivares a nivel ampelográfico (brote, hoja, racimo, baya, semilla) y a nivel molecular por medio de marcadores microsatélite. Los resultados demuestran que "Albariño", "Savagnin Blanc" y "Caíño Blanco" son cultivares distintos, proporcionando una completa descripción de cada uno. De uno de ellos, "Caíño Blanco", existe muy poca información previa

Variability of the stomata among 'Albariño' (Vitis vinifera L.) clones and its relationship with susceptibility to downy mildew

Research Note

Macro- and microscopic leaf characteristics of six grapevine genotypes (Vitis spp.) with different susceptibilities to grapevine downy mildew

This work reports the leaf morphology of six grapevine genotypes, five belonging to Vitis vinifera and one to Vitis riparia. Earlier studies on these genotypes showed different levels of susceptibility to grapevine downy mildew (Plasmopara viticola). The aim of this work was to detect differences between the leaf morphology of these cultivars at the macro- and microscopic levels, and to characterize morphological traits which could be associated with susceptibility and resistance to downy mildew. An ampelographic description of each genotype was used to develop a scheme illustrating the characteristic leaf morphology. The density and morphology of the trichomes and the stomatal index was assessed by means of microscopical techniques. Distinct macro and microscope differences among the genotypes were seen. No clear relation between ampelographic characteristics and susceptibility to downy mildew was observed. The two cultivars that in earlier studies were found to be the least susceptible to downy mildew were the most similar in terms of their spongy mesophyll. Both showed very little or no wax on the abaxial surface of their leaves.

Estudio para la mejora de la calidad del vino albariño

Premio de Investigación, Real Academia Galega de Ciencias, convocatoria 2009.[EN]Twenty-two clones from Albariño variety (Vitis vinifera L.), from an initial collection of 115 clones, were selected on the basis of their ampelographic, molecular and sanitary characteristics. These selected clones were studied from the agronomic and oenological point of view, and were also quantified for their levels of susceptibility to Powdery Mildew, Oidium and Botrytis. An ecotypic yeast was selected, its use has been patented and it is being exploited. Musts obtained from the previously selected Albariño clones were fermented with this yeast, essentially by increasing the content in volatile substances of interest (terpens: linalool and geraniol; norisoprenoids: α-ionone and β- damascenone), leading to wines with improved fermentative dynamic and sensorial attributes.[ES]En base a características ampelográficas, moleculares y sanitarias, se seleccionaron 22 clones de la variedad Albariño (Vitis vinifera L.), partiendo de 115 iniciales. Sobre los clones seleccionados se ha llevado a cabo un estudio agronómico y enológico, así como la cuantificación de los niveles de susceptibilidad a Mildiu, Oídio y Botrytis. Se ha seleccionado una levadura ecotípica, cuyo uso ha sido patentado y se encuentra en explotación. Con ella se fermentaron los mostos obtenidos a partir de los clones de Albariño previamente seleccionados, dando lugar a vinos con una dinámica fermentativa xPremio de Investigación, Real Academia Galega de Ciencias, convocatoria 2009 y unos atributos sensoriales mejorados, fundamentalmente en base al aumento del contenido en sustancias volátiles de interés (terpenos: linalool y geraniol; norisoprenoides: α-ionona y β- damascenona).La actividad realizada ha sido financiada, además de por la Bodega Terras Gauda S.A., por la Xunta de Galicia (PGIDIT04TAL035E), y por el propio CSIC (PIE 2004 7 0E 214).Peer reviewe

The Level of DING Proteins Is Increased in HIV-Infected Patients: In Vitro and In Vivo Studies

DING proteins constitute an interesting family, owing to their intriguing and important activities. However, after a decade of research, little is known about these proteins. In humans, at least five different DING proteins have been identified, which were implicated in important biological processes and diseases, including HIV. Indeed, recent data from different research groups have highlighted the anti-HIV activity of some DING representatives. These proteins share the ability to inhibit the transcriptional step of HIV-1, a key step of the viral cycle that is not yet targeted by the current therapies. Since such proteins have been isolated from humans, we undertook a comprehensive study that focuses on the relationship between these proteins and HIV-infection in an infectious context. Hence, we developed a home-made ELISA for the quantification of the concentration of DING proteins in human serum. Using this method, we were able to determine the concentration of DING proteins in healthy and HIV-infected patients. Interestingly, we observed a significant increase of the concentration of DING proteins in non treated and treated HIV-infected patients compared to controls. In addition, cell cultures infected with HIV also show an increased expression of DING proteins, ruling out the possible role of antiretroviral treatment in the increase of the expression of DING proteins. In conclusion, results from this study show that the organism reacts to HIV-infection by an overexpression of DING proteins

Deep-sequencing reveals broad subtype-specific HCV resistance mutations associated with treatment failure

A percentage of hepatitis C virus (HCV)-infected patients fail direct acting antiviral (DAA)-based treatment regimens, often because of drug resistance-associated substitutions (RAS). The aim of this study was to characterize the resistance profile of a large cohort of patients failing DAA-based treatments, and investigate the relationship between HCV subtype and failure, as an aid to optimizing management of these patients. A new, standardized HCV-RAS testing protocol based on deep sequencing was designed and applied to 220 previously subtyped samples from patients failing DAA treatment, collected in 39 Spanish hospitals. The majority had received DAA-based interferon (IFN) a-free regimens; 79% had failed sofosbuvir-containing therapy. Genomic regions encoding the nonstructural protein (NS) 3, NS5A, and NS5B (DAA target regions) were analyzed using subtype-specific primers. Viral subtype distribution was as follows: genotype (G) 1, 62.7%; G3a, 21.4%; G4d, 12.3%; G2, 1.8%; and mixed infections 1.8%. Overall, 88.6% of patients carried at least 1 RAS, and 19% carried RAS at frequencies below 20% in the mutant spectrum. There were no differences in RAS selection between treatments with and without ribavirin. Regardless of the treatment received, each HCV subtype showed specific types of RAS. Of note, no RAS were detected in the target proteins of 18.6% of patients failing treatment, and 30.4% of patients had RAS in proteins that were not targets of the inhibitors they received. HCV patients failing DAA therapy showed a high diversity of RAS. Ribavirin use did not influence the type or number of RAS at failure. The subtype-specific pattern of RAS emergence underscores the importance of accurate HCV subtyping. The frequency of “extra-target” RAS suggests the need for RAS screening in all three DAA target regions