Sugar and its metabolism play a critical role in fruit quality and determine the accumulation characteristics of secondary metabolites. In this study, the dynamic changes in anthocyanin and proanthocyanidin (PA) accumulation during exogenous sugar application were investigated throughout the grape ripening stage, and the underlying biosynthesis mechanism was monitored. Results showed that exogenous sucrose and -acetyl--glucosamine (hexokinase inhibitor, HI) promoted grape berry ripening. Exogenous application of sucrose and HI significantly increased the levels of soluble sugars and anthocyanins, while significantly decreased the levels of acids and PAs in grape berries. Exogenous sucrose and HI activated the transcription of the and genes but inhibited the transcription of gene to alter sugar metabolism. Notably, the accumulation of anthocyanin compounds, particularly peonidin derivatives, significantly increased in the sucrose- and HI-treated berries by upregulating the transcription of anthocyanin biosynthesis genes, including , and , whereas the accumulation of PA units, such as (‒)-epicatechin, (+)-gallocatechin, and (‒)-epigallocatechin, was repressed by downregulating the transcription of the and genes, which boosted anthocyanin and PA reprogramming. These results provide preliminary information on how to modulate the biosynthesis and accumulation of anthocyanins and PAs in grape berries by the exogenous application of sucrose and thus, to modify berry composition.

中文翻译：

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外源施用蔗糖促进‘赤霞珠’葡萄浆果中花青素和原花青素的重新分配


糖及其代谢对果实品质起着至关重要的作用，决定着次生代谢物的积累特征。在本研究中，研究了在整个葡萄成熟阶段施用外源糖期间花青素和原花青素（PA）积累的动态变化，并监测了潜在的生物合成机制。结果表明，外源蔗糖和-乙酰-氨基葡萄糖（己糖激酶抑制剂，HI）促进葡萄浆果成熟。外源施用蔗糖和HI显着提高了葡萄浆果中可溶性糖和花青素的含量，同时显着降低了葡萄浆果中酸和PA的含量。外源蔗糖和HI激活和基因的转录，但抑制基因的转录，从而改变糖代谢。值得注意的是，通过上调花青素生物合成基因（包括 、 和 ）的转录，蔗糖和 HI 处理的浆果中花青素化合物（特别是芍药苷衍生物）的积累显着增加，而 PA 单位（如 (-)-表儿茶素）的积累显着增加。 、(+)-没食子儿茶素和(-)-表没食子儿茶素通过下调 和 基因的转录而受到抑制，从而促进花青素和 PA 重编程。这些结果为如何通过外源施用蔗糖来调节葡萄浆果中花青素和 PA 的生物合成和积累从而改变浆果成分提供了初步信息。