濒危植物对节白蜡的繁育系统与遗传多样性研究

Fraxinus hupehensis, "the king of miniascape", only distributes in Dahongshan Mountains and neighboring areas at the junction of Zhongxiang County and Jingshan County of Hubei Province in China. The natural resources are extremely scarce and belong to a second-class state protected plants. Especially in recent years, the wild resources have been severely damaged by over-excavation because of its exploitation and utilization as potted landscapes. It is the urgent matter to understand the actualities of the germplasm resources and put forward the conservation strategy. In this project, some theories and methods from Plant Reproductive Ecology and Population Genetics will be carried out. Based on extensive investigation on the wild resources of Fraxinus hupehensis, its breeding system will be clarified by the analyses of the Out-crossing index, Pollen-ovule ratio, artificial pollination experiments and nSSRs of the speeds from the same plant; the level of genetic diversity, genetic structure, gene flow, population evolutionary history and population bottleneck effects of this species will also be detected using nSSR and cpSSR markers. According to the above results, the endangered mechanism, phylogeny and evolution of Fraxinus hupehensis will be argued and a conservation strategy will be proposed. Therefore, the results of this research will not only provide a scientific basis for the genetic management of Fraxinus hupehensis in ex situ and in situ and its population recovery, but also presented the foundation for further development and utilization, and genetic breeding of this endangered resource.

对节白蜡素有"盆景之王"的美称，特产于我国湖北省钟祥市与京山县交界的大洪山余脉及邻近地区，分布范围狭窄，资源稀少，属国家二级保护植物。尤其是近年来随着市场需求量的增加，野生资源受到过度采挖，破坏严重。本项目拟采用植物生殖生态学及居群遗传学的理论与方法，在全面调查对节白蜡野生资源的基础上，利用杂交指数、花粉-胚珠比、人工授粉实验及种子的nSSR分析等手段阐明其繁育系统；并利用 nSSR与cpSSR两种分子标记分析其遗传多样性水平、遗传结构、基因流、居群进化史，检测种群是否经历过瓶颈效应。综合繁育系统与遗传多样性的研究结果，探讨对节白蜡的濒危机制、系统发育与演化，并提出保育策略。本研究成果将为该物种在迁地和就地保护中的遗传管理和居群恢复提供科学依据，也为这一濒危资源的进一步开发利用及遗传育种研究奠定基础。

对节白蜡素有“盆景之王”的美称，特产于我国湖北省钟祥市与京山县交界的大洪山余脉及邻近地区，分布范围狭窄，资源稀少，且破坏严重，为国家二级保护植物。本项目对对节白蜡野生资源展开了全面深入的调查，摸清了现有资源的基本情况、生境条件及当地对该资源的栽培与保护情况等。并采集了10个自然居群196个单株的叶片，利用分子标记技术分别对核基因组和叶绿体基因组DNA进行了分析，掌握了对节白蜡遗传多样性及在居群内与居群间的分布规律，弄清了各居群的遗传分化程度、居群的遗传结构。本课题组还利用ITS和3个叶绿体psbA-trnH、rpl32-trnL及matK 标记对对节白蜡及其所在白蜡树属其它39个物种59个材料进行了谱系地理学方面的研究，结果表明对节白蜡最早分化于中新世中期 (11.87 Ma; 95% HPD: 5.79-19.42 Ma)，对节白蜡跟其所在组Sciadanthus 其它物种Fraxinus xanthoxyloides的间断分布与青藏高原和喜马拉雅的快速隆起有关。综合所有研究结果，进一步探讨了对节白蜡的濒危机制、系统发育与演化过程，并提出保育策略。本研究成果将为该物种在迁地和就地保护中的遗传管理和居群恢复提供科学依据，也为这一濒危资源的进一步开发利用及遗传育种研究奠定基础。