流苏野生居群的遗传多样性及繁殖生物学特性研究

Chionanthus retusus Lindl et Paxt is a tree species of Oleaceae with landscaping, ornamental, medicinal, tea-making and many other practical value. It has been eagerly sought as the best rootstock of osmanthus fragrans on the landscaping market in recent years. C. retusus has been seriously damaged in the nature population because of the excessive use and lack of protection. It is unknown whether C. retusus is functionally or mere morphologically androdioecious. This research intends to carry out a comprehensive census and resource collection of existing nature populations of C. retusus, and then examine the population structure and genetic variation according to the results of population morphological investigation and the SSR analysis and cpDNA molecular techniques. To discover the essence of breeding system, study on reproductive biology will be carried out on several wild C. retusus populations by comparing flowering biology characteristics and conducting artificial pollination experiments. The degree of C. retusus threatened can be evaluated according to clear of the key point and limit factors in the process of reproduction and the genetic diversity. The reasonable utilization and protection strategy would be put forward. The results of the study will provide important theoretical basis for understanding the distribution of existing resources, breeding systems and genetic structure of nature population, but also provide a scientific guidance to make rational use and protection strategies for the relevant departments.

流苏是木犀科流苏树属植物，具绿化、观赏、制茶、入药等多种价值。作为嫁接桂花最理想的砧木，流苏近年来在园林绿化市场供不应求。重利用而轻保护，造成流苏野生资源的灭绝性毁坏；流苏是功能的雄全异株还是形态的雄全异株尚不清楚。本项目拟通过对现存流苏野生资源进行全面普查和资源收集，利用SSR和cpDNA分子技术，从形态学、核基因组和叶绿体基因组综合分析流苏野生居群的组成，遗传结构。选取若干居群定点开展繁殖生物学研究，通过流苏的开花习性，单性与两性花的花粉活力比较，柱头可授性分析，人工授粉杂交试验等，揭示流苏雄全异株的繁育本质。通过流苏繁殖过程中的关键环节和限制因素的明确，结合遗传多样性分析，评估流苏受威胁的程度，并提出合理利用和保护策略。研究结果不仅全面系统的了解现存流苏野生资源的分布状况、遗传结构和繁育本质，也能为相关部门评估流苏受威胁的程度提供科学依据，为制定合理的资源利用与保护策略提供方法指导.

流苏树属木犀科流苏树属，拥有罕见的雄全异株系统，但其生殖特性尚不明确，基础理论研究薄弱。近些年来，流苏树被过度开发利用，野生种质资源遭到严重破坏。.本项目通过野外观察和人工授粉实验对其传粉生物学特性进行研究。结果表明：流苏树雄花和两性花的花粉粒都具有活力，靠风和昆虫（蓟马和食蚜蝇）传粉。控制授粉30d后，自然对照结实率为34.36％；两性花不存在无融合生殖现象；自交亲和，但自发自交的结实率仅10.70%；人工授粉下杂交结实率显著高于自交；属于混合交配系统。证实流苏树是功能性的雄全异株。.选取地理分布较远的3个流苏树样本进行测序。以油橄榄叶绿体全基因组为参考序列，经过拼接、比对和注释，组装成流苏树叶绿体全基因组。对3个基因组序列全长比对，筛选出两个变异相对较大的基因间隔区片段。.利用筛选的cpDNA片段和核基因组SSR标记，分析中国32个流苏树野生居群的272份材料。cpDNA片段确定出7个单倍型，单倍型多样性为 0.631，核苷酸多样性为 1.49×10-3。单倍型的地理分布确定江西省为其遗传多样中心。SSR分析出基因多样性为 0.692，其遗传多样性水平要低于中国分布的大多数种子植物。无论是cpDNA还是核基因组分析，流苏树的遗传多样性都处于较低的水平。河南、湖北到江西一带的流苏树野生资源是优先保护群体，而含有特有单倍型或特有基因型的居群则是重点保护对象。