Modification of skin anatomy and phenolic compounds of Tannat grapes along ripening by abscisic acid foliar applications

The ‘Tannat’ grapevine variety is known for its high polyphenolic content in grapes but low anthocyanin extractability. Secondary metabolite accumulation during ripening is influenced by a complex interplay of environmental factors and plant responses. While scientific literature indicates that abscisic acid (ABA) applications at veraison can modify the polyphenolic content of grapes, the effects can vary based on the dosage and climatic conditions. However, limited literature exists on the changes of grape skin anatomy in response to exogenous ABA applications during ripening. This study aimed to investigate the effects of ABA applications on ‘Tannat’ grapevines on the grape skin anatomy and polyphenolic compounds during ripening at two different locations. The results demonstrate that location was a key factor that significantly affected grape polyphenol content, under temperate-warm climate conditions and temperate, sub-humid nights (TSH) resulting in higher phenolic compound levels. Additionally, warm climates favored anthocyanin extractability. Grape skin cell typologies evolve differentially; while empty cells (type I) were independent of the climatic conditions, cells with anthocyanin accumulations (type II, III, IV and V) vary based on their polymerization degree in response to the climate conditions. ABA applications increased the total anthocyanin contents in the grapes harvested in the TSH location but did not affect their content in the WH site. The evolution of the anatomy of skin cells of ‘Tannat’ can help to better adjust ‘Tannat’ vineyard management in different viticulture regions (canopy management, exogenous ABA treatments, irrigation) and to improve wine production techniques (maceration days for anthocyanins extractability, aging of wines, etc.)

Sustainable Strategies to Prevent Iron Deficiency, Improve Yield and Berry Composition in Blueberry (Vaccinium spp.)

The aim of this investigation was to study the effect of sustainable strategies to correct iron deficiency in blueberries, based on Fe-heme applications or intercropping with graminaceous species, on yield, and berry quality variables. The experiment was conducted in a blueberry orchard established in a sub-alkaline soil. The association with grasses increased the crop load and yield (only Festuca rubra), and decreased the skin/flesh ratio. In addition, these treatments increased anthocyanins as well as some hydroxybenzoic acids, hydroxycinnamic acids, flavanols, and flavonol concentrations in skins with a similar effectiveness as Fe-EDDHA, whereas the Fe-heme applications did not influence such parameters. Moreover, data revealed that the association with both grasses decreased the firmness of the berries, whereas none of the treatments assessed changed the soluble solids, pH, acidity, and the soluble solids/acidity rate compared to the control. These results suggest that Fe nutrition is crucial for yield and berry quality in blueberry, and that intercropping with grasses may be an effective and sustainable alternative to counteract Fe deficiency in blueberry, with a similar effect on berries to that achieved with Fe-EDDHA

Water deficit differentially modulates leaf photosynthesis and transpiration of fungus-tolerant Muscadinia x Vitis hybrids

Screening for drought performance among novel fungi-tolerant grapevine genotypes is a key point to consider in semiarid regions where water scarcity is a common problem during fruit ripening period. It is therefore important to evaluate the genotypes’ responses at the level of carbon metabolism and water demand, under water deficit conditions. This study aimed to characterize leaf and plant water use efficiency (respectively named WUEi and WUEpl) of novel INRAE fungi-tolerant genotypes (including LowSugarBerry (LSB) genotypes), under mild and high-water deficit (WD) and to decipher the photosynthetic parameters leading to higher WUEi. For this purpose, experiments were conducted on potted plants during one season using a phenotyping platform. Two stabilized soil moisture capacity (SMC) conditions, corresponding to mild (SMC 0.6) and high (SMC 0.3) WD, were imposed from the onset of berry ripening until the physiological ripeness stage, which was defined as the point at which fruits reach their maximum solutes and water content. At the whole plant level, all genotypes increased WUEpl under high WD. The highest WUEpl was reached for 3176N, which displayed both a high rate of non-structural carbon accumulation in fruits due to high fruit-to-leaf ratio and low plant transpiration because of low total leaf area. However, when normalizing the fruit-to-leaf ratio among the genotypes, G14 reached the highest normalized WUEpl_n under high WD. At the leaf level, WUEi also increased under high WD, with the highest value attained for G14 and 3176N and the lowest value for Syrah. The higher WUEi values for all genotypes compared to Syrah were associated to higher levels of photosynthesis and changes in light-harvesting efficiency parameters (ΦCO2, qP and qN), while no clear trend was apparent when considering the photosynthetic biochemical parameters (Vcmax, Jmax). Finally, a positive correlation between leaf and plant WUE was observed regardless of genotypes. This study allowed us to classify grapevine genotypes based on their grapes primary metabolite accumulation and water consumption during the critical sugar-loading period. Additionally, the study highlighted the potential drought adaptation mechanism of the LSB genotypes

Efecto de la temperatura, el estrés hídrico y luminoso sobre la heterogeneidad del fotosistema II en cuatro variedades de poroto (Phaseolus vulgaris L.) Effect of temperature, water and light stress on PSII heterogeneity in four bean varieties (Phaseolus vulgaris L.)

Las plantas superiores, requieren de mecanismos que permitan proteger a los centros fotosintéticos de daño oxidativo, particularmente en condiciones ambientales que determinen una absorción luminosa en exceso de su capacidad de utilización fotoquímica, como son las altas intensidades de luz, propiamente tal, restricción de agua y aumentos de temperatura. En el mediano y largo plazo los centros PSII tendrían la capacidad de modificar su localización y estructura, formando los centros PSII del tipo ß y los estados de transición, cuya variación no depende, exclusivamente, de la intensidad luminosa. En el presente estudio se determinó el efecto de distintos estreses ambientales sobre la heterogeneidad del PSII, en cuatro cultivares de poroto: Arroz Tuscola (AT), Orfeo INIA (OI), Bayos Titán (BT) y Hallado Dorado (HD). En plantas desarrolladas en cámaras de crecimiento, la proporción de centros PSIIß aumentó hasta en un 100 % en la medida que se incrementó la temperatura. Dicho efecto fue magnificado por el estrés hídrico, en estas plantas. En condiciones de campo, el estrés lumínico impuesto por la fijación de folíolos a la posición horizontal, aumentó aun más el efecto del estrés hídrico sobre la proporción de tales centros, desde un 27 %, en plantas regadas y hoja en posición normal, hasta un 63 % en plantas estresadas y hojas forzadas a la horizontalidad. En cuanto a los estados de transición, se observó, en plantas desarrolladas a 20 ºC en cámaras de crecimiento, un aumento de estos al someter sus hojas a 15 ºC. Así mismo, temperaturas de 25 a 35 ºC indujeron aumentos en los estados de transición. El estrés hídrico, en los cultivares AT y OI, aminoró la magnitud del efecto de la temperatura, al contrario de lo observado en BT. En el cultivar HD, no se distingue un efecto claro del estrés hídrico, sobre la formación de los estados de transición inducidos por cambios en la temperatura. Aún cuando existen diferencias en la magnitud de los cambios observados en las diferentes variedades de poroto, en todos ellos se aprecia la tendencia a modificar la estructura de los centros PSII, de manera de favorecer una menor sobreexcitación de los centros de reacción de dichos complejos, en las situaciones de estrés estudiadasHigher plants have developed multiple mechanisms of photoprotection in order to efficiently use the absorbed energy, as well as protecting the photosynthetic apparatus against oxidative damage. Particularly, under environmental conditions, restrictive for the photochemical use of the absorbed energy, such as high light, water stress and high temperatures. PSII complexes are able to change their location and structure as in PSIIß and state transitions, but not exclusively upon light intensity. In the present study, the effect of different environmental stresses on PSII heterogeneity in four bean cultivar (Phaseolus vulgaris L.): Arroz Tuscola (AT), Orfeo INIA (OI), Bayos Titán (BT) and Hallado Dorado (HD), has been assessed. In chamber grown plants, the proportion of the PSIIb centers increases up to a 100 % as the temperature rises. A stronger response was observed, upon water stress. Under field conditions, light stress induced by fixing leaves to horizontal position, further increased the water stress dependent effect on PSIIb centers, from 27 % in free leaves from watered plants up to a 63 % in horizontal leaves from water stressed plants. As for state transitions, an increase was observed in 20 ºC grown plants when exposed to 15 ºC. Also, temperatures from 25 to 35 ºC induced increases in state transitions. Such increases were lowered by water stress, in cultivars AT and OI, maintained in HD and further increased in BT. Even though differences were observed in the extent of the changes on PSIIß and state transitions among varieties, a clear trend to modify the PSII structure in order to decrease its excitation pressure under the stress conditions studied were observe

Water-stress-induced thermotolerance of photosynthesis in bean (Phaseolus vulgaris L.) plants: The possible involvement of lipid composition and xanthophyll cycle pigments

A common feature in plants that are exposed to gradual stressful environmental factors is the development of a level of resistance to such constraints, which sometimes protects against different stressful environmental conditions. The aim of this study was to assess a possible cross-resistance between water stress and high-temperature stress and to gain a better knowledge regarding the physiological basis for heat resistance. The study was performed in two bean varieties; Orfeo INIA (OI) and Arroz Tuscola (AT) are a stress-resistant and stress-sensitive variety, respectively. An increased heat resistance in OI but not in AT results from water stress as revealed by the oxygen-evolution rate at 38 ◦C and the thermal threshold for non-reversible damage that was assessed by the temperature-dependent increases in basal fluorescence (F0); higher values of both parameters were observed in the leaves of waterstressed plants when compared to the control OI plants. The heat-shock proteins HSP70, HSP60 and HSP24 do not seem to be involved in the water-stress-induced resistance to high temperature because no difference in their contents was found between the water-stressed and control plants. The important features in the water-stressed OI plants, which can resist higher temperatures, are the maintenance of the xanthophyll pigment contents compared to the control plants and in contrast to the sensitive AT plants, an increase in phosphatidylglycerol and a reduction in the unsaturation level of the thylakoid fatty acids. The results from the comparative analyses of the xanthophyll, lipid and fatty acid compositions in the chloroplasts of well-watered and water-stressed AT and OI plants are discussed in terms of their possible involvement in conferring resistance to high temperature in water-stressed bean leaves

Anthocyanin Composition in Cabernet Sauvignon Grape Skins: Effect of Regulated Deficit Irrigation in a Warm Climate

The influence of regulated deficit irrigation on the anthocyanin composition in Cabernet Sauvignon grape skins throughout ripening and when grown in a warm geographic area for two consecutive seasons was investigated. The assay was carried out on own-rooted Cabernet Sauvignon plants maintained under three irrigation regimes (i.e., T1 = 12 L h−1 (90% of ETp), T2 = 6 L h−1 (60% of ETp) and T3 = 2 L h−1 (30% of ETp)) from veraison until harvest. The results showed that the concentration of total anthocyanins varied among the three groups. In terms of the different fractions of anthocyanins, mild water stress generated slight changes with a different behavior between the 2014 and 2015 seasons, although the pattern of accumulation was similar. The trihydroxylated anthocyanins were much higher in concentration than the dihydroxylated counterparts in both seasons, with no significant differences among irrigation treatments. The water status did not produce differences in terms of the different anthocyanin proportions at harvest, which could indicate that the different irrigation treatments did not induce a greater accumulation of one or another type of anthocyanin

Response of sink manipulation in ?Lapins? sweet cherry (Prunus avium L.) branches to late-deficit irrigation

Photosynthetic traits, leaf soluble sugars and fruit yield and size were evaluated in order to identify the role of early sink manipulation (girdling and fruiting spur thinning applied in winter) in modulating the effect of latedeficit irrigation (recovering 60% of crop evapotranspiration during 36 days pre harvest) in 'Lapins' sweet cherry branches. Photosynthesis (PN), stomatal conductance (gs), and fruit weight were affected by both treatments, whereas intercellular CO2 concentration of leaves (Ci), mesophyll conductance (gm), Rubisco carboxylase activity (Vcmax), electron transport rate (Jmax), leaf soluble sugars and branch yield were exclusively affected by sink manipulation. The effect of sink manipulation on PN was mainly observed in the girdling treatment as it was not altered by thinning. In girdled branches, PN dropped by 34%, accompanied by a two fold increase in leaf soluble sugars, indicating that sink feedback regulation of carbon assimilation occurred. Irrespective of the irrigation, the higher PN observed in the controls were not sufficient to achieve the fruit weight and yield of the girdled branches, indicating that fruit carbon demand in control branches was source limited. The depressed PN by girdling was associated with significant reductions in gs, gm, Vcmax and Jmax. Since lowered PN by deficit irrigation was neither attributable to a gs associated decrease in Ci nor to changes in any other photosynthetic variable, further research is needed to clarify this point. Results showed that irrigation deficit was sufficient to reduce PN in girdled branches, whereas it had no effect in control and thinned branches. Thus, the depressive effect of deficit irrigation on PN appeared to be exacerbated by the sink effect