Center for Viticulture and Enology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
Plant Physiol Biochem. 2012 Aug;57:74-83. doi: 10.1016/j.plaphy.2012.05.005. Epub 2012 May 12.
Modulation of flavonoid biosynthesis in grape berries has always aroused great attention among researchers. However, little study has been made on the shikimate pathway that guides photo-assimilate flow into flavonoid metabolism. The present study indicated that the treatments of three ultraviolet (UV) wavelengths differentially up-regulated transcriptional expression of some structural genes in the shikimate pathway and post-chorismate pathway of grape berries and this up-regulation was developmental stage-dependent and not synchronous. Of these genes, VvDAHPS-1 and VvDAHPS-2 encoding the entry enzymes of the shikimate pathway showed most significant UV-response and their transcription was strongly promoted by UV-A stimuli in the 3-week grapes and by UV-B and UV-C in the 7-week and 11-week grapes. The elevation of VvAS expression by UV induction appeared in the 3-week grapes and VvCM-1 was expressed relatively more concomitantly with berry mature. Correspondently, UV-B and UV-C irradiation increased the content of various anthocyanins in the 11-week grapes, but UV-A did not. These data suggest that UV-responsive production of anthocyanins is in part a consequence of the increase in carbon supply via promoting the shikimate pathway and the Phe/Trp specific pathway.
葡萄浆果中类黄酮生物合成的调控一直引起研究人员的极大关注。然而，关于引导光合同化物进入类黄酮代谢的莽草酸途径的研究甚少。本研究表明，三种紫外线（UV）波长的处理方式可使葡萄浆果中莽草酸途径和分支酸途径的一些结构基因的转录表达水平发生差异上调，这种上调具有发育阶段依赖性，不同步。在这些基因中，编码莽草酸途径起始酶的 VvDAHPS-1 和 VvDAHPS-2 表现出最显著的 UV 反应，其转录水平在 3 周龄葡萄中受 UV-A 刺激强烈促进，在 7 周龄和 11 周龄葡萄中受 UV-B 和 UV-C 刺激强烈促进。UV 诱导的 VvAS 表达的升高出现在 3 周龄葡萄中，并且 VvCM-1 的表达与浆果成熟相对更同步。相应地，UV-B 和 UV-C 照射增加了 11 周龄葡萄中各种花色苷的含量，但 UV-A 没有。这些数据表明，UV 响应产生的花色苷部分是通过促进莽草酸途径和苯丙氨酸/色氨酸特异性途径增加碳供应的结果。
