濒危羊踯躅片断化居群遗传多样性的维持机制及保育策略

In China, Rhododendron molle is the unique species of Subgenus Pentanthera in Andromeda, which has high economic and medicinal value. Its wild populations have been severely fragmented due to the disturbance of human activities. The remnant populations are exposed to higher risk of critically endangered or extinction. Therefore, studies on the conservation genetics should be urgently carried out to rescue the endangered genus. . Based on our previous researches, SSR and AFLP molecular marker will be used to investigate the distribution pattern, genetic diversity, genetic structure, gene flow and reproductive fitness of R. molle, of which underwent sverrely habitat fragmentation, in several different province. These detailed results will be very helpful for identifying the superior conservation of R. molle, illuminating the impact of habitat fragmentation on the genetic aftereffect and its action mechanism for R. molle. Furthermore, the maintenance mechanisms of genetic structure and diversity of endangered R. molle in fragmental population will be assessed in detail. On this condition, sampling strategy of biodiversity as well as the suitable in situ or ex-situation conservation strategy was established through computer simulation of random sampling methods. For these unfavorable to germination or growth, micropropagation and reintroduction system will be estalished to protect the endangered R. molle. Our results of this study are very useful for detecting the maintenance mechanism of genetic diversity in R. molle and its endangered mechanism. It would also provide scientific basis for in situ conservation recovery, ex situ conservation management, and seed resource selection of reintroduction. There is a very important theoretical and practical significance on sustainable utilization for R. molle.

羊踯躅是我国杜鹃花科羊踯躅亚属中仅有的一个原生种，具有极大的经济价值和药用价值。由于人们长期过度采集和挖掘，羊踯躅生境出现严重片断化，其濒危或灭绝的风险日益加剧，亟待开展保护遗传学研究。 . 本项目基于我们的前期研究基础，进一步在多个省份调查取样，采用SSR和AFLP分子标记，研究查明羊踯躅经历严重片断化后的分布格局、遗传结构特征和多样性水平，当前花粉基因流和生殖适合度特征，确定该物种的优先保护群体；阐明生境片断化对该物种的遗传后果及作用机制；深入探讨濒危羊踯躅片断化居群遗传多样性和遗传结构的维持机制。在此基础上，通过计算机模拟随机取样建立基因捕获曲线，构建羊踯躅就地和迁地保护的取样策略；对不利于种子萌发和幼苗生长的居群进行克隆繁殖和回归定植。本研究为揭示羊踯躅致危机理提供理论依据，为濒危羊踯躅的就地或迁地保护的遗传管理及回归引种的种源选择和配置提供指导，具有十分重要的理论和实践意义。

羊踯躅（Rhododendron molle G. Don）是中国杜鹃花科羊踯躅亚属仅有的一个原生种，不仅是杜鹃花色品种改良的重要资源，而且具有重要的药用价值和经济价值。由于人们长期过度采集和挖掘，羊踯躅栖息地遭到破坏，其生境出现严重片断化，部分地区野外已难见其踪影，羊踯躅濒于灭绝的风险日益加剧，亟待加以保护。. 本项目对6省8个羊踯躅自然居群进行调查取样，利用RAD-seq技术开发了羊踯躅11,961个SSR标记，随后利用多态性SSR标记分析了羊踯躅片断化后的遗传结构特征和多样性水平。物种水平的Shannon多样性指数（I）为1.768，基因多样性指数（H）为0.777。江西金溪的羊踯躅居群的遗传变异最丰富，福建政和的遗传多样性水平最低。基于无限等位基因模型（IAM）的遗传分化系数（Fst）为0.142，基因流（Nm）为1.522；AMOVA分析显示羊踯躅居群内变异（87.71%）大于居群间变异（12.29%）。Mantel检测发现，羊踯躅遗传距离与地理距离无显著相关性。羊踯躅最好以就地保护为主，应优先保护金溪，同时增加对政和和京山居群的保护权重。随后本项目成功建立了金溪、政和以及永修三个居群的离体繁殖体系。用多重灭菌法对羊踯躅新生腋芽进行表面灭菌其结果表明外植体污染率低于10%。新生腋芽在改良的6,7-V + ZT（玉米素）1.0 mg/ L上生长快，长势好。不定芽在培养基（6, 7-V + ZT 1.0 mg/ L）上的增殖效果最好。研究结果对羊踯躅的保护和利用具有重要的理论和实践意义。. 另外，利用MTT实验对羊踯躅不同组织器官对肺癌细胞的抑制作用进行研究，发现羊踯躅茎对肺癌细胞A549的抑制效果最好。抑菌性研究发现羊踯躅的不同器官都有一定的抑菌效果，其中羊踯躅叶对大肠杆菌、金黄色葡萄球菌、考克氏菌敏感性最强。为羊踯躅的开发利用奠定了重要基础。