光在不同色泽樱桃果实着色中的作用及其机理研究

The accumulation of anthocyanin pigments in sweet cherry (Prunus avium L.) fruit is an important determinant of fruit quality. The color of the fruits can be divided into red and bicolored varieties, and differences in the levels of anthocyanins vary between cherries of different colors. Light is one of the most important environmental factors that influence the biosynthesis of anthocyanins. Our previous work has proved that light exclusion reduces the anthocyanin content in the fruits of red sweet cherry cultivars, but inhibits its synthesis in bicolored cultivars, which suggests that light may regulate fruit coloration by interacting with other signaling pathways. To clarify the transcriptional regulatory mechanisms controlling the fruit coloration in sweet cherry, red fruit cultivar ‘Hong deng’ and the bicolored cultivar ‘Rainier’ are used as the experimental materials to establish a database of transcriptome sequences of sweet cherry fruit. The transcriptome database was used as reference data to identify candidate key transcription factors involved in the coordinate regulation of the anthocyanin biosynthesis by light and hormone signals. Based on this, VIGS and protoplast transformation assays will be performed to characterize the biological function of candidate genes. Meanwhile, various molecular technologies will be conducted to determine the pathway of light-induced and hormone-mediated anthocyanin biosynthesis. This study aims to elucidate the mechanism and pathway by which light influences anthocyanin biosynthesis and fruit coloration in different cultivars of sweet cherry.

花色苷的积累水平直接决定甜樱桃果实的色泽品质。根据成熟时的果实色泽，甜樱桃可分为红色和黄色品种。光是影响花色苷合成的最重要的环境因素之一，我们的研究显示，套袋仅减少红色品种果实中矢车菊素-3-O-芸香苷的含量，却可以完全抑制黄色品种果实中该成分的合成，暗示光在不同色泽果实着色中的具体调控机制不同。结合以往报道与本课题组的研究，ABA和IAA在果实着色中亦起重要作用，但三者在樱桃果实着色尤其是不同色泽果实着色调控中的相互关系尚不清楚。为此，本研究拟以不同色泽樱桃果实为试材，利用RNA-Seq深入挖掘参与光和激素信号协同调控果实色泽形成的核心转录因子；通过VIGS和原生质体转化明确其功能；进而结合Y2H、BiFC和EMSA等技术，确定关键转录因子的上下游信号组分及调控网络，以此解析光、ABA和IAA三者在不同色泽樱桃果实着色中的交叉对话，并最终揭示不同色泽樱桃果实着色的分子机理。

花色苷的积累水平直接决定甜樱桃果实的外观品质，而光是影响花色苷合成的重要环境因素之一。本研究以不同色泽甜樱桃果实为试材进行套袋和激素处理，结果发现ABA是调控以‘红灯’为代表红色品种着色的关键因素，光是调控以‘雷尼’为代表的黄色甜樱桃果实着色的关键因素，ABA也可促进‘雷尼’果实着色，且高度依赖于光。对光调控‘雷尼’果实着色分子机理的研究发现，PacCHS、PacCHI及PacUFGT等花色苷合成关键基因对光信号响应的敏感度不同是品种间着色机理差异的分子基础。综合药理学处理和转录组、基因表达及生物信息学分析，筛选光调控黄色品种着色的转录因子，发现32个上调和40个下调的转录因子特异性受光诱导表达，其中PacHY5和PacMYBA受光特异性表达最显著。进一步分析重要转录因子调控结构基因光响应特性中发现，PacUFGT受光特异性表达最显著；PacHY5和PacMYBA能直接调控PacUFGT启动子的表达。为揭示光信号转导调控花色苷合成机理，筛选了关键转录因子的互作蛋白，发现PacHY5和PacBBX9在细胞核内互作，且两者协同增强花色苷合成调控相关基因PacMYBA启动子的表达。以上结果表明“BBX9-HY5-MYBA-UFGT”信号模块是调控光诱导黄色甜樱桃果实花色苷合成的关键途径。此外，光可诱导‘雷尼’果实中ABA，BR和GA含量显著上调，推测光可通过影响ABA、BR和GA信号通路调控花色苷合成。综上，本研究揭示了光是调控以‘雷尼’为代表黄色樱桃果实着色的关键因素，明确了调控光诱导‘雷尼’果实着色的关键结构基因和重要转录因子，解析了“BBX9-HY5-MYBA-UFGT”信号模块调控果实着色的分子机理，为系统阐明光诱导甜樱桃花色苷合成的作用机制奠定了基础。项目组织管理规范，经费支出合理；共发表SCI 6篇，获国家发明专利授权1项；培养研究生6名；圆满完成项目各项任务指标。