Du Chen-Lu, Cai Chun-Liu, Lu Yi, Li You-Mei, Xie Zhao-Sen
College of Horticulture and Landscape, Yangzhou University, Yangzhou, China.
Mol Genet Genomics. 2023 May;298(3):777-789. doi: 10.1007/s00438-023-02015-3. Epub 2023 Apr 11.
Sugar is crucial for grape berry, whether used for fresh food or wine. However, berry enlargement treatment with forchlorfenuron (N-(2-chloro4-pyridyl)-N'-phenylurea) (CPPU, a synthetic cytokinin) and gibberellin (GA) always had adverse effects on sugar accumulation in some grape varieties, especially CPPU. Therefore exploring the molecular mechanisms behind these adverse effects could provide a foundation for improving or developing technology to mitigate the effects of CPPU/GA treatments for grape growers. In the present study, invertase (INV) family, the key gene controlling sugar accumulation, was identified and characterized on the latest annotated grape genome. Their express pattern, as well as invertase activity and sugar content, were analyzed during grape berry development under CPPU and GA treatment to explore the potential role of INV members under berry enlargement treatment in grapes. Eighteen INV genes were identified and divided into two sub-families: 10 neutral INV genes (Vv-A/N-INV1-10) and 8 acid INV genes containing 5 CWINV (VvCWINV1-5) and 3 VIN (VvVIN1-3). At the early development stage, both CPPU and GA treatment decreased the hexose level in berries of 'Pinot Noir' grape, whereas the activity of three types inverstase (soluble acid INV, insoluble acid INV, and neutral INV) increased. Correspondingly, most of INV members were up-regulated by GA /CPPU application at least one sampling time point during early berry development, including VvCWINV1, 2, 3, 4, 5, VvVIN1, 2, 3 and Vv-A/N-INV1, 2, 5, 6, 7, 8, 10. At maturity, the sugar content in CPPU-treated berries is still lower than that in the control. Soluble acid INV and neutral INV, rather than insoluble acid INV, presented lower activity in CPPU-treated berries. Meanwhile, several corresponding genes, such as VvVIN2 and Vv-A/N-INV2, 8, 10 in ripening berries were obviously down-regulated by CPPU treatment. These results suggested that most of INV members could be triggered by berry enlargement treatment during early berry development, whereas VvVINs and Vv-A/N-INVs, but not VvCWINVs, could be the limiting factor resulting in decreased sugar accumulation in CPPU-treated berries at maturity. In conclusion, this study identified the INV family on the latest annotated grape genome and selected several potential members involving in the limit of CPPU on final sugar accumulation in grape berry. These results provide candidate genes for further study of the molecular regulation of CPPU and GA on sugar accumulation in grape.
糖分对于葡萄果实至关重要，无论是用于鲜食还是酿酒。然而，用氯吡脲（N-(2-氯-4-吡啶基)-N'-苯基脲）（CPPU，一种合成细胞分裂素）和赤霉素（GA）进行的果实膨大处理，在一些葡萄品种中总是对糖分积累产生不利影响，尤其是CPPU。因此，探究这些不利影响背后的分子机制可为葡萄种植者改进或开发减轻CPPU/GA处理影响的技术提供基础。在本研究中，在最新注释的葡萄基因组上鉴定并表征了控制糖分积累的关键基因——转化酶（INV）家族。分析了它们在CPPU和GA处理下葡萄果实发育过程中的表达模式，以及转化酶活性和糖分含量，以探究INV成员在葡萄果实膨大处理中的潜在作用。鉴定出18个INV基因，并分为两个亚家族：10个中性INV基因（Vv-A/N-INV1-10）和8个酸性INV基因，其中包括5个细胞壁转化酶（VvCWINV1-5）和3个液泡转化酶（VvVIN1-3）。在发育早期，CPPU和GA处理均降低了‘黑皮诺’葡萄果实中的己糖水平，而三种类型的转化酶（可溶性酸性INV、不溶性酸性INV和中性INV）的活性增加。相应地，在果实发育早期的至少一个采样时间点，大多数INV成员被GA/CPPU处理上调，包括VvCWINV1、2、3、4、5、VvVIN1、2、3和Vv-A/N-INV1、2、5、6、7、8、10。在成熟时，CPPU处理的果实中的糖分含量仍低于对照。在CPPU处理的果实中，可溶性酸性INV和中性INV而非不溶性酸性INV的活性较低。同时，在成熟果实中，一些相应的基因，如VvVIN2和Vv-A/N-INV2、8、10，被CPPU处理显著下调。这些结果表明，在果实发育早期，大多数INV成员可被果实膨大处理触发，而VvVINs和Vv-A/N-INVs而非VvCWINVs可能是导致CPPU处理的果实成熟时糖分积累减少的限制因素。总之，本研究在最新注释的葡萄基因组上鉴定了INV家族，并筛选出了几个参与CPPU对葡萄果实最终糖分积累限制的潜在成员。这些结果为进一步研究CPPU和GA对葡萄糖分积累的分子调控提供了候选基因。
