果实发育是果树作物中最为重要的生物学过程之一。植物激素赤霉素（GA）在这一过程中有着极其重要的调控作用。申请人前期研究发现miR482/2118很可能通过介导phasiRNA的产生参与GA信号转录，进而调控荔枝果实生长发育。目前有关于miRNA直接参与GA信号转导的调控通路在植物中尚未有报道。为进一步解析这一调控通路在果实发育过程中的作用机理，本项目拟从三个方面开展研究：（1）调控通路中关键基因及上下游调控因子的鉴定及调控网络分析；（2）两个荔枝品种（‘怀枝’和‘糯米糍’）果实发育过程中，这一通路时空调控模式的对比研究；（3）关键小RNA（miR482/2118和phasiRNA）和关键调控基因行使功能的细胞学基础。上述研究结果既可以丰富植物miRNA作用和GA信号转导调控相关理论，又有助于解析GA信号转导影响荔枝果实发育的分子机理，为生产上更好地利用赤霉素这一植物生长调节剂提供理论支持。

Fruit development is one of the most important biological processes of fruit trees. Gibberellin (GA) plays pivotal roles in this process. Our preliminary research results in litchi have revealed that miR428/2118 is involved the GA signaling pathway via the instigation of phasiRNA production, likely playing an important role in the fruit development. So far there is no report about the direct involvement of a miRNA in the GA signaling pathway. To verify and study in detail the role of this regulatory pathway in litchi fruit development, this project is set out to carry out studies of three major parts: (1) genome-wide identification and regulatory network exploration of keys genes of the pathway and their upstream and downstream regulators; (2) profiling the spatiotemporal regulation pattern of the pathway in the fruit development of two litchi cultivars, ‘Huaizhi’ and ‘Nuomici’; (3) investigating the cellular basis for the function of small RNAs (miR482/2118 and phasiRNA) and keys genes in the regulatory pathway. All the results obtained from this project will greatly enrich our knowledge about miRNA function and GA signaling in plants, and will also shed new light on the role of GA signal in the development of litchi fruit, helpful for the development of improved approaches of using the plant growth regulator GA in fruit production.