Tissue-Specific Hormonal Variations in Grapes of Irrigated and Non-irrigated Grapevines (Vitis vinifera cv. “Merlot”) Growing Under Mediterranean Field Conditions

Abstract

Agricultural practices in grapevines management include water restrictions due to its positive effect on wine quality, especially when applied at fruit ripening. Although the effects of water stress in some groups of phytohormones have already been described in leaves and whole grapes, information regarding tissue-specific variations in hormones during ripening in grapes is scarce. Field-grown grapevines from the cv. “Merlot” were subjected to two differential water supplies, including only rainfed, non-irrigated vines (T0) and vines additionally irrigated with 25Lweek−1 vine−1 (T1). Tissue-specific variations in the hormonal profiling of grapes [including changes in the contents of abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), the ethylene precursor 1-amino-cyclopropane-1-carboxylic acid (ACC), the auxin indole-3-acetic acid, gibberellins 1, 3, 4, and 7 (GA1, GA3, GA4, and GA7), the cytokinins trans-zeatin, and 2-isopentenyl adenine, including as well their respective ribosylated forms] were periodically evaluated from veraison to harvest. The hormonal profiling in leaves was also measured at the beginning and end of the season for comparison. Results showed that grape growth dynamics were transiently affected by the differences in water regimes, the increased water supply leading to an accelerated growth, slightly reduced accumulation of sugars, and transiently lowered pH, although grape quality did not differ between treatments at harvest. Hormonal profiling of whole berries did not reveal any difference in the endogenous contents of phytohormones between treatments, except for a transient decrease in GA4 contents in T1 compared to T0 vines, which was not confirmed at the tissular level. Hormonal profiling at the tissue level highlighted a differential accumulation of phytohormones during ripening in berry tissues, with pulps being particularly poor in ABA, JA, and SA contents, seeds particularly accumulating ACC, gibberellins, and zeatin-type cytokinins, and the skin being particularly rich in auxin and active cytokinins. Changes in water supply led to very small and transient changes in the endogenous contents of phytohormones in the seeds, pulp, and skin of berries, the most remarkable variations being observed in cytokinin contents, which increased earlier [between 5 and 12days after veraison (DAV)] but later kept more constant in the skin from T1 compared to T0 vines and were also 3-fold higher at 40 DAV in seeds of T1 compared to T0 vines. It is concluded that small changes in water supply can trigger hormonal-driven physiological adjustments at the tissular level affecting the evolution of fruit growth and quality throughout grape berry ripening.

Drying Grapes after the Application of Different Dipping Solutions: Effects on Hormones, Minerals, Vitamins, and Antioxidant Enzymes in Gök Üzüm (Vitis vinifera L.) Raisins

“…These compounds act on the grape skin by dissolving the waxy components, which causes a high resistance to moisture transfer, and alkaline substances such as potassium carbonate (K 2 CO 3 ) facilitate the moisture transfer by breaking the skin [21]. Ribalta-Pizarro [22] reported that the hormone profile at the tissue level presented a differential accumulation of phytohormones during ripening in berry tissues, with the pulps being particularly poor in ABA, JA, and SA; seeds particularly accumulating ACC, gibberellins, and zeatin-type cytokinins; and the skin being particularly rich in auxin and active cytokinins. In this fashion, we can suggest that potassium carbonate, along with the high temperatures of the pretreatments for drying, led to an important decrease in hormones and the other studied compounds compared to the oak ash dipping solution.…”

Post-Veraison Water Stress and Pruning Level on Merlot Grapevine (Vitis vinifera L.): Effects on Berry Development and Composition

“…e late season dehydration can be attributed to dehydration and loss of berry cell vitality that results in losses of yield, quality, and profitability [11,30]. It has been observed that a severe water stress can originate a sharp decrease in both yield and grape quality, while a mild water stress can help to improve quality but usually decreasing yield [22,39]. e correlation analysis showed a strong negative relationship (r � −0.93) between grape yield and total anthocyanins per berry (Figure 7) as supported by Bindon et al [36], who observed inverse correlation, with total anthocyanins decreasing as yield increased.…”

“…However, if the tissue dehydration exceeds a critical level, a series of irreversible changes in the plant cause death [19]. Grapevines without water deficit has generally been found to cause a delay in ripening, possibly due to the accumulation of juice total soluble solids [20], the dilution effect of organic sugars in an increased berry size which is often associated with an increase in berry weight [21][22][23]. Generally, the effect of water stress on the ripening process may also due to a physiological response to an alteration in plant water status, which in turn impacts the regulation of pathways governing carbon metabolism in the berry [20].…”

Effects on Plant Hormone levels at Different Growth Stages in Diverse Grape Organs with Root Restriction

“…Current studies have proved that the level of endogenous hormones in plants was not only affected by the climate 33 , but also by the cultivation environment and irrigation regime 34,43 . For examples, researchers found the ABA and ethylene signal components were differently accumulated in two distinct climates by analysing the transcriptional expression patterns of carotenoid metabolism in 'Cabernet Sauvignon' (Vitis vinifera L.) grapes 35 , further study also revealed that regulated de cit irrigation (RDI) could signi cantly improve ABA levels in 'Cabernet Sauvignon' (Vitis vinifera L.) wine grapes while reducing IAA levels 36 .…”