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Northeastern part of Turkey is rich in terms of autochthonous grape cultivars. In the region Yusufeli district has special importance for historical cultivation of grapevine. This small district has over fourteen local grape cultivars. Present study describe morphological and biochemical characteristics of nine autochthonous grape cultivars grown in Yusufeli district in Turkey. The standard Turkish grape cultivar 'Cavus' was also included experiment to make comparison with local ones. Bunch size, berry color, berry shape and usage are the searched main morphological characteristics. Phenolic compounds, organic acids, vitamin C and specific sugars were the main biochemical parameters. We found a wide variation among both morphological and biochemical characteristics. The cultivars showed low to medium bunch size. Chlorgenic acid (2.231–4.811 mg/L), syringic acid (1.027–5.426 mg/L) and rutin (1.013–1.129 mg/L) were found the highest content in berries of cultivars. As expected, tartaric acid that characteristic for grape berries was the dominant (ranged from 1.826 to 3.336 g/L) and followed by malic acid (ranged from 1.089 to 2.344 g/L). The all autochthonous grape cultivars had glucose the highest concentration as major sugar and followed by fructose. It can be concluded that morphological and biochemical characteristics analyzed could be useful to give information about selection of the promising grape cultivars for breeders. [ABSTRACT FROM AUTHOR]

Plant NHX antiporters are critical for cellular pH, Na+, and K+ homeostasis and salt tolerance. Even though their genomic and functional studies have been conducted in many species, the grapevine NHX family has not been described yet. Our work highlights the presence of six VvNHX genes whose phylogenetic analysis revealed their classification in two distinct groups: group I vacuolar (VvNHX1–5) and group II endosomal (VvNHX6). Several cis-acting regulatory elements related to tissue-specific expression, transcription factor binding, abiotic/biotic stresses response, and light regulation elements were identified in their promoter. Expression profile analyses of VvNHX genes showed variable transcription within organs and tissues with diverse patterns according to biochemical, environmental, and biotic treatments. All VvNHXs are involved in berry growth, except VvNHX5 that seems to be rather implicated in seed maturation. VvNHX4 would be more involved in floral development, while VvNHX2 and 3 display redundant roles. QPCR expression analyses of VvNHX1 showed its induction by NaCl and KNO3 treatments, whereas VvNHX6 was induced by ABA application and strongly repressed by PEG treatment. VvNHX1 plays a crucial role in a bunch of grape developmental steps and adaptation responses through mechanisms of phyto-hormonal signaling. Overall, VvNHX family members could be valuable candidate genes for grapevine improvement. [ABSTRACT FROM AUTHOR]

Plant NHX antiporters are responsible for monovalent cation/H+ exchange across cellular membranes and play therefore a critical role for cellular pH regulation, Na+ and K+ homeostasis, and salt tolerance. Six members of grapevine NHX family (VvNHX1-6) have been structurally characterized. Phylogenetic analysis revealed their organization in two groups: VvNHX1-5 belonging to group I (vacuolar) and VvNHX6 belonging to group II (endosomal). Conserved domain analysis of these VvNHXs indicates the presence of different kinds of domains. Out of these, two domains function as monovalent cation-proton antiporters and one as the aspartate-alanine exchange; the remaining are not yet with defined function. Overall, VvNHXs proteins are typically made of 11-13 putative transmembrane regions at their N-terminus which contain the consensus amiloride-binding domain in the 3rd TM domain and a cation-binding site in between the 5th and 6th TM domain, followed by a hydrophilic C-terminus that is the target of several and diverse regulatory posttranslational modifications. Using a combination of primary structure analysis, secondary structure alignments, and the tertiary structural models, the VvNHXs revealed mainly 18 α helices although without β sheets. Homology modeling of the 3D structure showed that VvNHX antiporters are similar to the bacterial sodium proton antiporters MjNhaP1 (Methanocaldococcus jannaschii) and PaNhaP (Pyrococcus abyssi). [ABSTRACT FROM AUTHOR]

Our study aims to assess the implication of WRKY transcription factor in the molecular mechanisms of grapevine adaptation to salt and water stresses. In this respect, a full-length VvWRKY2 cDNA, isolated from a Vitis vinifera grape berry cDNA library, was constitutively over-expressed in Nicotiana tabacum seedlings. Our results showed that transgenic tobacco plants exhibited higher seed germination rates and better growth, under both salt and osmotic stress treatments, when compared to wild type plants. Furthermore, our analyses demonstrated that, under stress conditions, transgenic plants accumulated more osmolytes, such as soluble sugars and free proline, while no changes were observed regarding electrolyte leakage, H2O2, and malondialdehyde contents. The improvement of osmotic adjustment may be an important mechanism underlying the role of VvWRKY2 in promoting tolerance and adaptation to abiotic stresses. Principal component analysis of our results highlighted a clear partition of plant response to stress. On the other hand, we observed a significant adaptation behaviour response for transgenic lines under stress. Taken together, all our findings suggest that over-expression of VvWRKY2 gene has a compelling role in abiotic stress tolerance and, therefore, would provide a useful strategy to promote abiotic stress tolerance in grape via molecular-assisted breeding and/or new biotechnology tools. [ABSTRACT FROM AUTHOR]