珍稀濒危木本药材厚朴繁育系统及其保护策略

Magnolia officinalis, were deemed to rare & endangered protection of the second specie, and traditional Chinese medicinal protection of the second plant. The valuable tree had been utilized in China for two thousand years. The medicinal materials magnitude of M. officinalis had overtaken 6700 t /y in China. Because of long collecting wild resources for supplying in medicinal, the wild resources of M. officinalis become smaller and smaller, being on the verge of drain, the surviving populations showed fragmented distribution, and the quality herbal medicine of plantation declined. All those seriously influenced the Genetic modified breeding, Subsequent breeding, and Sustainable use. On the basis of the study supported by Zhejiang province natural sciences fund key research project, this subject, used the wild-surviving populations of M. officinalis and Genetic changes of the Progeny groups of Control pollinations as a research object, trying to point the floral syndrome, hybrid abortion rate, and the pollination mechanism, study the type of breeding system of M. officinalis in fragmented distribution. This project will also study the genetic diversity and genetic differentiation among wild-populations of M. officinalis, the Progeny groups of Control pollinations between the parents with SSR molecular marker. Discussion on the relationship of the gene flow and genetic drift, so that the real causes of rare & endangered will reveal. Explaining clearly the positive role of breeding system and Control pollinations promotion gene exchanges, a reasonable conservation strategy will provide the scientific basis for excellent digging of wild germplasm and subsequent development.

厚朴为国家二级珍稀濒危保护树种和二级保护野生中药材，拥有2000多年药用历史，国内外每年用药量高达6700多吨。但因长期采集野生资源利用，厚朴野生资源量不断减少、野生资源濒临枯竭、残存群体呈现片断化分布、人工林药材质量下降，导致其遗传改育、后续育种和可持续利用受到严重影响。本课题在浙江省自然科学基金重点资助项目研究基础上，以厚朴野生残存群体和控制授粉的子代群体遗传变化为研究对象，试图从花部综合特征、杂交败育率、传粉机制等角度，研究片断化生境中厚朴繁育系统所属类型；应用SSR分子标记，揭示野生残存种群间、种群内和控制授粉子代群体间及其与母体间的遗传分化特征，探讨基因流与遗传漂变的相互关系，揭示厚朴濒危的真实肇因；阐明繁育系统和控制传粉对促进群体间基因交流的作用，提出合理的保育策略，为优良野生种质挖掘及后续开发利用提供科学依据。

厚朴为国家二级珍稀濒危保护树种和二级保护野生中药材，拥有2000多年药用历史，国内外每年用药量高达6700多吨。但因长期采集野生资源利用，厚朴野生资源量不断减少、野生资源濒临枯竭、残存群体呈现片断化分布、人工林药材质量下降，导致其遗传改育、后续育种和可持续利用受到严重影响。本项目以厚朴野生残存群体和控制授粉的子代群体遗传变化为研究对象，从花部综合特征、杂交败育率、传粉机制等角度，研究获知片断化生境中厚朴繁育系统所属类型为异交为主、部分自交亲和的混合交配系统。研究建立了SSR分子标记技术体系；揭示厚朴遗传多样性高低顺序为杂交子代（I=1.4544，Nei=0.7193，He=0.7287）>杂交亲本（I=1.3958， Nei=0.6899 ，He=0.6955）>自由授粉子代（I=1.2118，Nei=0.6423，He=0.5910），杂交子代遗传多样性水平显著高于自由授粉子代；自由授粉子代群体表现为纯合子过剩而杂合子明显不足，即自由授粉子代可能存在较高程度的近交；亲本间遗传距离与杂交子代遗传多样性之间呈正相关，但相关性未达到显著水平（R=0.3924）；根据Nei遗传距离对亲本及子代进行UPGMA聚类，发现杂交子代与父本亲缘关系更近。研究揭示出厚朴混合交配的繁育系统、持续开花模式、授粉昆虫过少、离心心皮败育率极高等共同构成了濒危的真实肇因。厚朴繁育系统不利于花粉在种群间传递，群体遗传多样性会越来越低，濒危处境愈发严峻；人为控制授粉能促进其群体间基因交流，拓宽了群体遗传基础，利于种群遗传多样性恢复，这是厚朴资源保育的重要策略。研究结果为厚朴优良种质资源挖掘、后续开发利用及衰退物种遗传多样性恢复和种群重建提供科学依据。