黄瓜光敏色素CsphyB调控下胚轴长度的分子机理研究

黄瓜是我国重要的蔬菜作物，育苗移栽是黄瓜主要的栽培方式，下胚轴伸长导致的苗期徒长是育苗过程中常见的难题，但其调控基因和功能尚不明确。前期通过对长下胚轴双突变体WI7407L图位克隆，获得候选基因分别是光敏色素基因CsphyB和赤霉素20氧化酶基因CsGA20ox-2，具体调控的分子机理尚不清楚。本项目拟进一步采用基因表达、黄瓜遗传转化及表型观察验证CsphyB和CsGA20ox-2调控下胚轴伸长的基因功能；利用激素测定与外源激素处理研究CsphyB和CsGA20ox-2调控下胚轴伸长的生理机制；整合RNA-seq数据分析CsphyB和CsGA20ox-2在黄瓜下胚轴伸长过程的基因调控网络；同时借助酵母单杂筛库、蛋白互作等技术解析二者的调控方式。基于以上研究深入阐述CsphyB调控CsGA20ox-2参与下胚轴长度发育的分子机理，为选育下胚轴适度的黄瓜品种提供理论基础与基因资源。

Cucumber (Cucumis sativus L.) is one of the most important vegetables in China, and it is primarily transplanted with seedlings. Leggy seedling is a general problem for the production of cucumber seedling and caused by the rapid growth of hypocotyl. However, the key gene or gene network regulating the hypocotyl elongation and corresponding molecular mechanisms are largely unknown in cucumber. The spontaneous longer hypocotyl mutant WI7407L in the natural population of cucumber has been identified, which included two mutant locus and both of them were recessively inherited. Map-based cloning revealed that candidate gene an ortholog of Arabidopsis PHYTOCHROME (CsphyB), and GA20oxidase-2 (CsGA20ox-2), respectively, the molecular mechanism remains elusive. Thus, gene expression verifying, transgenic and phenotype analysis will be applied in order to investigate the gene function of CsphyB and CsGA20ox-2 in regulating the hypocotyl length in cucumber, then the physiological mechanism of CsphyB and CsGA20ox-2 on development of hypocotyl length will be studied by hormone measurement and treatment. Furthermore, we will use RNA-seq to analysis the gene regulating network during hypocotyl elongation in cucumber. Finally, the upstream regulatory genes of CsGA20ox-2 will be screened and verified by yeast one hybrid and then confirm the regulate correction between CsGA20ox-2 and CsphyB. The results will be important for important to reveal the molecular mechanism of CsGA20ox-2 regulated by CsphyB during hypocotyl elongation in cucumber. The results obtained in this project will provide the theoretical basis and gene resource for molecular breeding for cucumber seedling with optimum hypocotyl length.