山莨菪的保护遗传学研究

NWIPB OpenIR

	山莨菪的保护遗传学研究
其他题名	Conservation genetics of Anisodus tanguticus (Solanaceae)
	郑伟
学位类型	博士
导师	刘建全
	2009-05-25
学位授予单位	中国科学院西北高原生物研究所
学位授予地点	西北高原生物研究所
关键词	山莨菪保护遗传学遗传多样性青藏高原遗传分化
摘要	山莨菪(Anisodus tanguticus (Maxinowicz) Pascher)是茄科(Solanaceae)山莨菪属一种多年生草本植物，是我国特有种，常见于青藏高原及邻近地区。山莨菪富含莨菪碱和东莨菪碱等，是一种重要的药用植物，但由于人类的过度才采挖，于1990年被列为二级濒危植物。为实现山莨菪药用价值的可持续发展和保护我国特有种质资源，本文在山莨菪主要分布区广泛采样的基础上，结合RAPD分析方法，首次对该植物进行了遗传多样性分析，并在次基础上探讨了其保护策略。本文使用RAPD标记技术对山莨菪居群的遗传多样性和遗传分化进行了研究，利用12条随机引物对其主要分布区的10个居群181个个体进行扩增，共检测到92个位点，其中76个是多态性位点，物种水平上的多态性位点比率(PPB)为82.61%。POPGENE软件计算，居群总的遗传多样性和Shannon多样性指数分别为0.3015和0.4459，显示较高水平的遗传多样性。居群内的遗传多样性同样比较高，居群水平的多态性位点比率为55.11%，预期杂合度为0.1948，Shannon多样性指数为0.2918。AMOVA分析结果与POPGENE计算出的基因分化系数(GST = 0.3505)基本一致，居群间和居群内的遗传变异分别占总遗传变异的32.49%和67.02%。山莨菪的居群间的遗传分化高于其他多种异交植物的均值，但是比同区域分布的几种濒危植物低。本研究结果表明，不同于其他的濒危物种，山莨菪存在较高的遗传多样性，这可能与其独特的繁育系统、种群变化历史和人类活动有关，而人类对其生境的破坏和过度采挖是该种群体减少和濒危的主要原因。UPGMA聚类分析显示，青藏高原东部边缘的3个居群形成独立的一支，而另7个居群聚为另外一支，表明其来源自不同的谱系。我们推测山莨菪居群至少在第四纪末次最大冰期(LGM)存在不同避难所，即青藏高原台面和东部边缘，而间冰期回迁和遗传漂变等因素共同作用形成了目前特定的遗传结构。由于山莨菪具有较大的居群间分化和高的居群内遗传多样性，其保护策略需要采用综合措施，如尽可能多使用原位保护和迁地保护相结合。
其他摘要	Anisodus tanguticus (Maxinowicz) Pascher (Solanaceae), a perennial distributed in the Qinghai-Tibetan Plateau (QTP) and adjacent region, is an endemic species to China. It is an important medicinal plant with high levels of two tropane alkaloids, hyoscyamine and scopolamine, and was listed as Grade Ⅱ National Protected Rare and Endangered plant in 1990. In order to well utilize its medical value sustainably and protect this germplasm resource, we performed RAPD analysis to screen ten populations comprised the interior and edge of QTP. Based on this genetics marker, we intend to explain how the human action affected the genetic diversity of this plant, and further to trace the causes of its current genetic structure. Random ampliﬁed polymorphic DNA markers (RAPD) was assessed to find the genetic diversity and genetic differentiation of A. tanguticus. Finally, we screened 181 individuals from 10 populations by employing 12 random primers, and a total of 92 amplified bands were recorded, 76 of which (PPB = 82.61%) were polymorphic. We also calculated values of expected heterozygosity and Shannon’s information index at the species level of 0.3015 and 0.4459 by using POPGENE program, respectively, and both of these suggested a remarkably high rate of genetic variation at the species level. The average within-population diversity also appeared to be high, with the percentage of polymorphic loci, expected heterozygosity and Shannon’s information index at the population level values of 55.11%, 0.1948 and 0.2918, respectively. Analyses of molecular variance (AMOVA) showed that among- and between-population genetic variation accounted for 32.98% and 67.02% of the total genetic variation, respectively. In addition, Nei’s coefficient of differentiation (GST) was found to be high (0.3505), confirming the relatively high level of genetic differentiation among the populations. These differentiation coefficients are higher than mean corresponding coefficients for outbreeding species, but considerable lower than reported coefficients for some rare species from this region. For A. tanguticus, such genetic scenario could been caused by its breeding pattern, biogeographic history and human impact (because of its medicinal value). The major factors for A. tanguticus which put it into severe danger should be its habitat fragment which casued by human over-collection. The UPGMA dendrogram suggests that three populations from the eastern QTP comprised a distinct group, while the remaining seven, including those located on the western and northern platforms, clustered as another clade. Such genetic scenario could be contributed by the Quaternary climate oscillations, and A. tanguticus may survive at these two different locations, i.e. the QTP eastern edge and western platform. While during the glacial periods (at least the last glacial maximum, or LGM), the individuals re-colonized the current distribution along different routines from these two refugia regions. Both of physical factors and genetic drift may have contributed to current genetic structure. Because of its high among-population genetic differentiation, comprehensive measures on the protection of A. tanguticus should be proposed. As many populations as possible should be considered in any planned in situ or ex situ conservation programs for this species.
页数	59
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3222
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	郑伟. 山莨菪的保护遗传学研究[D]. 西北高原生物研究所. 中国科学院西北高原生物研究所,2009.

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
10001_20061801221501（1199KB）			开放获取	--	请求全文