BACKGROUND Light conditions significantly influence grape berry ripening and the accumulation of phenolic compounds, but the underlying molecular basis remains partially understood. Here, we applied integrated transcriptomics and pathway-level metabolomics analyses to investigate the effect of cluster bagging during various developmental stages on phenolic metabolism in Cabernet Sauvignon grapes. RESULTS Bagging treatments had limited effects on berry quality attributes at harvest and did not consistently affect phenolic acid biosynthesis between seasons. Significantly elevated flavan-3-ol and flavonol contents were detected in re-exposed berries after bagging during early-developmental stages, while bagging after véraison markedly inhibited skin anthocyanin accumulation. Several anthocyanin derivatives and flavonol glycosides were identified as marker phenolic metabolites for distinguishing bagged and non-bagged grapes. Coordinated transcriptional changes in the light signaling components CRY2 and HY5/HYHs, transcription regulator MYBA1, and enzymes LAR, ANR, UFGT and FLS4, coincided well with light-responsive biosynthesis of the corresponding flavonoids. The activation of multiple hormone signaling pathways after both light exclusion and re-exposure treatments was inconsistent with the changes in phenolic accumulation, indicating a limited role of plant hormones in mediating light/darkness-regulated phenolic biosynthesis processes. Furthermore, gene-gene and gene-metabolite network analyses discovered that the light-responsive expression of genes encoding bHLH, MYB, WRKY, NAC, and MADS-box transcription factors, and proteins involved in genetic information processing and epigenetic regulation such as nucleosome assembly and histone acetylation, showed a high positive correlation with grape berry phenolic accumulation in response to different light regimes. CONCLUSIONS Altogether, our findings provide novel insights into the understanding of berry phenolic biosynthesis under light/darkness and practical guidance for improving grape features.

中文翻译：

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比较的生理，代谢组学和转录组学分析揭示了套袋对赤霞珠葡萄浆果中酚类代谢的发育阶段依赖性。

背景技术光照条件显着影响葡萄浆果的成熟和酚类化合物的积累，但是其潜在的分子基础仍被部分理解。在这里，我们应用综合的转录组学和途径水平的代谢组学分析来研究在不同发育阶段的套袋对赤霞珠葡萄中酚类代谢的影响。结果套袋处理对收获时浆果品质属性的影响有限，并且在不同季节之间并不能始终如一地影响酚酸的生物合成。套袋后在早期发育阶段，重新暴露的浆果中检测到的黄烷-3-醇和黄酮醇含量显着升高，而变味后的套袋则明显抑制了皮肤花色苷的积累。几种花色苷衍生物和黄酮醇苷被鉴定为标志性酚类代谢产物，用于区分袋装和非袋装葡萄。光信号成分CRY2和HY5 / HYHs，转录调节因子MYBA1以及酶LAR，ANR，UFGT和FLS4的协调转录变化与相应类黄酮的光响应生物合成相吻合。光排除和再暴露处理后多种激素信号通路的激活与酚类积累的变化不一致，表明植物激素在介导光/暗调节酚类生物合成过程中的作用有限。此外，通过基因-基因和基因-代谢网络分析发现，编码bHLH，MYB，WRKY，NAC和MADS-box转录因子的基因具有光响应性表达，以及涉及遗传信息处理和表观遗传调控的蛋白质（例如核小体装配和组蛋白乙酰化）与葡萄浆果酚类物质的积累在不同的光照条件下呈高度正相关。结论总的来说，我们的发现为在明暗之间了解浆果酚类生物合成提供了新颖的见解，并为改善葡萄特性提供了实用指导。