云南梧桐(Firmiana major)的变色花传粉功能特征及遗传结构研究

	云南梧桐(Firmiana major)的变色花传粉功能特征及遗传结构研究
	马雨倩
导师	孙卫邦
关键词	云南梧桐，极小种群野生植物，遗传结构，花色变化，传粉特征 Firmiana major Plant Species with Extremely Small Populations Genetic structure Floral color change Pollination characteristics
摘要	云南梧桐（Firmiana major (W.W.Smith) Hand.-Mazz.) 属于锦葵（Malvaceae）梧桐属（Firmiana Marsili），是中国特有的国家二级重点保护植物，也是我国西南地区金沙江流域河谷型稀树草原植被（Savanna）中优势、甚至是唯一大型叶乔木树种。之前对金沙江流域调查中发现了 14 个云南梧桐分布点，总数不超过5000 株。该物种被列入《云南省极小种群野生植物保护名录（2021 版）》中，亟待实施抢救性保护。本论文基于李聪佳博士对云南梧桐保护生物学的研究基础，对云南梧桐种群现状、繁殖生物学特性和遗传结构进行深入研究。主要研究结果如下： 1.云南梧桐变色花的传粉特性探究云南梧桐的花寿命约两天。花在刚刚开放时呈现黄色，在开放后 12 小时后转为橘色，并在开放后 18 小时后转为淡红色，之后花朵颜色逐渐加深。在云南梧桐的花变色过程中，在蜂类视角下雄花的颜色变化较大，雌雄花的醒目程度均随颜色变化逐渐下降。传粉者选择偏好观察发现，植株花序总花量和开放花量对传粉者访问和停留的时长没有影响；传粉者偏好访问黄色雄花，访问黄色雄花次数和停留时长均大于雌花，且在花朵黄色时期上停留的时间比红色时期长。对云南梧桐传粉生物学特性研究发现，黄色花期间的花粉活力、柱头可授性、花蜜供给和花气味释放量均高于红色花期间。云南梧桐花色和气味是吸引传粉者访问的信号，传粉者可能通过访问黄色花和红色花获得的不同花蜜量，训练了其访问黄色偏好，从而提示有经验传粉者更多的访问黄色花，增加访花效率。花粉限制指数表明了云南梧桐存在显著的花粉限制现象。云南梧桐的主要呈色物质应是类黄酮和花青素，花朵由黄变红的过程是因为花青素物质的合成和积累。转录组分析中，从苯丙烷合成通路和类黄酮合成通路中共筛选出 17 个参与了花色变化的候选基因。 2. 云南梧桐的保护遗传学研究本研究新发现两个云南梧桐种群共 1865 株，均位于保护区外，无任何保护措施，人为干扰严重。加入新种群分子材料后，对云南梧桐的保护遗传学特征重新分析的结果表明：云南梧桐的物种遗传多样性处于中等水平（He = 0.653）；所有种群近期均经历过瓶颈效应；云南梧桐的主要传粉者是木蜂属（Xylocopa）和无垫蜂属（Amegilla），赤腹松鼠（Callosciurus erythraeus）应该是其种子的传播者，其传粉距离和种子传播距离有限。云南梧桐的 8 个野生种群被划分为 4 个遗传单元，近似贝叶斯计算（Approximate Bayesian Computation，ABC）分析表明云南梧桐的 4 个遗传单元的分化时间均与末次冰期的暖期（88000–71000 年前，45000–22000 年前）有关，最后分化的种群遭遇瓶颈的时间刚好与人类从横断山脉地区南迁至喜马拉雅山的时间相吻合（6560 年前）。对云南梧桐的潜在分布区进行模拟，发现其潜在分布区域仅包括元谋盆地、金沙江干热河谷及其邻近的干热气候地区。对种群间以及遗传单元之间的生态位分化进行检测，结果表明虽然云南梧桐种群间和遗传单元间没有发生生态位分化，但其存在一定的生境适应差异。 3. 综合保护策略基于研究结果，在建立保护小区的基础上，本研究还提出了以下针对性的保护建议：（1）保护当地的传粉者和种子传播者，例如目前在各种群分布地日益减少的木蜂，提倡当地居民驯养木蜂，不仅能促进云南梧桐的传粉，并且可以产生一定经济效益。（2）基于有效种群大小（NE）制定种群恢复目标。建议云南梧桐小种群的种群恢复应该以达到其 NE 值至少高 10 倍的种群规模为目标，从而维持遗传健康和进化潜力。通过将该物种作为本地绿化物种引入生态恢复项目和植树造林，可实现种群恢复的更高目标，塑造健康种群。（3）对云南梧桐进行遗传拯救。针对当前云南梧桐的 NE 值较低的情况，所有种群都应得到重视，特别是对于 NE 值小于 50 的种群进行遗传拯救。通过在遗传相似性较远或空间距离较远的个体间进行人工授粉，从而完成遗传拯救。; Firmiana major (W. W. Smith) Hand. -Mazz. is a plant of the genus Firmiana Marsili (Malvaceae). F. major is a national secondary protective plant endemic to China, and it is also the dominant tree species in Savanna vegetation of arid hot valley, Jinsha River, southwest China. In the previous investigation of the Jinsha River, 14 localities of F. major were found, with a total number of no more than 5,000 individuals. F. major was listed in the List of Yunnan Protected Plant Species with Extremely Small Populations (2021 Edition) and urgently need rescue conservation. Based on the previous research, this study conducted in-depth research on the population situation, reproductive biological characteristics and genetic structure of F. major. The main results are as follows: 1. Pollination characteristics of floral color change of F. major The floral longevity of single flower of F. major is only two days. The flower color is yellow when it just opened; 12 hours after opening, the color turned orange; it turned to light red after 18 hours of opening, and then the color gradually became darker. From the pollinators’ perspective, the color change of male flowers was larger than that of female flowers and pollinated female flowers, and the visibility of flowers gradually decreased from the time when the flowers just open. The study on pollinator selection preference found that the total number of flowers (including buds) and the number of open flowers did not affect the pollinators' choice to visit and residence time; pollinators preferred to visit yellow and male flowers, and stayed longer on yellow flowers than red flowers. The research on the pollination function of the color-changing flowers of F. major showed that the pollen vitality, stigma receptivity, nectar supply for pollinators and floral odor release during the yellow flower period were higher than those during the red flower period, indicating that its pollination efficiency was higher. The flower color and odor of F. major are the signals that attract pollinators to visit. Pollinators may obtain different amounts of nectar by visiting yellow flowers and red flowers. Its preference for visiting yellow flowers was trained, thereby warning experienced pollinators to visit more yellow flowers, which increases the efficiency of pollination. The pollen restriction index verified the existence of significant pollen restriction phenomenon in F. major. The analysis of flower pigments showed that the main pigment of F. major were flavonoids and anthocyanins, and the process of changing from yellow to red was due to the synthesis and accumulation of anthocyanins. In transcriptome analysis of color- changing petals of F. major, Phenylpropanoid biosynthesis and Flavonoid biosynthesis were found to be related to color changes, and a total of 17 candidate genes involved in color change were screened out.
语种	中文
	2022-05
学位授予单位	中国科学院大学
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/75178
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	马雨倩. 云南梧桐(Firmiana major)的变色花传粉功能特征及遗传结构研究[D]. 中国科学院大学,2022.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
马雨倩-云南梧桐297e9f97-41c（5297KB）	学位论文		限制开放	CC BY-NC-SA	请求全文