UV-C诱导葡萄果实黄烷醇类多酚和花色苷积累机制的研究

Flavanols and anthocyanins are the main polyphenolic compounds in the grape berry. Numerous researches had idicated that the ultraviolet-C (UV-C) could induce the accumulation of flavanols and/or anthocyanins in the grape berry. However, the accumulation mechanisms of flavanols and anthocyanins induced by UV-C in grape berry were still obscure. Based on our previous researches, the grapevine (Vitis vinifera L. Cabernet Sauvignon and Chardonnay) were subjected to the regular UV-C irradiation during the berry development, and the temporal and spatial auucumlations of flavanols and anthoycanins in berries were studied fristly. Secondly, the expression of DFR, LAR, ANS, ANR, and UFGT, the key enzyme involved the biosynthesis of flavanols and anthoycanins in grape berry were analysed in terms of enzyme activity, protein amount, and mRNA transcriptional level, which should improve our understanding in the accumulation mechanism of flavanols and anthocyanins induced by UV-C in grape berry. Thirdly, the expression characteristics of MybA1, and MybA2, as well as MybPA1,and MybPA2, which regulated the biosynthesis anthocyanins and flavanols respectively in grape berry were also studied. This project was aimed to further illustrate the accumulation mechanism of flavanols and anthocyanins and flavanols in grape berry induced by UV-C, especially the differences in the accumulation mechanism of flavanols and anthocyanins, and provided a theoretical basis for the artificial regualtion of quality of grape berry and wine.

黄烷醇类多酚和花色苷是葡萄果实中主要的多酚类物质。前期研究表明，UV-C照射诱导葡萄果实黄烷醇类多酚和/或花色苷积累。但迄今为止，其诱导机理尚不明确。在前期研究基础上，本项目以红色品种赤霞珠（Cabernet Sauvignon）和白色品种霞多丽（Chardonnay）为试材，在果实发育过程中定期进行UV-C活体照射，以黄烷醇类多酚和花色苷生物合成关键酶DFR、LAR、ANS、ANR、UFGT为切入点，从底物、酶活性、酶蛋白含量及结构基因转录水平四个层次揭示UV-C诱导积累的机理；并就特异性调控花色苷合成的MybA1、MybA2和黄烷醇类多酚合成的MybPA1、MybPA2转录因子的表达特性进行研究，以期阐明UV-C诱导黄烷醇类多酚和花色苷积累的机制，特别是UV-C诱导黄烷醇类多酚和花色苷积累机制的差异，进一步完善紫外线诱导的多酚积累机理研究，为人为调控葡萄果实乃至葡萄酒品质提供理论依据。

黄烷醇类多酚和花色苷是葡萄果实中重要的多酚类物质，对葡萄及其加工品葡萄酒品质和保健功能具有决定性作用。本项目以赤霞珠（Vitis vinifera L. Cabernet Sauvignon）和霞多丽（Vitis vinifera L. Chardonnay）为试材，进行定期活体UV-C照射，阐明果实发育进程中UV-C诱导黄烷醇类多酚和花色苷时空积累机制；以黄烷醇类多酚和花色苷生物合成关键酶DFR、LAR、ANS、ANR、UFGT为切入点，从底物、酶活性、翻译和转录水平揭示UV-C诱导积累的生理生化机制；以转录因子MybA1、MybA2、MybPA1、MybPA2为对象，揭示UV-C诱导积累的调控机制。.研究结果表明，葡萄果实发育过程中，UV-C照射并不能改变果实中黄烷醇类多酚和花色苷积累规律，但能够促进黄烷醇类多酚和/或花色苷积累，且这一诱导作用具有剂量、发育阶段和器官依赖性。UV-C照射对DFR、LAR、ANS、ANR、UFGT等黄烷醇类多酚和花色苷生物合成关键酶活性具有明显的调控作用，特别是对幼果期的LAR、转色期的ANS和UFGT、成熟期的ANR酶活性具有明显的激活作用；但对酶活性的调控作用因品种、果实发育阶段不同而不同。UV-C照射对黄烷醇类多酚和花色苷生物合成关键酶蛋白表达规律无明显作用，但具有明显的诱导作用，特别是对幼果期LAR1、LAR2、ANR，转色期ANS，转色期和成熟期的UFGT，且这一诱导作用具有发育阶段和品种依赖性。UV-C照射诱导葡萄果实Vv DFR、Vv LAR1、Vv LAR2、Vv ANS、Vv ANR、Vv UFGT等结构基因表达，特别是幼果期时Vv LAR1、Vv LAR2、Vv ANR，转色期Vv ANS、Vv UFGT转录。在获得葡萄果实Myb A1、A2、PA1、PA2多克隆抗体的基础上，项目组证实UV-C照射虽未能改变4个MYB转录因子的表达规律，但其表达与结构基因表达呈现明显的正相关。.综上所述，UV-C照射未能影响黄烷醇类多酚和花色苷在葡萄果实发育过程中生物合成和积累规律，但具有一定的促进作用，且这一促进作用具有发育阶段性。因而，在葡萄果实发育过程中，定期或不定期施以UV-C照射，能够调控葡萄果实中黄烷醇类多酚和花色苷的生物合成与积累，促进黄烷醇类多酚和/或花色苷富集，从而人为调控葡萄果实乃至葡萄酒品质和保健功能。