【作者】 孟祥春；

【导师】 王小菁；

【作者基本信息】 华南师范大学 ， 植物学， 2004， 博士

【摘要】 花器官决定之后，花器官各部分的生长和花色形成是花卉观赏品质形成的两大主要因素，受多种环境因素和发育信号的调控，其中光是最主要的外部调节因子。研究花生长和花色素苷积累的动态过程和调控机制对阐明花后期发育的机理具有重要的理论意义，可为如何提高花卉品质提供理论依据。 非洲菊（Gerbera Hybrida）是世界流行的五大切花之一，是研究复杂花序花发育的理想材料。本文将非洲菊花的后期发育过程分为6个时期（P1～P6），在建立花序和最外轮舌状花（ray floret，rf）离体培养系统的基础上，比较了花生长、花色素苷积累和CHS、DFR基因表达的动态变化；研究光对花瓣生长及花色素苷积累的影响和调控机理；对糖和GA₃影响花生长、花色素苷积累及CHS、DFR基因表达也进行了探讨。得到以下主要结果： 1、活体花序发育过程中，花生长与花色素苷积累同步增加，P6期花序完全开放时，花生长量最大，rf花瓣花色素苷含量在花刚开放时（P5）最高；rf花瓣的CHS、DFR基因表达的变化与花色素苷积累的变化趋势一致。 2、将P2期花序或rfs小花进行离体培养，在3％蔗糖+8g／L琼脂的培养基上，花序和rfs都可以生长和积累花色素苷，但花生长量和着色比活体条件下降低。离体花序和rfs的生长和着色必需有糖的存在。代谢性的蔗糖、葡萄糖和果糖对rfs花色素苷积累有效，非代谢性的甘露醇和山梨醇作用不明显。 3、活体花序在早期（P1、P2）被遮光后，花生长和rf花瓣花色素苷积累受到显著抑制；早期遮光后，在花发育后期去除遮光，不能恢复生长和着色。实验表明，光在花发育早期起关键作用，后期花的生长和着色对光的依赖性不大。在花序和rf的离体培养系统中，光对花色素苷积累的影响与活体系统中的结果相似。活体系统中光对花序和rf生长和花色素苷积累的影响呈显著相关，而离体系统中，相关性不明显。 4、活体系统中，P1期遮光后在P3期去遮光，CHS、DFR基因表达水平下降；在花序离体培养系统中，曝光可诱导rf花瓣的CHS、DFR基因表达，增加花色素苷积累；花序离体后暗培养超过3d，光的诱导能力逐渐减弱，说明对于花色素苷的积累和C月万、D尸况基因表达，存在最适宜的光诱导期。5、对活体和离体系统的rf花瓣中叶绿体结构进行观察。发现在花发育的P1、PZ期， if花瓣表皮细胞的叶绿体数目多，叶绿体结构完整;P3期叶绿体的基粒开始解体; 遮光或黑暗中叶绿体都发生解体的现象。光合作用抑制剂DCMU可抑制离体培养 的PZ期if花瓣花色素昔合成及C月污、刀不天基因表达。我们推测，光合作用可能仅 在花发育早期起作用;花发育后期，光主要通过光受体介导的光形态建成反应调节 花色素昔的积累。‘、不同光质的影响研究表明，蓝光对if花瓣中花色素昔积累及C祛夕、刀F况基因表达 的诱导作用最强。为了研究光受体的存在部位，我们将活体花序完全遮光，植株叶 片暴露在光下，花的生长和着色受到抑制;而将植株叶片完全遮光，花序暴露在光 下，花生长和着色可以进行;在活体或离体系统中，去除花序苞片也不影响花的生 长和着色;此外，rfs离体培养时，其生长和花色素昔积累同样受光的严格调控。 这些结果证明，对于光调控的非洲菊花色素昔积累，if本身是光信号的接收器官。7、离体花序和rf的正常生长和着色必需有光和糖同时存在，代谢性的蔗糖对花色素 昔积累的作用最大;GA3在花序培养中对花色素普积累无明显影响，而在rf培养 中，GA3仅在光下促进花色素昔积累。8、实验发现，在花序和rf的离体培养系统中，GA3明显促进if花瓣和表皮细胞的纵向伸长:光对if花瓣和表皮细胞的横向扩展和纵向生长伸长均有显著促进作用。更多还原

【Abstract】 After floral initiation and organ identity, the late developmental stage including flower growth and pigmentation is a key process contributing to the commercial characteristics of ornamental flowers. It is clear that the growth and anthocyanin accumulation in flower petals are regulated by environmental and developmental signals in which light is the most important environmental cue. In the present study, the changes of flower growth and anthocyanin accumulation and their photoregulation were investigated in Gerbera hybrida, one of the most popular five cut flowers in the world. In Gerbera, more than one morphological flower type exist in a single head-like inflorescence with many parameters varying in a single genotype, offering a unique model system in Asteraceae for studying inflorescence and flower development.Basing on our description of the six stages (P1-P6) of inflorescence development in Gerbera hybrida, in vitro experimental system was established to culture detached inflorescences and ray floret (rf). We compared the changes of flower growth, anthocyanin accumulation and CHS, DFR gene expression in vivo and in vitro and investigated the effect of light on flower growth and pigmentation. Additionally, the roles of sugar and GA3 in the process were also discussed. The major results are as follows:1. During inflorescence development, anthocyanin accumulation of rf petal coincided with the growth of the inflorescences and rfs in vivo. The fresh weight and size of inflorescences reached the maximum when flower was fully opened at P6, while pigmentation reached the highest level when inflorescence was half opened (P5). Changes of CHS and DFR gene expression were similar to that of anthocyanin accumulation during inflorescence development.2. Inflorescences and rfs were detached at the P2 and incubated on the sucrose medium (8 g/L agar with 3% sucrose), respectively. They could grow and accumulate anthocyanin on the medium during the culture time. However, the maximum level of the growth and pigmentation in vitro were lower than those in vivo. Sugar was required for detachedflower growth and pigmentation in vitro. Among various sugars tested, the metabolic sugars including sucrose, glucose and fructose showed effective in anthocyanin accumulation, while non-metabolic mannitol and sorbitol had no effect on pigmentation.3. When inflorescences were shaded with aluminum foil in vivo at the early developmental P1 and P2, anthocyanin accumulation and flower growth were dramatically inhibited; This inhibition could not be reversed when the shading was removed and the inflorescences were re-exposed to light at late stages. Our results demonstrated that light plays the key roles in flower growth and pigmentation only in the early stages of Gerbera flower development and it has a little role at the later developmental stages. Similar results in anthocyanin accumulation were obtained when inflorescences and rfs were cultured in vitro. There was a close relationship between light-regulated anthocyanin accumulation and flower growth in vivo and they had no significant correlation in vitro.4. When inflorescences were re-exposed to light at the P3 after shading at P1, the gene expression was down-regulated. Transient light exposure could induce CHS and DFR gene expression of rf petal when the inflorescences were cultured in vitro and the level of anthocyanin accumulation increased with the culture time after light treatment. The light induction of the gene expression decreased gradually when the pre-dark culture time was longer than 3 d. Our data demonstrated that there was an appropriate developmental time of the inflorescences responding to photoregulation of the anthocyanin accumulation both in vivo and in vitro.5. The ultrastructure of the plastids in rf petals were examined. Normal and intact chloroplasts were found in the P1 and P2 of flower development. They began to deteriorate at P3 and declined into chromoplast-like structure at P6; Similar results were obtained from inflorescences shaded更多还原