低温与赤霉素调控秋发牡丹成花的分子机理

Tree peony is not only one of the most important ornamental crops, but also the first candidate for Chinese national flower. However, industrial production is greatly limited due to its relative short and concentrated flowering period. The special cultivars with forcing culture can be achieved for the full year flowering. In this study, ‘Qiu Fa Yi Hao’, which is sensitive to low temperature and gibberellin (GA) in our previous study, will be used as the material to investigate molecular mechanism of flowering regulation of tree peony, and the traditional cultivar ‘Luo Yang Hong’ is used as control material. Key flowering genes (viz. FLC, DELLA etc.) which are easily affected by low temperature and GA will be isolated with rapid amplification of cDNA ends (RACE) method, and the genetic regulatory networks will be carried out in different cultivars on different developmental stages. Then the gene function will be identified by Arabidopsis genetic transformation. At the same time, the method of epigenetics is used to isolate genome sequence which is easily methylated, and determine the methylated sites of the flowering genes such as FLC. Finally, combined with the physiology changes and morphological characteristics with different low temperature and GA treatments, the molecular mechanism of flowering regulation for autumn-flowering tree peony will be deciphered, which will provide theoretical basis for improving forcing culture and the breeding of year-round cultivars.

牡丹是我国的传统名花，也是重要的候选国花，但自然花期短且相对集中，限制了其产业化生产。采用特定品种进行花期调控，可实现牡丹的周年供花。本研究以前期研究中获得的对低温和赤霉素敏感、易于秋季成花的牡丹品种‘秋发一号’为材料，并以常规促成栽培品种‘洛阳红’为对照，针对低温与赤霉素这两大影响牡丹成花调控的重要因素，利用已有转录组数据结合RACE技术，发掘与低温及赤霉素调控相关的FLC、DELLA等成花关键基因，研究其在不同牡丹品种、不同成花阶段的网络调控差异；通过转化拟南芥，验证牡丹关键成花基因的功能；同时利用表观遗传学方法，分离与甲基化密切相关的基因组序列，研究FLC等成花基因的甲基化位点，明确DNA甲基化与牡丹成花的关系，最后综合上述研究结果及低温与赤霉素处理对牡丹生理生化及表型的影响，揭示秋发牡丹易于成花的分子调控机制。本研究可为提高牡丹促成栽培效率、培育四季开花牡丹品种提供理论依据。

牡丹是我国的传统名花，也是重要的候选国花，但自然花期短且相对集中，限制了其产业化生产。采用特定品种进行花期调控，可实现牡丹的周年供花。本研究选择易于秋季开花的‘秋发一号’牡丹和对照品种‘洛阳红’为实验材料，探讨了低温和赤霉素处理调控秋发牡丹二次开花的分子机理。共筛选得到关键二次开花基因10个，提出了诱导牡丹成花的5条途径；发现低温、脱叶和赤霉素等处理可促进秋发牡丹花芽分化和生长发育，并影响内源赤霉素、生长素、脱落酸等激素含量变化调控牡丹成花；赤霉素合成和信号转导基因在牡丹中高度保守，PsCPS、PsGA3ox、PsGA2ox、PsGID1、PsDELLA、PsGID2等基因可以反馈调节内源赤霉素的含量；‘洛阳红’牡丹对低温需求量大，完成花芽休眠解除‘洛阳红’牡丹的成花调控机理与秋发牡丹类似；3种处理方式还可通过影响花芽和花器官中非结构性糖的分布来调控牡丹成花，但‘秋发一号’和‘洛阳红’牡丹参与蔗糖转运的具体调控基因不同。本研究为提高牡丹促成栽培效率、培育四季开花牡丹品种提供理论依据。