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 stornata! density, were determined for each variety, and the percentage of infected stornata 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 stornata and average number of successfully penetrated zoospores per stornata 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.Peer reviewe

Evaluación de la sensibilidad en distintas viníferas blancas: mildiu, oídio y botrytis

6 páginas, 6 figuras.--Trabajo publicado en revista de divulgación científica.Peer reviewe

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

In grapevines the stomata are located on the abaxial epidermis of the leaves, arranged in no specific order. As in other plants, they regulate the communication between the internal tissues and the external atmosphere, playing a critical role in both photosynthesis and transpiration processes. Moreover, stomata are the main entrance for pathogens such as Plasmopara viticola (Berk & Curt.)Berl. & de Toni, the causal agent of downy mildew, one of the most widespread fungal diseases of grapevines. Due to this and the fact that downy mildew causes large losses in yield and quality of grapes, there is a great interest to determine the causes of the different degree of susceptibility to this pathogen. Some authors have searched for anatomical features that might be related to the penetration and development of P. viticola in the mesophyll of grapevine leaves, such as the density of leaf hairs (KORTEKAMP and ZYPRIAN, 1999) or the ultrastructure of stomata (JÜRGES et al. 2009). Other authors have examined the differences concerning the number of stomata in different grapevine cultivars (DÜRING 1980, PALLIOTTI et al. 2000, BEN SALEM-FNAYOU et al. 2005), but none had evaluated the differences for this aspect between clones of the same cultivar. Recently some authors have found a strong correlation between the number and size of stomata and the susceptibility to downy mildew (LU et al. 2010). The aim of this work is to determine whether different clones of 'Albariño' differ in terms of their number and size of stomata and its possible relation with the different susceptibility to P. viticola of these same clones.Financial support from the Xunta de Galicia Research Projects (07MRU024403PR).Peer reviewe

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

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). 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.The authors would like to thank Mr. ERIC REMOLIF for grapevine cuttings production, and we gratefully acknowledge the Juana de Vega Foundation (Spain) for its financial support.Fundación Juana de VegaPeer reviewe

Caracterización anatómica e histológica en vid (Vitis vinifera L.). Relación con la resistencia a enfermedades criptogámicas y otros aspectos

1 página.- Artículo publicado en revista de divulgación.Peer reviewe

The effectiveness of stilbenes in resistant Vitaceae: ultrastructural and biochemical events during Plasmopara viticola infection process

Leaves of different Vitis vinifera L. cultivars, susceptible or resistant to downy mildew, Chasselas, Solaris, IRAC 2091 (cvs. Gamaret x Bronner) and Muscadinia rotundifolia were inoculated with Plasmopara viticola. Samples were then examined by scanning and transmission electron microscopy, by light microscopy and for their ability to synthesise stilbenes. These phytoalexins were strictly analysed at infection sites. In the susceptible Chasselas, P. viticola colonises, at 72 h post-infection (hpi), all of the spongy mesophyll with functional haustoria and produces mainly the non toxic piceide. No necrotic zone was observed on Chasselas leaves. The ultrastructural response to downy mildew infection is different in each of the other three resistant grape cultivars. In Solaris, where leaf necrosis are rapidly induced, the infection is restricted to the upper part of the loose spongy mesophyll, and associated with a rapid cell wall disruption and the dispersion of cytoplasmic content along with the production of viniferins. In IRAC 2091, leaf necrosis are quite similar to those observed on Solaris but the infected plant cell, as well as the haustoria, show high electron dense cellular particles without any recognisable organelles, probably related to the effect of the toxic compound pterostilbene, which is synthesised in this grape cultivar. In M. rotundifolia leaf necrosis are much more scarce and smaller than in other cultivars, but pathogen and plant cells are both strongly affected, with concomitant expulsion of cytoplasmic materials through the stomata after P. viticola penetration. In this cultivar, the concentration of all identified stilbenes exceeds 1 × 103 μmol mg−1 FW. The critical role of stilbenes in the resistance of Vitis spp. is discussed.The authors thank Dr. Roger Pezet for critically reading the manuscript, Mr. Eric Remolif for production of grapevine cuttings and Ms. Sevan Kuyumcuyan for helpful technical assistance. We gratefully acknowledge the Juana de Vega Foundation (Spain) for its financial support.Fundación Juana de VegaPeer reviewe

Tinta castañal (Vitis vinifera L.), variedad de interés en las subzona Rosal (D. O. Rías Baixas)

2 páginas, 7 figuras -- Artículo publicado en revista de divulgación.Peer reviewe

The synonym Albarín Blanco (mountain viticulture area) and Blanco Legítimo (coast area). Adaptation due to the origin or clonal variability?

Trabajo presentado en el congreso celebrado en Castiglione di Sicilia, entre el 12 y el 14 de mayo de 2010.Peer Reviewe

Influence of rootstock type on the agronomic characteristics of two grape (Vitis vinifera L.) cultivars grown in the Northwestern Iberian Peninsula

The physiology of grafted plants has been studied by several authors (During, 1994; Ollat et al., 2003) and some rootstock are known to be better than others with respect to the use of water resources and in terms of their adaptation to calcareous soils (Corino and Castino, 1990; Corino et al., 2002). The choice of rootstocks is also important with respect to the resistance against various diseases (Chambre d´Agriculture de L´Aude, 2004; Pinkerton et al., 2005). Several papers have shown that certain agronomic and ampelographic characteristics of vines can change depending on the area of cultivation (Martínez et al., 1997), the weather (Corino and Castino, 1990; Corino et al., 1999), and the rootstock used (Climaco et al., 1999; Corino et al., 1999). The effect of the rootstock on the vegetative growth of the plant, on its fruit production, and on the composition and quality of its wine have been studied for several years (Main et al., 2002; Vanden-Heuvel et al., 2004). Since the effects of a particular rootstock on different cultivars, and the effects of the rootstock in different growing environments have not been elucidated, it is important to know the cultivar-rootstock-environment interactions before any selection is made. Two grape cultivars, Caíño Tinto and Albariño, are widely grown in Galicia (northwestern Spain) and northern Portugal (where they are known as Borraçal and Alvarinho respectively) (Pinto-Carnide et al., 2003; Santiago et al., 2005). Although Albariño is a leading cultivar in this area, their economic interest was only noticiable in the last 20 years and no results have been reported concerning the influence of rootstock type within these two cultivars. Among the rootstocks most commonly used in the study area are those of Vitis berlandieri hybrids. These show high adaptability to saline soils and have good affinity for cultivated grapevines (Hidalgo, 2002). The rootstock 110 Richter is a hybrid between Vitis berlandieri and V. rupestris, while SO4, Selection Oppenheim of Teleki No. 4, is a hybrid between V. berlandieri and V. riparia. Both are commonly used for their ability to adapt to many types of soil and environmental conditions (Reynier, 2002). The aim of the present work was to study the infl uence of rootstock type on a number of production variables in the two grape cultivars.This research has been supported in part by the “Ministerio de Ciencia y Tecnología”, Spain, (VIN00-036-C6-3, RF02-004-C5-2, HP2000-0032, VIN03-002-C6-3). The Excma. Diputación Provincial de Pontevedra also provided a research grant.Peer Reviewe