Effects of Wind Exposure and Deficit Irrigation on Vegetative Growth, Yield Components and Berry Composition of Malbec and Cabernet Sauvignon.

The impact of global warming on Argentine viticulture may result in a geographical shift, with wine-growing regions potentially moving towards the southwest, known as one of the windiest regions in the world. Deficit irrigation is a widely used strategy to control the shoot growth and improve fruit quality attributes, such as berry skin polyphenols. The present study aimed to assess the effects of different wind intensities and irrigation levels, as well as their interactions, on field-grown Vitis vinifera L. cvs. Malbec and Cabernet Sauvignon. The experiment was conducted during two growing seasons with two wind treatments (sheltered and exposed) and two irrigation treatments (well-watered and moderate deficit irrigation) in a multifactorial design. Vegetative growth, stomatal conductance, shoot biomass partition, fruit yield components and berry skin phenolics were evaluated. Our study found that, generally, wind exposure reduced vegetative growth, and deficit irrigation increased the proportion of smaller berries within the bunches. Meanwhile, deficit irrigation and wind exposure additively increased the concentration of berry skin phenolics. Combined stressful conditions enhance biomass partition across the shoot to fruits in Malbec, increasing the weight of bunches and the number of berries. Our findings offer practical implications for vineyard managers in windy regions, providing actionable insights to optimize grapevine cultivation and enhance wine quality.

Phenolic, Nutritional and Sensory Characteristics of Bakery Foods Formulated with Grape Pomace.

The potentiality of cv. Malbec grape pomace (GP) as a functional ingredient in the formulation of bakery foods (muffins, biscuits and cereal bars) was studied. The effect of GP addition on the phenolic compounds (PCs) composition, nutritional and sensory properties were evaluated. The addition of GP increased the content of dietary fiber, proteins, ash, total phenolic content (TPC), antiradical capacity (AC), anthocyanins and non-anthocyanin PCs while decreasing the carbohydrates content. The main PCs given by the GP to supplemented foods were quercetin-3-O-glucoside, rutin, caffeic acid, syringic acid and (+)-catechin. For anthocyanins, the acylated derivatives were more stable to heat treatment (baking) in food processing which was evidenced by a higher proportion of these PCs compounds when compared to the same derivatives quantified in GP. In general, when the TPC or individual concentrations of PCs were analyzed in a nutritional or functional context, one portion of the supplemented foods showed levels high enough to satisfy the recommended dose per day of these bioactive compounds. Additionally, the foods were well received by consumers during the sensory evaluation and supplemented biscuits received the highest acceptability. This study demonstrated that GP could be a viable functional ingredient in bakery foods to incorporate components like PCs and dietary fiber into traditional consumers' diets.

Climate Change Effects on Grapevine Physiology and Biochemistry: Benefits and Challenges of High Altitude as an Adaptation Strategy.

Grapevine berry quality for winemaking depends on complex and dynamic relationships between the plant and the environment. Winemakers around the world are demanding a better understanding of the factors that influence berry growth and development. In the last decades, an increment in air temperature, CO2 concentration and dryness occurred in wine-producing regions, affecting the physiology and the biochemistry of grapevines, and by consequence the berry quality. The scientific community mostly agrees in a further raise as a result of climate change during the rest of the century. As a consequence, areas most suitable for viticulture are likely to shift into higher altitudes where mean temperatures are suitable for grape cultivation. High altitude can be defined as the minimum altitude at which the grapevine growth and development are differentially affected. At these high altitudes, the environments are characterized by high thermal amplitudes and great solar radiations, especially ultraviolet-B (UV-B). This review summarizes the environmental contribution of global high altitude-related climatic variables to the grapevine physiology and wine composition, for a better evaluation of the possible establishment of vineyards at high altitude in climate change scenarios.

Halotolerant native bacteria Enterobacter 64S1 and Pseudomonas 42P4 alleviate saline stress in tomato plants.

Salinity is one of the principal abiotic stresses that limit the growth and productivity of crops. The use of halotolerant plant growth-promoting rhizobacteria (PGPR) that increase the growth of salt-stressed crops is an environmentally friendly alternative to promote plant yield under salinity. The aim of this study was to test native PGPR, isolated according to their tolerance to NaCl, and to evaluate their influence on morphological, physiological, and biochemical traits promoted by salt stress in tomato plants. Enterobacter 64S1 and Pseudomonas 42P4 were selected as the most efficient strains in terms of salt tolerance. Both strains were classified as moderately resistant to salinity (NaCl) and maintained their plant growth-promoting activities, such as nitrogen fixation and phosphate solubilization, even in the presence of high levels of salt. The results of a greenhouse experiment demonstrated that PGPR inoculation increased root and shoot dry weight, stem diameter, plant height, and leaf area compared to control noninoculated plants under nonsaline stress conditions, reversing the effects of salinity. Inoculated plants showed increased tolerance to salt conditions by reducing electrolyte leakage (improved membrane stability) and lipid peroxidation and increasing chlorophyll quantum efficiency (Fv/Fm) and the performance index. Also, inoculation increased the accumulation of proline and antioxidant nonenzymatic compounds, such as carotenes and total phenolic compounds. The catalase and peroxidase activities increased with salinity, but the effect was reversed by Enterobacter 64S1. In conclusion, Enterobacter 64S1 and Pseudomonas 42P4 isolated from salt-affected regions have the potential to alleviate the deleterious effects of salt stress in tomato crops.

Abscisic Acid's Role in the Modulation of Compounds that Contribute to Wine Quality.

Abscisic acid (ABA) plays a crucial role in the plant responses to environmental signals, in particular by triggering secondary metabolism. High-altitude vineyards in Mendoza, Argentina, are exposed to elevated solar ultraviolet-B (UV-B) levels and moderate water deficits (WD), thus producing grapevine berries with high enological quality for red winemaking. Volatile organic compounds (VOCs) and phenolic compounds (PCs) accumulate in the berry skins, possess antioxidant activity, and are important attributes for red wine. The aim of the present study was to analyze the role of ABA in the modulation of these compounds in Vitis vinifera L. cv. Malbec wines by comparing the independent and interactive effects of UV-B, WD, and ABA. Two UV-B treatments (ambient solar UV-B or reduced UV-B), two watering treatments (well-watered or moderate water deficit) and two ABA treatments (no ABA and sprayed ABA) were given in a factorial design during one growing season. Sprayed ABA, alone and/or in combination with UV-B (specially) and WD (to a lower degree) increased low molecular weight polyphenols (LMWP), anthocyanins, but most noticeably the stilbenes trans-resveratrol and piceid. Under these treatments, VOCs were scarcely affected, and the antioxidant capacity was influenced by the combination of UV-B and WD. From a technological point of view, ABA applications may be an effective vineyard management tool, considering that it elicited a higher content of compounds beneficial for wine aging, as well compounds related to color.

Non-structural carbohydrates and sugar export in grapevine leaves exposed to different light regimes.

Light is a main environmental factor that determines leaf microclimate within the vine, as well as its photosynthesis and carbohydrate metabolism. This study aimed to examine the relationships between photosynthesis, carbohydrate metabolism, and the expression of related genes in leaves of grapevine grown under different radiation regimes. During the 2014/2015 growing season, an experiment was conducted on a Malbec vineyard (Vitis vinifera L.) in which four radiation exposure treatments were established on the leaves: (1) East, (2) West, (3) Sun, and (4) Shade (i.e., reduction in light intensity). Diurnal dynamics of photosynthesis and non-structural carbohydrates were measured and leaf export rates were calculated. Transcript profiles of leaf sugar transporters (VvHT1, VvHT3, VvSUC27), a sucrose phosphate synthase enzyme (VvSPS), and invertases (VvGIN1, VvCWI) were also examined. We showed that East and Sun leaves had higher daily photosynthetic and export rates than West leaves, which was mainly explained by the environmental conditions (air and leaf temperature, VPDleaf-air ) and leaf water status. Shade leaves accumulated less starch and soluble sugars than exposed leaves, which correlated with a higher expression of hexose transporters and invertases. The hypotheses that these sugars in Shade leaves would play a role as signaling molecules and/or have increased sink strength and phloem unloading are discussed. These results allow us to understand the physiological and molecular behavior of leaves exposed to different radiation regimes, which can be used to design appropriate vineyard management practices.

Native bacteria isolated from roots and rhizosphere of Solanum lycopersicum L. increase tomato seedling growth under a reduced fertilization regime.

In semiarid regions is important to use native strains best adapted to these environments to optimize plant-PGPR interaction. We aimed to isolate and characterize PGPR from roots and rhizosphere of a tomato crop, as well as studying the effect of its inoculation on tomato seedlings growth. We selected four strains considering their effectiveness of fixing nitrogen, solubilizing phosphate, producing siderophores and indole acetic acid. They belong to the genera Enterobacter, Pseudomonas, Cellulosimicrobium, and Ochrobactrum. In addition, we also analyzed the ability to solubilize Ca3(PO4)2, FePO4 and AlPO4 and the presence of one of the genes encoding the cofactor PQQ in their genome. Enterobacter 64S1 and Pseudomonas 42P4 showed the highest phosphorus solubilizing activity and presence of pqqE gene. Furthermore, in a tomato-based bioassay in speed-bed demonstrated that a sole inoculation at seedling stage with the strains increased dry weight of roots (49-88%) and shoots (39-55%), stem height (8-13%) and diameter (5-8%) and leaf area (22-31%) and were equal or even higher than fertilization treatment. Leaf nitrogen and chlorophyll levels were also increased (50-80% and 26-33%) compared to control. These results suggest that Enterobacter 64S1 and Pseudomonas 42P4 can be used as bio-inoculant in order to realize a nutrient integrated management.

Variation in the amino acids, volatile organic compounds and terpenes profiles in induced polyploids and in Solanum tuberosum varieties.

Polyploids often display a variety of phenotypic novelties when compared to their diploid progenitors, some of which may represent ecological advantages, especially regarding tolerance to biotic and abiotic factors. Plants cope with environmental factors by producing chemicals such as volatile organic compounds (VOCs) and specific amino acids (AAs). In potato, the third most important food crop in the world, gene introgression from diploid wild relative species into the genetic pool of the cultivated species (tetraploid) would be of great agronomical interest. The consequences of allopolyploidization on the potato VOCs and AAs profiles have not been yet analyzed. In this work, the effects of whole genome duplication on VOCs and AAs contents in leaves of potato allo- and autotetraploids and cultivated varieties were studied. The polyploids were obtained by chromosomal duplication of a genotype of the wild diploid species S. kurtzianum (autopolyploid model), and a diploid interspecific hybrid between the cultivated species S. tuberosum and S. kurtzianum (allopolyploid model). Almost all compounds levels varied greatly among these tetraploid lines; while all tetraploids showed higher contents of non-isoprenoids compounds than diploids, we found either increments or reductions in terpenes and AAs content. The results support the idea that genome duplication is a stochastic source of variability, which might be directly used for introgression in the 4x gene pool of the cultivated potato by sexual hybridization.

Modeling vegetative vigour in grapevine: unraveling underlying mechanisms.

Mechanistic modeling constitutes a powerful tool to unravel complex biological phenomena. This study describes the construction of a mechanistic, dynamic model for grapevine plant growth and canopy biomass (vigor). To parametrize and validate the model, the progeny from a cross of Ramsey (Vitis champinii) × Riparia Gloire (V. riparia) was evaluated. Plants with different vigor were grown in a greenhouse during the summer of 2014 and 2015. One set of plants was grafted with Cabernet Sauvignon. Shoot growth rate (b), leaf area (LA), dry biomass, whole plant and root specific hydraulic conductance (kH and Lpr), stomatal conductance (gs), and water potential (Ψ) were measured. Partitioning indices and specific leaf area (SLA) were calculated. The model includes an empirical fit of a purported seasonal pattern of bioactive GAs based on published seasonal evolutionary levels and reference values. The model provided a good fit of the experimental data, with R = 0.85. Simulation of single trait variations defined the individual effect of each variable on vigor determination. The model predicts, with acceptable accuracy, the vigor of a young plant through the measurement of Lpr and SLA. The model also permits further understanding of the functional traits that govern vigor, and, ultimately, could be considered useful for growers, breeders and those studying climate change.

Olive oil characterization of cv. 'Arauco' harvested at different times in areas with early frost in Mendoza, Argentina.

BACKGROUND: 'Arauco' is the only autochthonous olive cultivar from Argentina. Little has been reported so far regarding the management of this crop. In this work, variations in fruit and chemical characteristics of olives harvested over a wide range of dates and seasons are reported for this cultivar at two sites in Mendoza province in central west Argentina. RESULTS: During the harvest periods studied, fruit oil content on a dry basis remained at its maximum and was stable, but fruit oil content on fresh basis increased as water content decreased with delay in harvest date. Harvest date affected the maturity index of fruits as well as the oxidative stability and phenolic content of oil. In contrast, the fatty acid profile was not consistently affected by harvest date. Environmental conditions, mainly the occurrence and intensity of frosts, strongly influenced oil quality as well as maturity with delay in harvest date. CONCLUSION: The most appropriate harvest time to obtain Arauco oil with a high oil yield and good chemical quality was before mid-May and with maturity index lower than 2. Fruits harvested after mid-May were exposed to minimum temperatures between -1.2 °C and - 4.0 °C, producing oil with low phenolic compounds and oxidative stability. © 2019 Society of Chemical Industry.

Phenolic metabolites in plasma and tissues of rats fed with a grape pomace extract as assessed by liquid chromatography-tandem mass spectrometry.

Grape pomace extract (GPE) is a rich and relatively low-cost source of phenolic compounds. However, little is known about the main GPE metabolites in mammals, which could help explain the observed health-promoting effects. This study investigated the presence of parent compounds from flavanol, flavonol and stilbene families and their metabolites in rat plasma and tissues after an acute intake of GPE in doses of 300 and 600 mg kg/body weight. The measurement of free compounds and their metabolites was performed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Results showed the presence of epicatechin, epicatechin methyl-glucuronide, epicatechin methyl-sulphate, catechin, catechin-glucuronide, quercetin methyl-glucuronide, resveratrol-3-glucuronide, resveratrol-4-glucuronide and resveratrol-3-sulphate in plasma, which was dose dependent. The most abundant measured compound in plasma was epicatechin-glucuronide. The presence of glucuronidated and methyl-glucuronidated forms of catechin were observed in the liver at both doses, while epicatechin-glucuronide and methyl-glucuronide were detected only upon intake of 600 mg GPE/kg body weight. At this dose epicatechin-glucuronide and methyl-glucuronide were also detected in muscle, and catechin methyl-glucuronide in adipose tissue. Results show the main GPE metabolites present in rat tissues after oral consumption, contributing to better understand the health benefits of GPE and its potential utilization as a functional ingredient.

Arsenic and trace elements in soil, water, grapevine and onion in Jáchal, Argentina.

Contamination by trace elements (TE) is an increasing concern worldwide. In some areas, crop production could be limited by the presence of metals and metalloids, so it is important to determine their concentrations and mobility. The region of Jáchal, province of San Juan, Argentina, has good growing conditions for onion and grapevine production, but their quality and yield are affected by high TE concentration in soils and water. Soils, water, grapevine and onion were sampled and TE content determined. In soils elevated As, B, Cr, Hg, and Tl concentrations were detected (506±46, 149±3, 2714±217, 16±7, and 12±3µgg-1, respectively, for maximum values measured), and physicochemical properties of the soil promotes these elements mobility. Water samples had high As, B, Cr, and Fe concentrations (1438±400, 10,871±471, 11,516±2363, and 3071±257µgL-1, respectively, for maximum values measured) while in onion bulbs and grapevine berries, As, Cr, Cu, and Fe (92±7 and 171±20, 1412±18 and 2965±32, 17±3 and 126±88, and 418±204 and 377±213µgg-1, respectively, for maximum values measured) exceeded the limits for food consumption established by Argentinian law. Correlation analyses indicated that: i) there is a common source of TE in this area, ii) each elements concentration in plants is associated with different soil variables and different soils depths, and iii) the lack of correlation between soil and water indicates that concentration in water is not constant over the time and/or there exists a differential accumulation of elements in soils depending on their own properties. Data obtained demonstrate very high concentration of TE in soil, grapevines, and onion plants in Jáchal region, and different remediation techniques are necessary to stabilize and minimize the bioavailability of these elements.

Grape pomace reduced reperfusion arrhythmias in rats with a high-fat-fructose diet.

Metabolic syndrome (MetS) is a risk factor for sudden cardiac death in humans, but animal models are needed for the study of this association. Grape pomace (GP), obtained from the winemaking process, contains phenolic compounds with potential cardioprotective effects. The aim of this study was to evaluate if a high-fat-fructose (HFF) diet facilitates the occurrence of arrhythmias during the reperfusion, and if a GP supplementation could counteract these effects. Wistar rats were fed with control (Ctrl), HFF diet and HFF plus GP (1 g kg-1 day-1) for six weeks. The HFF diet induces characteristic features of MetS (higher systolic blood pressure, dyslipidemia and insulin resistance) which was attenuated by GP supplementation. In addition, HFF induced increased reperfusion arrhythmias that were reduced upon GP supplementation. GP also reduced the non-phosphorylated form of connexin-43 (Cx43) while enhancing heart p-AKT and p-eNOS protein levels and reducing Nox4 levels enhanced by the HFF diet, indicating that GP may increase NO bioavailability in the heart. We found a murine model of MetS with increased arrhythmogenesis and translational value. Furthermore, GP prevents diet-induced heart dysfunction and metabolic alterations. These results highlight the potential utilization of winemaking by-products containing significant amounts of bioactive compounds to prevent/attenuate MetS-associated cardiovascular pathologies.

Bacteria and smoke-water extract improve growth and induce the synthesis of volatile defense mechanisms in Vitis vinifera L.

Sustainable agricultural practices have been developed as alternative to the use of agrochemicals, and viticulture is not exempt of that. Plant growth promoting rhizobacteria (PGPR) and smoke water extracts (SW) are environmentally-friendly alternative to those agrochemicals. The aim of this study was to investigate the single or combined effects of SW and the PGPR Pseudomonas fluorescens (Pf) and Bacillus licheniformis (Bl) on the physiology and biochemistry of grapevines plants. After 38 days, single applications of SW solutions and bacterial suspensions increase rooting and root length. Combined treatments had a slight positive effect compared to the water control. At the end of 60-days pot trial, grapevine treated with 1:1000 SW and Pf applied alone showed increases in stem length, leaf area and fresh weight of the roots, shoot and leaves, although not significantly differences from the water control were found. In addition, Pf augmented chlorophyll relative content, all treatments decreased the stomatal conductance (mainly 1:500 SW, Pf and 1:1000 SW + Bl), as well as lipid peroxidation in roots (mainly in bacterial treatments), and induced the synthesis of mono and sesquiterpenes in leaves, where the effect was enhanced in combined treatments. In conclusion, PGPR and SW are effective to improve growth of V. vinifera cuttings as well as to increase the plants defense mechanisms that may help them to cope with biotic and abiotic stresses.

Grapevine tissues and phenology differentially affect soluble carbohydrates determination by capillary electrophoresis.

Soluble carbohydrates distribution depends on plant physiology and, among other important factors, determines fruit yield and quality. In plant biology, the analysis of sugars is useful for many purposes, including metabolic studies. Capillary electrophoresis (CE) proved to be a powerful green separation technique with minimal sample preparation, even in complex plant tissues, that can provide high-resolution efficiency. Matrix effect refers to alterations in the analytical response caused by components of a sample other than the analyte of interest. Thus, the assessment and reduction of the matrix factor is fundamental for metabolic studies in different matrices. The present study evaluated the source and levels of matrix effects in the determination of most abundant sugars in grapevine tissues (mature and young leaves, berries and roots) at two phenological growth stages. Sucrose was the sugar that showed the least matrix effects, while fructose was the most affected analyte. Based on plant tissues, young leaves presented the smaller matrix effects, irrespectively of the phenology. These changes may be attributed to considerable differences at chemical composition of grapevine tissues with plant development. Therefore, matrix effect should be an important concern for plant metabolomics.

ABA and GA3 regulate the synthesis of primary and secondary metabolites related to alleviation from biotic and abiotic stresses in grapevine.

Plants are able to synthesize a large number of organic compounds. Among them, primary metabolites are known to participate in plant growth and development, whereas secondary metabolites are mostly involved in defense and other facultative processes. In grapevine, one of the major fruit crops in the world, secondary metabolites, mainly polyphenols, are of great interest for the wine industry. Even though there is an extensive literature on the content and profile of those compounds in berries, scarce or no information is available regarding polyphenols in other organs. In addition, little is known about the effect of plant growth regulators (PGRs), ABA and GA3 (extensively used in table grapes) on the synthesis of primary and secondary metabolites in wine grapes. In table grapes, cultural practices include the use of GA3 sprays shortly before veraison, to increase berry and bunch size, and sugar content in fruits. Meanwhile, ABA applications to the berries on pre-veraison improve the skin coloring and sugar accumulation, anticipating the onset of veraison. Accordingly, the aim of this study was to assess and characterize primary and secondary metabolites in leaves, berries and roots of grapevine plants cv. Malbec at veraison, and changes in compositions after ABA and GA3 aerial sprayings. Metabolic profiling was conducted using GC-MS, GC-FID and HPLC-MWD. A large set of metabolites was identified: sugars, alditols, organic acids, amino acids, polyphenols (flavonoids and non-flavonoids) and terpenes (mono-, sesqui-, di- and triterpenes). The obtained results showed that ABA applications elicited synthesis of mono- and sesquiterpenes in all assessed tissues, as well as L-proline, acidic amino acids and anthocyanins in leaves. Additionally, applications with GA3 elicited synthesis of L-proline in berries, and mono- and sesquiterpenes in all the tissues. However, treatment with GA3 seemed to block polyphenol synthesis, mainly in berries. In conclusion, ABA and GA3 applications to grapevine plants cv. Malbec influenced the synthesis of primary and secondary metabolites known to be essential for coping with biotic and abiotic stresses.

Malbec grape (Vitis vinifera L.) responses to the environment: Berry phenolics as influenced by solar UV-B, water deficit and sprayed abscisic acid.

High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and -UV-B), watering (+D and -D) and ABA (+ABA and -ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity.

Rhizosphere associated bacteria trigger accumulation of terpenes in leaves of Vitis vinifera L. cv. Malbec that protect cells against reactive oxygen species.

It has been proposed that plant growth promoting rhizobacteria (PGPR) stimulate plant growth and development by inducing the biosynthesis of secondary metabolites, like terpenes, which reduce stress incidence. Three bacteria previously isolated from grapevine roots and adjacent soil (Microbacterium imperiale Rz19M10, Kocuria erythromyxa Rt5M10 and Terribacillus saccharophilus Rt17M10) were tested as PGPR. After 30 days since root inoculation of in vitro grown Vitis vinifera cv. Malbec plants, the monoterpenes α-pinene, terpinolene and 4-carene, and the sesquiterpene nerolidol were detected only in bacterized-plant leaves. Also, the concentrations of the diterpenes α and γ-tocopherol, and the sterols sitosterol and lupeol were significantly enhanced compared to controls. The leaf extracts of bacterized plants showed photoprotective properties since they decreased the oxygen consumption (that is photo-oxidation) of the amino acid tryptophan in a sensitized solution, thus indicating an increment of the antioxidant capacity of the tissues. In addition, experiments with α-pinene and nerolidol standards showed the capability to intercept reactive oxygen species in the sensitized solution. Moreover, bacterized plants infected with the pathogen Botrytis cinerea showed a reduction in the lesion diameter compared with non-bacterized plants. The results suggest that M. imperiale, K. erythromyxa and mainly T. saccharophilus are able to induce a systemic response that trigger increases on monoterpenes, sesquiterpenes, tocopherols and membrane sterols. These compounds enhance the antioxidant capacity in leaf tissues that may help grapevine to cope with stresses.

ABA and GA3 increase carbon allocation in different organs of grapevine plants by inducing accumulation of non-structural carbohydrates in leaves, enhancement of phloem area and expression of sugar transporters.

Grape quality for winemaking depends on sugar accumulation and metabolism in berries. Abscisic acid (ABA) and gibberellins (GAs) have been reported to control sugar allocation in economically important crops, although the mechanisms involved are still unknown. The present study tested if ABA and gibberellin A3 (GA3) enhance carbon allocation in fruits of grapevines by modifying phloem loading, phloem area and expression of sugar transporters in leaves and berries. Pot-grown Vitis vinifera cv. Malbec plants were sprayed with ABA and GA3 solutions. The amount of soluble sugars in leaves and berries related to photosynthesis were examined at three points of berry growth: pre-veraison, full veraison and post-veraison. Starch levels and amylase activity in leaves, gene expression of sugar transporters in leaves and berries and phloem anatomy were examined at full veraison. Accumulation of glucose and fructose in berries was hastened in ABA-treated plants at the stage of full veraison, which was correlated with enhancement of Vitis vinifera HEXOSE TRANSPORTER 2 (VvHT2) and Vitis vinifera HEXOSE TRANSPORTER 6 (VvHT6) gene expression, increases of phloem area and sucrose content in leaves. On the other hand, GA3 increased the quantity of photoassimilates delivered to the stem thus increasing xylem growth. In conclusion, stimulation of sugar transport by ABA and GA3 to berries and stems, respectively, was due to build-up of non-structural carbohydrates in leaves, modifications in phloem tissue and modulation in gene expression of sugar transporters.

Acclimation mechanisms elicited by sprayed abscisic acid, solar UV-B and water deficit in leaf tissues of field-grown grapevines.

The independent and interactive effects of solar ultraviolet-B radiation (UV-B), moderate water deficit and sprayed abscisic acid (ABA) on leaves gas exchange and biochemical aspects of field-grown grapevines of the cv. Malbec were investigated in a high altitude vineyard (1450 m a.s.l.). Two UV-B treatments (ambient solar UV-B or reduced UV-B), two watering treatments (well watered or moderate water deficit) and two ABA treatments (no ABA and sprayed ABA) were given alone and combined in a factorial design. Gas exchange and photosynthesis were reduced by water deficit and highly impaired in the UV-B and water deficit combined treatment. UV-absorbing compounds were stimulated independently by UV-B. The monoterpenes α-pinene, 3-carene and terpinolene, and the sesquiterpene nerolidol were augmented by UV-B, water deficit or sprayed ABA. Levels of the triterpene squalene and the diterpene phytol were significantly higher in the treatment that combined UV-B, water deficit and ABA applications. Environment signals (solar UV-B and moderate water deficit) and sprayed ABA elicited mechanisms of acclimation by augmenting the content of terpenes with antioxidant and antifungal properties, thus enhancing the plant defensive mechanisms towards signals both biotic and abiotic.