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A comprehensive investigation was carried out to determine the effect of exogenous melatonin treatment of pre-veraison grapes on grape berries and its wines. Two melatonin treatments of pre-veraison grape berries increased the weight of the berries by approximately 6.6%. Meanwhile, this melatonin treatment could be beneficial in the reduction of underripe and overripe fruits and in enhancing the synchronicity of the berries. In addition, there were significant differences in the volatile compound composition between the wine produced from the melatonin-treated berries and the wines made from untreated berries. The wine from melatonin-treated pre-veraison grape berries had stronger fruity, spicy, and sweet sensory properties, compared to the wines made from untreated berries. Prolonging the treatment through repeated applications can enhance these effects and under different seasonal conditions, more pronounced effects on the grape quality and wine properties can be observed. [ABSTRACT FROM AUTHOR]

Grapes are an important economic crop and are widely cultivated around the world. Most grapes are grown in arid or semi-arid regions, and droughts take a heavy toll in grape and wine production areas. Developing effective drought-resistant cultivation measures is a priority for viticulture. Melatonin, an indoleamine, mediates many physiological processes in plants. Herein, we examined whether exogenously applied melatonin could improve the resistance of wine grape seedlings grown from cuttings to polyethylene glycol-induced water-deficient stress. The application of 10% polyethylene glycol ( PEG) markedly inhibited the growth of cuttings, caused oxidative stress and damage from H2O2 and [ABSTRACT FROM AUTHOR]

Regulated deficit irrigation (RDI) induces anthocyanins biosynthesis in grape berries; however, the mechanisms involved remain unclear. Here, we compared the change in endogenous hormones in grape berries under RDI treatment and analyzed the effect of nordihydroguaiaretic acid (NDGA), an abscisic acid (ABA) synthesis inhibitor, on anthocyanins biosynthesis in grape berries under RDI treatment. ABA showed the greatest change under RDI treatment; cluster analysis revealed the shortest distance with anthocyanins content. It is noteworthy that NDGA also inhibited the increase in anthocyanins content and the expression of synthesis-related genes in grape berries. ABA promoted anthocyanins accumulation by enhancing the expression of VvMYBPA1 and VvOMT in RDI-treated grape berries. In addition, RDI mainly promoted the synthesis and accumulation of monoglycosides anthocyanins, as well as the accumulation of malvidin-3- O -glucoside and its derivatives. These results indicated that ABA signaling plays key roles in RDI-induced anthocyanins accumulation in grape berries. [ABSTRACT FROM AUTHOR]