The biosynthesis of S-(3-hexan-1-ol)-glutathione (3MH-S-glut) and S-(3-hexan-l-ol)-L-cysteine (3MH-S-cys), which act as flavour precursors in wines, in Vitis vinifera grapes exposed to various environmental stress conditions is reported here. Ultraviolet (UV-C) irradiation, water deficit, and biological stimulation up-regulated 3MH-S-glut and 3MH-S-cys biosynthesis in grape leaves. 3MH-S-glut and 3MH-S-cys contents in grape berries were increased by cold shock, heat shock, UV-C irradiation, and biological stimulation. The results suggest that environmental stress enhances the biosynthesis of both flavour precursors in grapevine. The transcription of VvGST1, VvGST3, VvGST4, and GGT in grapevine exposed to the stress conditions was increased markedly compared with that in control grapevine. Also, UV irradiation increased GST (glutathione S-transferase) and GGT (γ-glutamyl transferase) enzyme activities in grape berries. Recombinant VvGST3 and VvGST4, but not VvGST1, mediated the synthesis of 3MH-S-glut from reduced glutathione and trans-2-hexenal in vitro. The enzymatic mediation of flavour precursor production is a novel function of plant GSTs and may result in the detoxification of damaged grape cells under stress conditions.

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Spontaneously hypertensive rats receiving CD diet showed severe hepatic steatosis associated with reduction of hepatic anti-oxidant capacity, leading to increased hepatic oxidative stress and tissue damage. Accordingly, hypertension might have a potential effect on the progression of NASH.

We report here that pink grape berries were obtained by a short insertion in the intron of the MybA1 gene, a gene that regulates grape berry color. Genetic variation was detected among the MybA1 genes from grapes cultivated worldwide. PCR analysis of the MybA1 gene demonstrated that the size of the MybA1 gene in the red allele differs among grapes. Oriental V. vinifera bearing pink berries has the longest MybA1 gene among grapes, whereas the shortest MybA1 gene was detected in occidental V. vinifera grapes. The nucleotide sequences of the MybA1 genes demonstrated that oriental V. vinifera has two additional gene fragments (44 bp and 111 bp) in the promoter region of the MybA1 gene in the red allele and another 33 bp fragment in the second intron of the MybA1 gene in the red allele. The short insertion in the intron decreased the transcription activity in the model system and retained MybA1 transcripts with unspliced intron in the total RNA. From the experiments using deletion mutants of the 33 bp short insertion, 16 bp of the 3′ end in the insertion is a key structure for a defect in splicing of MybA1 transcripts. Thus, a weakly colored grape berry might be a result of the short insertion in the intron of a color regulatory gene. This is new evidence concerning the molecular mechanism of the fate of grape berry color. These findings are expected to contribute to the further understanding of the color variation in grape berries, which is correlated with the evolutional events occurring in the MybA1 gene of grapes.

We report the characterization of VvIAA19, an auxin/indole-3-acetic acid (Aux/IAA) protein, in grapevine (Vitis vinifera L.). VvIAA19 was expressed abundantly in berries. VvIAA19 transcription was rapidly increased at pre-anthesis and then decreased during fruit set. Before véraison, however, VvIAA19 gene expression was upregulated again and maximum expression was maintained until the end of ripening. Exogenous IAA did not induce VvIAA19 expression in grape leaves, suggesting that VvIAA19 might be auxin-nonresponsive. The overexpression of VvIAA19 in Arabidopsis thaliana had a notable effect on plant growth. Although no morphological changes were observed, transgenic Arabidopsis plants overexpressing VvIAA19 exhibited faster growth, including root elongation and floral transition, than the control plant, suggesting that the constitutive expression of VvIAA19 protein resulted in increased growth rates without any detectable harm. Taken together, we conclude that grape Aux/IAA19 protein is likely to play a crucial role as a plant growth regulator.