石竹属花卉重瓣花形成分子机理的研究

Double flower are one of the most important ornamental qualities of ornamental plants, and one of the major breeding goals pursued by breeders. Dianthus is a world famous ornamental plants, with high ornamental and economic value. To improve the double flower characteristic of Dianthus flowers can greatly enhance its ornamental quality and market value. The double flower trait is widely present in ornamental plants，but different from the double flowers generated through mutagenesis in model species. The genetics and molecular mechanisms for double flower in ornamental plants are poorly understood. In the current proposal, Dianthus cultivar with single-flower was crossed with double-flower cultivar, and a high generation of segregating population was constructed, in which the single/double flower trait showed a Mendelian ratio suggesting that the gene is controlled by a single gene. The petal trait was genetically mapped to a region of 10cM. We will fine map the candidate gene using a population of at least 4,000 individuals. We will also construct two pools (single flower pool and double flower pool), extract RNAs from the bud of the two pools and perform RNA-seq. Genes cosegregating with the petal trait will be identified and differentially expressed genes between the two pools will be identified as well. Above results will be used to determine the candidate gene controlling the petal trait. The candidate genes will be first tested using VIGS and real-time quantitative analysis. For complementation test, the best candidate gene will be transformed into single flower genotype. Then the verified gene will be studied for its expression profile, gene function analysis, regulatory pathway and downstream interaction proteins. Ultimately, our results will shed insights in the genetics and molecular mechanism of the double flower in Dianthus. The results are also critical for future breeding programs for Dianthus and may be useful for projects on double flowers in other ornamental plants.

重瓣性是观赏植物重要的观赏品质之一，也是主要育种目标之一。石竹属花卉为世界著名的观赏植物，具有极高的经济价值，提高石竹属花卉的重瓣性可大大提高其观赏品质和产值。但石竹属花卉重瓣花与模式植物的不尽相同，其形成机理至今尚不清楚。为探究其形成原因，前期我们对石竹的重瓣基因进行了初步定位，在绘制的高密度遗传连锁图谱上将重瓣控制基因定位在qDF-2位点上10cM范围内。为进一步缩小候选区域，明确重瓣控制基因，本项目将利用BC5分离群体进行重瓣基因精细定位，同时利用混池测序法来筛选重瓣控制位点和基因。进而利用VIGS、实时定量和转基因等方法进行重瓣候选基因的筛选和重瓣基因的确定。最后利用RNA-Seq、酵母双杂和BiFC等手段，来进行重瓣基因调控通路及互作蛋白等相关分析，明确重瓣基因调控通路。本研究将阐明石竹属花卉重瓣花形成的分子机理，为石竹属花卉品种改良提供重要的理论基础。

重瓣性是花卉非常重要的育种性状，为了明确石竹属植物重瓣花的形成机理，更好地了解石竹属植物重瓣性状形成的遗传机制，选择重瓣材料高代自交系的杂交F2代群体构建了高密度遗传图谱。根据器官发育特征，界定花器官发育阶段标准。利用香石竹拟测交群体、自交群体及中国石竹杂交群体，结合QTL定位、BSA分析、GWAS定位及转录组等多组学联合分析，筛选鉴定受miR172调控的A类基因APETALA2（DcAP2L）与石竹属植物重瓣性状有关，在花瓣原基和雄蕊原基时期，通过miR172结合位点不同程度的突变，使其蛋白水平高表达从而抑制DcAG基因的表达致使石竹属植物重瓣性状的形成。