Search

Xylem vessels are essential pivotal organs in bulk hydraulic flow through the whole woody plant. However, environmental constraints generate disagreements in xylem structures, which are characterized by air emboli and occlusions formations, compromising water conductivity in grapevines. The aim of this work was to explore xylem morphology dynamics through the xylem sap flow of five Tunisian grapevine cultivars during the natural bleeding sap periods of 2019, 2021, and 2022. In fact, Sakasly, Khamri, Hencha, Razegui1, and Razegui2 rain-fed grapevine cultivars revealed differential responses towards xylem sap movement. The results demonstrated that the xylem sap flow was significantly more abundant in 2019 than 2021 and 2022 bleeding sap campaigns. A variation was revealed between the cultivars regarding the xylem sap flow. In fact, Sakasly gave the best xylem flow during the three campaigns. Razegui1 and Razegui2 registered approximately similar xylem sap flow, while Hencha and Khamri present the lowest sap fluxes during the three campaigns. Moreover, several vascular occlusions forms were identified from stem cross sections using environmental scanning electron microscopy (ESEM), including tyloses, gels, starch, and gum deposits. The highest occlusion number was observed in Sakasly, Razegui1, and Razegui2 cultivars. Among different biogenic calcium shapes, several were observed for the first time in grapevine, including multi-faceted druse, cubic, crystalline sand, styloids, spherical, or drop-like structures. Considering their lower flow and totally blocked vessels, both Hencha and Khamri confirmed their susceptibility to environmental constraints. However, Sakasly, Razegui1, and Razegui2 cultivars presented higher tolerance according to their sap flow and xylem morphology. [ABSTRACT FROM AUTHOR]

Salinity is one of the most common environmental stresses affecting grapevine productivity. In order to analyze the contribution of the dehydration-responsive RD22 gene of Vitis vinifera L. (VvRD22) to salt tolerance improvement, Agrobacterium-mediated transformation in the tobacco model plant (Nicotiana benthamiana) was carried out and transgenic lines were subjected to in vitro and ex vitro salt treatments for physiological response evaluation. Under in vitro salt stress, the transgenic lines exhibited higher seed germination and growth than the wild type (WT). The ex vitro assays after salt treatment showed better growth and higher chlorophyll content in VvRD22-expressing plants than in the WT. Ion analysis revealed less increase in the levels of sodium (Na+) in leaves and chloride (Cl-) in all organs within the transgenic lines compared to the WT. Interestingly, stabilized calcium (Ca2+) contents were registered in the leaves of transgenic lines. Moreover, the occurrence of an osmotic adjustment based on an overproduction of total soluble sugars was observed within the transgenic lines. These physiological responses suggest that the protective effect of VvRD22 transgenic expression is enabling other physiological mechanisms to function and subsequently contributing to the ability to cope with salt stress. The VvRD22 transgenic expression would be useful in engineering salt stress-tolerant grapevines. [ABSTRACT FROM AUTHOR]

Highlights: [•] We assessed population structure in Tunisian Vitis sylvestris using SSRs. [•] Genetic and demographic data highlighted high extinction level within this flora. [•] Various conservation plans were suggested for best management of grapevine. [Copyright &y& Elsevier]

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An efficient protein extraction method is crucial to ensure successful separation by two-dimensional electrophoresis (2-DE) for recalcitrant plant species, in particular for grapevine ( Vitis vinifera L.). Trichloroacetic acid-acetone (TCA-acetone) and phenol extraction methods were evaluated for proteome analysis of leaves and roots from the Tunisian cultivar 'Razegui'. The phenol-based protocol proved to give a higher protein yield, a greater spot resolution, and a minimal streaking on 2-DE gels for both leaf and root tissues compared with the TCA-based protocol. Furthermore, the highest numbers of detected proteins on 2-DE gels were observed using the phenol extraction from leaves and roots as compared with TCA-acetone extraction. [ABSTRACT FROM AUTHOR]

The constitutive expression of a Vitis vinifera dehydrin ( DHN ) of the YSK 2 type ( VvDhn ) allowed for a more vigorous growth in transgenic tobacco plants than in wild-type (WT). In vitro , a very distinct germination kinetics and root development profile was observed both under optimal and stress conditions (control, mannitol, NaCl). Transgenic lines outperformed WT in germination success and precocity and root length. Furthermore, transgenic lines were able to germinate under 300 mM mannitol. Adult tobacco plants expressing VvDhn also displayed improved tolerance to both drought and salt stresses. The VvDhn lines under these constraints were significantly better than WT in terms of biomass and leaf number. Moreover, higher capacities to recover from drought were revealed. However, the major effect the VvDhn over-expression was observed under non limiting conditions. VvDhn interfered with the development program leading to higher biomass production (leaf, shoot and root) and to the production of higher number of leaves. The VvDhn gene show great promise for grapevine genetic improvement to drought and salinity tolerance. VvDhn gene can be used to screen and/or design for new grapevine rootstocks that together with viticultural management programs has the potential to cope successfully with a more adverse and unpredictable climate, which is highly demand by community. [ABSTRACT FROM AUTHOR]

Abstract: Salt stress adversely affects the growth of grapevine plants. In order to understand the molecular basis of salt stress response in grapevine plants, suppression subtractive hybridization (SSH) and microarray based screening approaches were combined. Two leaf-specific subtractive cDNA libraries were constructed from grapevine plants subjected to a moderate, incremental salt stress treatment. SSH were performed 6h and 24h after NaCl peaked at 100mM using cDNAs prepared from leaves of a salt tolerant cultivar (Razegui) as testers and cDNAs from unstressed leaves as drivers. Then, a pre-screened subset of cDNA clones from these SSH libraries were used to construct a Vitis vinifera cDNA array, in order to verify the expression changes of the genes upon salt treatment. Expression profiles were compared between the salt tolerant and a susceptible cultivar (Syrah) under both control conditions and after salt stress treatment. Seven cDNA clones were identified which were up-regulated by salt stress in two independent growth experiments and confirmed by RNA blot analysis. The transcript expression patterns of the selected genes differed between the contrasting grapevine cultivars tested with respect to stress-regulation. The possible relationship of individual cDNAs with salinity tolerance mechanisms is discussed. [Copyright &y& Elsevier]

The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the field. Pro-embryogenic calluses were induced on Chùe and Pool (1987) basal medium, supplemented with 9 μM of 2,4-dichlorophenoxyacetic acid (2,4-D) and 11.35 μM of thidiazuron (TDZ) under dark conditions. Different anther zones (filament, abaxial, adaxial, lateral zones and entire anthers) were involved in somatic embryogenesis induction. The percentages of granular and yellowish pro-embryogenic call uses ranged between 15.6% and 34.8% in 'Kahli Kerkennah' and 'Muscat Raf-raf' cultivars, respectively. Although, morphological diversifications of pro-embryogenic calluses (several necrosis and spontaneous maturation) were observed on the induction medium after 5 subcultures. The reduction of 2,4-D and TDZ levels to 4.52 μM and 2.89 μM respectively, induced granular and yellowish embryogenic material. Thus, Chée and Pool (1987) (CP) enriched with 4.52 μM of 2,4-D and 2.89 μM of TDZ revealed to be the most appropriate for long-term maintenance. In fact, all the cultivars presented high and regular embryo maturation rates after 12, 24, 36 and 48 months of cultivation on this medium, under light conditions. After 4 years, they still exhibit high germination and regeneration abilities. Germination of somatic embryos was achieved on Murashige and Skoog (1962) basal-medium, with rates ranging from 69% to 96%. Only 5% of somatic embryos were concerned by morphological variations. The regenerated plantlets presented a normal phenotype under controlled greenhouse conditions, compared to mother plants. [ABSTRACT FROM AUTHOR]