Entity

Time filter

Source Type


Pintye A.,Hungarian Academy of Sciences | Bereczky Z.,Hungarian Academy of Sciences | Kovacs G.M.,Eotvos Lorand University | Nagy L.G.,Clark University | And 7 more authors.
Phytopathology | Year: 2012

Pycnidial fungi belonging to the genus Ampelomyces are common intracellular mycoparasites of powdery mildews worldwide. Some strains have already been developed as commercial biocontrol agents (BCAs) of Erysiphe necator and other powdery mildew species infecting important crops. One of the basic, and still debated, questions concerning the tritrophic relationships between host plants, powdery mildew fungi, and Ampelomyces mycoparasites is whether Ampelomyces strains isolated from certain species of the Erysiphales are narrowly specialized to their original mycohosts or are generalist mycoparasites of many powdery mildew fungi. This is also important for the use of Ampelomyces strains as BCAs. To understand this relationship, the nuclear ribosomal DNA internal transcribed spacer (ITS) and partial actin gene (act1) sequences of 55 Ampelomyces strains from E. necator were analyzed together with those of 47 strains isolated from other powdery mildew species. These phylogenetic analyses distinguished five major clades and strains from E. necator that were present in all but one clade. This work was supplemented with the selection of nine inter-simple sequence repeat (ISSR) markers for strain-specific identification of Ampelomyces mycoparasites to monitor the environmental fate of strains applied as BCAs. The genetic distances among strains calculated based on ISSR patterns have also highlighted the genetic diversity of Ampelomyces mycoparasites naturally occurring in grapevine powdery mildew. Overall, this work showed that Ampelomyces strains isolated from E. necator are genetically diverse and there is no indication of strict mycohost associations in these strains. However, these results cannot rule out a certain degree of quantitative association between at least some of the Ampelomyces lineages identified in this work and their original mycohosts. © 2012 The American Phytopathological Society. Source


Zsofi Z.S.,KRC Research Institute for Viticulture and Enology | Toth E.,KRC Research Institute for Viticulture and Enology | Rusjan D.,University of Ljubljana | Balo B.,KRC Research Institute for Viticulture and Enology
Scientia Horticulturae | Year: 2011

Gas-exchange, water relations, vegetative growth and berry sugar concentration of the Kékfrankos grapevine were studied at two growing sites in Eger Wine district, Hungary (Eger-Kölyuktetö - non-stressed, flat vineyard and Eger-Nagyeged hill - water stressed, steep slope vineyard). At the hilly site predawn water potentials and stomatal conductance indicated mild to moderate water stress. As a result, stomatal regulation caused restricted carbon assimilation per unit leaf area. Interestingly, comparing the two sites, lower assimilation rate was accompanied by higher fruit sugar concentration. Water deficit also reduced the yield and the relative proportion of larger berries within bunches. However, in each berry weight category (I: <1. g, II: 1.01-1.25. g, III: 1.26-1.5. g, IV: 1.51-1.75. g, V: 1.76-2. g, VI: >2.01. g) there was a higher sugar concentration at the water stressed vineyard irrespective of berry size. Therefore, berry size was not the only factor that could influence berry sugar concentration. Water deficit also resulted in decreased leaf area per shoot and thus, modification in canopy architecture. Although, there was a higher leaf area for 1. kg fruit at the flat vineyard compared to the hilly site, differences in " sink-source" relations and light interception of the canopy between the sites resulted in different yield sugar concentration. © 2010 Elsevier B.V. Source


Zsofi Z.,KRC Research Institute for Viticulture and Enology | Villango S.,KRC Research Institute for Viticulture and Enology | Palfi Z.,KRC Research Institute for Viticulture and Enology | Palfi X.,KRC Research Institute for Viticulture and Enology
Vitis - Journal of Grapevine Research | Year: 2015

The effect of berry size and moderate water deficit on skin phenolic maturity and berry texture behaviour was studied on Tortugieser' (Vitis vinifera L.) under green house conditions. In all berry weight categories (I: < 1.1 g; II: 1.11-1.4 g; III: 1.41-1.7 g; IV: 1.71-2 g; V: > 2,01 g) water deficit resulted in reduced sugar concentration due to decreased photosynthetic activity. Interestingly, lower phenolic concentration for unit skin mass was measured in the drought stressed treatment compared to the control, irrespective of berry size. However, the concentration of the phenolic components for one berry was lower in the well watered treatment. This phenomenon was due to the increased skin/flesh ratio of the water stressed vines. Berry skin hardness was probably in connection with its phenolic concentration for unit skin weight. Changes in several berry texture parameters were accompanied by changes in berry size. Berry hardness and skin elasticity increased with berry size in both treatments. On the other hand, skin break force, skin break energy, skin thickness showed increase/decrease only in the case of the stressed vines. This result suggests that texture properties of the waterstressed berries depend on berry size to a greater extent compared to the berries of the non-stressed vines. This phenomenon may be explained by the faster ripening of the smaller and of the water stressed berries. © The author(s). Source


Villango S.,KRC Research Institute for Viticulture and Enology | Szekeres A.,University of Szeged | Bencsik O.,University of Szeged | Laposi R.,KRC Research Institute for Viticulture and Enology | And 2 more authors.
Scientia Horticulturae | Year: 2016

The effect of moderate and severe water deficit was examined on berry skin phenolic concentration and composition of the Kékfrankos variety (Vitis vinifera L.). Moderate water stress induced higher concentration of anthocyanin derivatives compared to the non-stressed plants with, the exception of Cya-3-g. Concentrations of some anthocyanin derivatives (Mal-3-g and Peo-3-g) were also higher in the severely stressed berry skins than in the control berries. No differences were found between the stressed and the non-stressed plants in the case of Cya-3-g. Similarly, concentration of some phenolic components (ie. protocatechuic acid, gallic acid, vanillic acid, trans-resveratrol etc.) increased as a result of water deficit. On the other hand, others such as quercetin-3-glucuronide decreased as the water deficit increased. In general, water deficit had a beneficial effect on grape phenolic concentration; however it can be modified by the changes in berry skin/flash ratio. © 2016 Elsevier B.V. Source


Zsofi Z.,KRC Research Institute for Viticulture and Enology | Villango S.,KRC Research Institute for Viticulture and Enology | Palfi Z.,KRC Research Institute for Viticulture and Enology | Toth E.,KRC Research Institute for Viticulture and Enology | Balo B.,KRC Research Institute for Viticulture and Enology
Scientia Horticulturae | Year: 2014

Water deficit has a great impact on grape and wine composition. One aspect of phenolic maturity in red grapevine cultivars is skin phenolic concentration (i.e. anthocyanins). However, extractability of these components is also an important factor during wine making; therefore skin and seed texture properties have a role in this process. Six-year-old Kékfrankos grapevine (Vitis vinifera L.) was submitted to different water regimes (severe, moderate and nil stress) from veraison under greenhouse conditions. Berry quality parameters (sugar and skin phenolic concentration), skin and seed texture properties were measured by a texture analyser at two harvest dates. Water deficit resulted in decreased photosynthetic activity; therefore non-stressed plants produced higher sugar concentration in their berries compared to the stressed vines. Also, water deficit induced increased phenolic concentration in the skin. However, moderate stress treatment showed higher anthocyanin, catechin and total polyphenol concentration than in the severely stressed berries. A significant increase of skin thickness of the stressed berries was observed during ripening; however, no clear relationship was found between skin thickness and its phenolic concentration. Skin break force as well as skin break energy and skin rigidity presented a significant increase as a result of water shortage. No relationship was found between skin thickness and skin hardness. This result suggests that grape skin mechanical properties are dependent on skin structure rather than its thickness. Similarly, there were significant differences among the treatments in seed mechanical properties; however the effect of water stress disappeared by the second harvest. © 2014 Elsevier B.V. Source

Discover hidden collaborations