Drought events are a major challenge for many horticultural crops, including grapes, which are often cultivated in dry and warm climates. It is not understood how the cuticle contributes to the grape berry response to water deficit (WD), furthermore the cuticular waxes and the related biosynthetic pathways are poorly characterized in this fruit. In this study, we identified candidate wax-related genes from the grapevine genome by phylogenetic and transcriptomic analyses. Developmental and stress-response expression patterns of these candidates were characterized across pre-existing RNA-seq datasets and confirmed a high responsiveness of the pathway to environmental stresses. We then characterized the developmental and WD induced changes in berry cuticular wax composition, and quantified differences in berry transpiration. Cuticular aliphatic wax content was modulated across development and an increase was observed under WD, with wax esters being strongly upregulated. These compositional changes were related to upregulated candidate genes of the aliphatic wax biosynthetic pathway, including CER10, CER2, CER3, CER1, CER4, and WSD1. The effect of WD on berry transpiration was not significant. This study indicates that changes in cuticular wax amount and composition are part of the metabolic response of the grape berry to WD, but these changes do not reduce berry transpiration.

中文翻译：

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干旱胁迫调节葡萄浆果的角质层蜡成分。


干旱事件对许多园艺作物来说是一个重大挑战，其中包括通常在干燥和温暖气候下种植的葡萄。目前尚不清楚角质层如何影响葡萄浆果对缺水（WD）的反应，此外，这种水果中的角质层蜡和相关的生物合成途径的特征也很少。在这项研究中，我们通过系统发育和转录组分析从葡萄基因组中鉴定出与蜡相关的候选基因。这些候选者的发育和应激反应表达模式在现有的 RNA-seq 数据集中进行了表征，并证实了该途径对环境应激的高响应性。然后，我们描述了发育和 WD 引起的浆果角质层蜡成分的变化，并量化了浆果蒸腾作用的差异。角质层脂肪蜡含量在发育过程中受到调节，并且在 WD 下观察到增加，其中蜡酯被强烈上调。这些成分变化与脂肪蜡生物合成途径的候选基因上调有关，包括 CER10、CER2、CER3、CER1、CER4 和 WSD1。 WD对浆果蒸腾作用的影响不显着。这项研究表明，表皮蜡量和成分的变化是葡萄浆果对 WD 代谢反应的一部分，但这些变化不会减少浆果蒸腾作用。