调节果穗曝光改变葡萄多酚组成及葡萄酒颜色稳定性的机制研究

The grape skins and fresh wines produced in Xinjiang region generally show perfect coloration as a result of strong sunshine, great mperature difference and less rainfall. However, the color in wine is quickly faded in the process of aging. Therefore, how to retain wine color is a key problem that should be urgently solved in the production of high-quality wines in this region. Based on the previous research findings about co-pigmentation function of grape non-anthocyanin phenols and the effects of these compounds on wine color stability, this project intends to take light as a breakthrough point. By selecting vineyards and altering the light intensity around berry cluster through the treatments of shading, we focus our study on the effects of light-intensity alteration on the accumulation of various non-anthocyanins and anthocyanins, and the expression of the important genes involved in the phenylpropanes - flavonoid metabolism of grape berries, as well as the color-related compounds and color stability in the wines produced from these grapes. The results will determine the critical components affecting the wine color stability, and expound a light-regulatory mechanism of carbon allocation in the phenylpropanes-flavonoid metabolism. This work will provide a theoretical basis for fundamentally controlling the light radiation by cultivation means to promote reasonable carbon flow in the flavonoid metabolism pathway, to thus ensure the production of adequate non-anthocyanin components, and to improve color stability of regional wines. Also this work will lay a good foundation for the future exploration of the molecular mechanism underlying the regulation of flavonoid metabolism in grapes in Xinjiang region.

由于新疆地区光照强、温差大、降雨少的气候特点，所生产的葡萄果皮乃至新鲜葡萄酒呈色都较深，但随着葡萄酒的陈酿，颜色迅速褪化。如何保持葡萄酒颜色稳定性是该地区优质红葡萄酒生产急需解决的问题。基于前人对葡萄果实中非花色苷酚类物质的辅色效应及其对葡萄酒颜色稳定影响的研究成果，本项目拟以光照为切入点，选取新疆地区典型生态区域的葡萄园，通过果际遮阴处理调节果际光照强度，研究其对葡萄果皮苯丙烷-类黄酮代谢中各种非花色苷酚和花色苷积累、相关基因表达以及对相应葡萄酒颜色稳定的影响，明确导致新疆地产葡萄酒颜色不稳定的关键组分，阐明光对果实苯丙烷-类黄酮代谢流向的调节，为通过栽培手段从根本上调控光合同化物在苯丙烷-类黄酮代谢中合理分配以保证足量非花色苷酚辅色组分的产生、促进葡萄酒色泽稳定性的提高提供理论依据，也为后续深入探究光对类黄酮代谢流向调控的分子机理奠定基础。

本项目从光照为切入点，选取新疆地区典型生态区域的葡萄园，连续两年在葡萄果实的不同生长发育阶段分别使用两种遮阳网进行树体遮光。利用高效液相色谱—质谱法（HPLC-MS）检测了不同发育时期葡萄果实及葡萄酒中酚类物质的含量，分析葡萄酒的色泽稳定性，并采用转录组学分析葡萄果实在发育过程中苯丙烷-类黄酮代谢路径主要基因的相对表达情况，明确导致新疆地产葡萄酒颜色不稳定的关键组分，阐明光对果实苯丙烷-类黄酮代谢流向的调节，为通过栽培手段从根本上调控光合同化物在苯丙烷-类黄酮代谢中合理分配以保证足量非花色苷酚辅色组分的产生，从而促进葡萄酒色泽稳定性的提高提供理论依据，实验结果如下：. 本研究采用两针普通型（网1），三针加密型（网2）的黑色单层遮阳网对树体顶端进行遮光，使得果际周围的光合有效辐射分别降低了20%、50%，但对果际周围的温度、湿度并无明显影响。遮光处理延长了果实的物候期，但对果实中的总酸、pH无明显影响。. 遮光处理降低了葡萄果皮中花色苷类物质的总量；使用网2有效提高了成熟果实果皮中甲基化花色苷、香豆酰化花色苷的比例；同时当葡萄果实开始转色时采用网2 进行的遮光处理提高了非花色苷酚类物质的积累，主要影响了槲皮素-3-O-葡萄糖苷、槲皮素-3-O-葡萄糖苷酸、杨梅酮、丁香亭-3-O-半乳糖苷几种物质。. 对苯丙烷-类黄酮代谢路径中的相关基因进行转录组学测序分析，结果显示于葡萄果实开始转色时采用网1、网2 进行的遮光处理提高了参与黄烷-3-醇及黄酮醇类物质合成的FLS、LAR1、LAR2基因的表达，同时提高了F3’H流向物质的表达。. 对葡萄酒样品进行分析发现，遮光处理后葡萄酒样品中具有高亮度，红色色调、黄色色调表现性低的特征；同时，遮光处理显著提升了葡萄酒样品中非花色苷酚类物质的积累。