沙棘果色形成和果实生长发育中非编码RNA调控的分子机制

Sea buckthorn (Hippophae rhamnoides L.) is an ecologically and economically important, globally distributed shrub tree, with yellow, orange or red berries containing abundant nutrition. Fruit color is one of the important properties of fruit quality, which depend on pigments element, such as carotenoid, anthocyanin and chlorophyll. At present, the study involved in carotenoid and anthocyanin biosynthetic genes was more, just like fruit growth and development. But noncoding RNA-based epigenetic regulation of gene expression, especially the long noncoding RNA (ncRNA), was absent. Based on previous transcriptome differences, this project will study the ncRNA and metabolites regulation of pigmentation and development in red- and yellow-fleshed Hippophae fruits, and find the genetic regulatory network associated with the biosynthesis of carotenoids, flavonoids and vitamin C. At the same time, this project will predict the unique ncRNA and their function, and clarify the regulation mechanism of noncoding RNA during fruit growth and color formation in sea buckthorn.

沙棘是生态效益和经济价值双优树种，其果实营养丰富，颜色以红、橙、黄为主，果实颜色是沙棘果实品质的重要指标之一。决定植物果色的色素主要有类胡萝卜素，花青素和叶绿素。目前对参与类胡萝卜素，花青素生物合成和果实生长发育基因的研究较多且比较成熟，而在基因表达调控，尤其是基于非编码RNA的表观遗传调控研究较少，特别是长链非编码RNA。本项目将在前期转录组差异研究的基础上，以沙棘不同生长发育时期的红果和黄果类型为研究对象，从表观遗传调控（非编码RNA调控）和代谢物反馈调控两个方面深入解析沙棘不同果色形成与生长发育机制，尤其是发现参与调控沙棘红、黄果色形成的类胡萝卜素、黄酮类和维生素C的合成与代谢过程相关基因的ncRNA和调控因子；建立沙棘ncRNA识别系统，并对预测的沙棘ncRNA进行功能分析，阐明ncRNA在沙棘生长发育和控制果色过程中的作用和意义。

果实成熟是由外源和内源因素共同调控的一个复杂的发育过程。沙棘果实富含多种生物活性成分和营养物质，广泛应用于各个领域。沙棘果实成熟过程中基因表达变化的研究比较清楚，但转录水平的非编码RNA(ncRNA)调控作用尚不清楚。本研究对沙棘不同发育时期果实的ncRNA (lncRNA、microRNA、cicroRNA)和mRNA高通量测序数据进行全面分析，鉴定和筛选出一批差异表达的ncRNA和mRNA，基于宿主基因功能注释，发现这些ncRNA可能参与沙棘果实类胡萝卜素、类黄酮、维生素C、脂质生物合成和植物激素信号转导。分别构建了lncRNA、microRNA、cicroRNA和mRNA互作网络，并通过设计6个circRNA背靠背特异引物的RT-PCR和克隆测序，以及2个lncRNA沉默和相应的RT-qPCR实验，初步验证了lncRNA和circRNA均能分别通过竞争性内源性模拟靶标(eTMs)的方式吸附microRNA，影响microRNA靶基因的表达，从而调控沙棘果实中生物活性成分和营养物质的合成和累积。本研究为理解沙棘果实生长发育和品质形成的ncRNA调控机制提供了重要证据。