Cytokinin and gibberellic acid (GA) are growth regulators used to increase berry size in seedless grapes and it is of interest to understand their effects on the phenylpropanoid pathway and on ripening processes. GA3 and synthetic cytokinin forchlorfenuron (N-(2-chloro-4-pyridyl)-N′-phenylurea, CPPU) and their combination were applied to 6 mm diameter fruitlets of ‘Sable Seedless’, and berries were sampled 51 and 70 days (d) following application. All treatments increased berry size and delayed sugar accumulation and acid degradation with a stronger effect of CPPU. CPPU, but not GA, reduced berry color and the levels of anthocyanins. While CPPU reduced the levels of anthocyanins by more than 50%, the combined treatment of GA+CPPU reduced the levels by about 25% at 51 d. CPPU treatment had minor effects on flavonols content but increased the levels of monomeric flavan-3-ols by more than two-fold. Phloroglucinol analysis using HPLC showed that proanthocyanidin content was significantly increased by CPPU, whereas mean degree of polymerization was reduced from 26 to 19. Volatile analysis by GC-MS showed changes in composition with CPPU or GA treatment with potential impact on flavor. RNA-seq analysis showed that GA had a minor overall effect on the transcriptome whereas CPPU had pronounced effects on gene expression at both 51 and 70 d. Comparing the control and CPPU at similar Brix of ca. 19.7°, a reduced expression of stilbene synthases (STSs) including their regulators MYB14 and MYB15, and other phenylpropanoid-related genes was observed in CPPU-treated grapes. Overall, our study shows that CPPU had a major influence on the phenylpropanoid pathway and affected multiple ripening-related processes.

中文翻译：

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细胞分裂素而不是赤霉素的应用对葡萄中的苯丙素途径有重大影响

细胞分裂素和赤霉酸 (GA) 是用于增加无核葡萄浆果大小的生长调节剂，了解它们对苯丙素途径和成熟过程的影响很有意义。遗传算法3和合成的细胞分裂素氯苯脲 (N-(2-chloro-4-pyridyl)-N'-phenylurea, CPPU) 及其组合应用于 6 mm 直径的“Sable Seedless”小果，并在 51 天和 70 天（d ) 以下应用程序。所有处理都增加了浆果的大小并延迟了糖的积累和酸降解，而 CPPU 的作用更强。CPPU，但不是 GA，降低了浆果的颜色和花青素的水平。虽然 CPPU 降低了 50% 以上的花青素水平，但 GA+CPPU 的联合处理在第 51 天降低了约 25% 的水平。CPPU 处理对黄酮醇含量的影响较小，但单体黄烷-3-醇的含量增加了两倍以上。使用 HPLC 分析间苯三酚表明，CPPU 显着增加了原花青素含量，而平均聚合度从 26 降低到 19。通过 GC-MS 进行的挥发性分析显示，CPPU 或 GA 处理后的成分发生变化，可能对风味产生影响。RNA-seq 分析显示 GA 对转录组的整体影响较小，而 CPPU 在 51 天和 70 天对基因表达有显着影响。比较控制和 CPPU 在类似白利糖度的 ca。19.7°，简化表达二苯乙烯合酶（STS），包括其监管机构MYB14和MYB15, 和其他苯丙烷相关基因在 CPPU 处理的葡萄中观察到。总体而言，我们的研究表明，CPPU 对苯丙烷途径产生了重大影响，并影响了多个与成熟相关的过程。