Investigation of non-structural carbohydrates and xylem anatomy in petiole of grapevine varieties during water limitation and after re-irrigation

Water shortage (WS) during growing of Vitis vinifera L. can limit shoot growth and affect yield and fruit quality, as well as allocation of carbon reserves into perennial organs for the upcoming years. Varietal anatomical differences, such as specific mean xylem vessel diameter in petiole, are expected to influence water transport in canes facing water limitation. Several authors have also evidenced that non-structural carbohydrates (NSC) of adjacent living parenchyma are involved in the repair mechanism of embolized vessels. In this work, we evaluated NSC level and xylem anatomy in petiole of Cabernet Sauvignon and Syrah varieties, subjected to WS and subsequent water refilling in the summer of 2017. The anatomical analysis highlighted that Syrah had high frequency of classes of large vessels, and that the xylem differentiation of vascular bundles was also affected by WS. Moreover, petiole NSC content was significantly influenced by WS and recovery, supporting the hypothesis that starch mobilization was associated to an elevated concentration in soluble NSC. This effect was determinant for Cabernet Sauvignon, whose stress response seemed to be based mainly on NSC metabolism. Finally, Syrah, differently to Cabernet Sauvignon, sustained the WS-induced increase in soluble NSC of petiole also 18 h after re-watering

Analysis of Non-Structural Carbohydrates and Xylem Anatomy of Leaf Petioles Offers New Insights in the Drought Response of Two Grapevine Cultivars

In grapevine, the anatomy of xylem conduits and the non-structural carbohydrates (NSCs) content of the associated living parenchyma are expected to influence water transport under water limitation. In fact, both NSC and xylem features play a role in plant recovery from drought stress. We evaluated these traits in petioles of Cabernet Sauvignon (CS) and Syrah (SY) cultivars during water stress (WS) and recovery. In CS, the stress response was associated to NSC consumption, supporting the hypothesis that starch mobilization is related to an increased supply of maltose and sucrose, putatively involved in drought stress responses at the xylem level. In contrast, in SY, the WS-induced increase in the latter soluble NSCs was maintained even 2 days after re-watering, suggesting a different pattern of utilization of NSC resources. Interestingly, the anatomical analysis revealed that conduits are constitutively wider in SY in well-watered (WW) plants, and that water stress led to the production of narrower conduits only in this cultivar

Insight into Carbohydrate Metabolism and Signaling in Grapevine Buds during Dormancy Progression

Perennial fruit crops enter dormancy to ensure bud tissue survival during winter. However, a faster phenological advancement caused by global warming exposes bud tissue to a higher risk of spring frost damage. Tissue dehydration and soluble sugars accumulation are connected to freezing tolerance, but non-structural carbohydrates also act as metabolic substrates and signaling molecules. A deepened understanding of sugar metabolism in the context of winter freezing resistance is required to gain insight into adaptive possibilities to cope with climate changes. In this study, the soluble sugar content was measured in a cold-tolerant grapevine hybrid throughout the winter season. Moreover, the expression of drought-responsive hexose transporters VvHT1 and VvHT5, raffinose synthase VvRS and grapevine ABA-, Stress- and Ripening protein VvMSA was analyzed. The general increase in sugars in December and January suggests that they can participate in protecting bud tissues against low temperatures. The modulation of VvHT5, VvINV and VvRS appeared consistent with the availability of the different sugar species; challenging results were obtained for VvHT1 and VvMSA, suggesting interesting hypotheses about their role in the sugar–hormone crosstalk. The multifaceted role of sugars on the intricate phenomenon, which is the response of dormant buds to changing temperature, is discussed

Expression patterns of DEMETER-like DNA demethylases homologs hint at potential involvement in grapevine dormancy release

Climate change represents an undeniable threat to traditional viticulture in many areas of the world. Although an increase of average surface temperatures is expected in the future, late frost occurrences are predicted to be an actual challenge, being budburst the critical stage during which cold hardiness levels dramatically decrease and frost vulnerability is at its maximum. Genomic DNA methylation is known as an important mechanism for gene expression regulation. A sub-group of epigenetic regulators named DEMETER-like DNA demethylases (DMLs) has been shown to be involved in budbreak regulation in Populus trichocarpa. In this study, buds of two Vitis cultivars, Fleurtai (Friulano × Kozma 20-3) and UD 31-103 (Merlot × Kozma 20-3), characterized by different levels of resistance to winter freezing temperatures, were sampled during the 2019/2020 winter season. Cold hardiness dynamics were monitored with differential thermal analysis (DTA) at regular intervals. Expression levels of two putative grapevine DEMETER homologs were investigated during natural dormancy conditions. Results show dissimilar deacclimation rates in the two varieties. As observed in other woody species, putative grapevine DEMETERs show downregulation and upregulation trends hinting at a potential involvement in grapevine dormancy release

Insight into Carbohydrate Metabolism and Signaling in Grapevine Buds during Dormancy Progression

Perennial fruit crops enter dormancy to ensure bud tissue survival during winter. However, a faster phenological advancement caused by global warming exposes bud tissue to a higher risk of spring frost damage. Tissue dehydration and soluble sugars accumulation are connected to freezing tolerance, but non-structural carbohydrates also act as metabolic substrates and signaling molecules. A deepened understanding of sugar metabolism in the context of winter freezing resistance is required to gain insight into adaptive possibilities to cope with climate changes. In this study, the soluble sugar content was measured in a cold-tolerant grapevine hybrid throughout the winter season. Moreover, the expression of drought-responsive hexose transporters VvHT1 and VvHT5, raffinose synthase VvRS and grapevine ABA-, Stress- and Ripening protein VvMSA was analyzed. The general increase in sugars in December and January suggests that they can participate in protecting bud tissues against low temperatures. The modulation of VvHT5, VvINV and VvRS appeared consistent with the availability of the different sugar species; challenging results were obtained for VvHT1 and VvMSA, suggesting interesting hypotheses about their role in the sugar–hormone crosstalk. The multifaceted role of sugars on the intricate phenomenon, which is the response of dormant buds to changing temperature, is discussed

Expression of peach sucrose transporters in heterologous systems points out their different physiological role

Sucrose is the major phloem-translocated component in a number of economically important plant species. The comprehension of the mechanisms involved in sucrose transport in peach fruit appears particularly relevant, since the accumulation of this sugar, during ripening, is crucial for the growth and quality of the fruit. Here, we report the functional characterisation and subcellular localisation of three sucrose transporters (PpSUT1, PpSUT2, PpSUT4) in peach, and we formulate novel hypotheses about their role in accumulation of sugar. We provide evidence, about the capability of both PpSUT1 and PpSUT4, expressed in mutant yeast strains to transport sucrose. The functionality of PpSUT1 at the plasma membrane, and of PpSUT4 at the tonoplast, has been demonstrated. On the other hand, the functionality of PpSUT2 was not confirmed: this protein is unable to complement two sucrose uptake-deficient mutant yeast strains. Our results corroborate the hypotheses that PpSUT1 partakes in phloem loading in leaves, and PpSUT4 sustains cell metabolism by regulating sucrose efflux from the vacuole. \ua9 2015 Elsevier Ireland Ltd

Non-structural carbohydrate metabolism in the flesh of Stone fruits of the Genus Prunus (Rosaceae) – a review

Non-structural carbohydrates are abundant constituents of the ripe flesh of all stone fruits. The bulk of their content comprises sucrose, glucose, fructose and sorbitol. However, the abundance of each of these carbohydrates in the flesh differs between species, and also with its stage of development. In this article the import, subcellular compartmentation, contents, metabolism and functions of non-structural carbohydrates in the flesh of commercially cultivated stone fruits of the family Rosaceae are reviewed.Fil: Walker, Robert P. Università degli Studi di Perugia. Dipartimento di Scienze Agrarie, Alimentari e Ambientali; Italia.Fil: Battistelli, Alberto. Consiglio Nazionale delle Ricerche. Istituto di Ricerca sugli Ecosistemi Terrestri; Italia.Fil: Bonghi, Claudio. University of Padova Agripolis. Department of Agronomy, Food, Natural Resources, Animals and Environment; Italy.Fil: Drincovich, María Fabiana. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI -CONICET); Argentina.Fil: Falchi, Rachele. University of Udine. Department of Agricultural, Food, Environmental and Animal Sciences; Italy.Fil: Lara, María V. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI -CONICET); Argentina.Fil: Moscatello, Stefano. Consiglio Nazionale delle Ricerche. Istituto di Ricerca sugli Ecosistemi Terrestri; Italia.Fil: Vizzotto, Giannina. University of Udine. Department of Agricultural, Food, Environmental, and Animal Sciences; Italy.Fil: Famiani, Franco. Università degli Studi di Perugia. Dipartimento di Scienze Agrarie, Alimentari e Ambientali; Italia