唐古特大黄遗传多样性研究

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	唐古特大黄遗传多样性研究
	胡延萍
学位类型	博士
导师	张怀刚 ; 李毅
	2010-05-21
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位专业	生态学
关键词	唐古特大黄核型 b 染色体遗传多样性 Issr
摘要	大黄是我国著名的传统中药材，具有泻热通肠，凉血解毒，逐瘀通经之功效。唐古特大黄（Rheum tanguticum Maxim. ex Balf.）是我国特有物种，为中国药典记载的正品大黄之一。青海省是其道地药材的主产区，随着临床应用的日益广泛，掠夺式的滥采已导致大量野生资源的锐减。迄今为止，唐古特大黄的研究主要集中于化学成分分析和临床应用等方面，迫切需要对其野生居群的遗传多样性进行研究，为合理利用、引种驯化和野生资源保护提供理论依据。本研究从细胞生物学和分子生物学两方面对野生及栽培居群遗传多样性进行分析和比较研究，主要结果如下： 1 核型分析通过对唐古特大黄17 个居群的核型分析发现，不同居群的核型类型均为较原始的1A 型，核型公式为K=2n=22=2sm+20m 或K=2n=22=22m。在ZQ, XGM,MX, NX wild 和XM 五居群内出现高频率的B 染色体，且B 染色体的数目为1、2、3、4、6、7 不等。染色体相对长度和臂比值的巢式方差分析表明，平均32.90%的遗传变异来自于居群间，而大部分遗传变异（67.10%）来自于居群内的个体和细胞间。 2 ISSR 分子标记研究（1）在DNA 分子水平上，唐古特大黄野生居群与栽培居群均具有较高遗传多样性，但野生居群遗传多样性略高于栽培居群。唐古特大黄野生居群具有较高遗传多样性（PPB = 93.87%，He = 0.2703，I = 0.4186），遗传分化系数Gst 为0.3702；唐古特大黄栽培居群也具有较高遗传多样性（PPB = 85.14%，He = 0.2478，I =0.3280），而遗传分化系数Gst 为0.2893。在物种水平上，唐古特大黄多态位点百分率为95.09%，Nei 基因多样性He = 0.2683，Shannon 多样性指数I = 0.4160，遗传分化系数Gst = 0.3609，表明唐古特大黄遗传多样性总体上仍处于较高水平。（2）唐古特大黄野生居群AMOVA 分析的Фst = 0.2932，表明29.32%的遗传变异存在于居群之间，70.68%的变异存在于居群内。（3）唐古特大黄野生居群遗传距离与地理距离的Mantel 检验表明，r = 0.4813，P = 0.005，二者具有较强的正相关。（4）遗传多样性与生态因子的Pearson 相关性分析表明，唐古特大黄的遗传多样性与海拔呈极显著的正相关（P＜0.01），与经纬度和年平均气温均呈显著的负相关（P＜0.05）；唐古特大黄遗传多样性与年平均降水量呈正相关，但相关性不显著（P＞0.05）。揭示了海拔、温度和水分可能是影响唐古特大黄遗传多样性的重要外部因素。 3 综合两种标记的结果：唐古特大黄具有丰富的遗传多样性，且居群内遗传多样性高于居群间遗传多样性，表明居群内遗传变异是唐古特大黄变异的主要来源。 4 不同水平的标记方法，得出的遗传多样性结果不完全一致，表明在进行遗传多样性研究时，应综合运用多种方法，全面客观地评价物种遗传多样性。
其他摘要	Rhubarb, a well-known traditional Chinese herb, has been widely used as a purgative, anti-inflammatory and detoxicated agent, as well as elimating stasis. Rheum tanguticum Maxim. ex Balf., a species endangered and endemic to China, is recognized and recorded in the Chinese Pharmacopoeia as one of official rhubarb. Qinghai Province is the major producing area of genuine R.tanguticum. Recently, the increasing clinical application of R. tanguticum products have led to overexploitation. As a result, natural resources have decreased remarkably. Now, most studies on R. tanguticum is about the chemical composition and clinical practices, therefore, the exploration and evaluation of genetic diversity in wild populations of R. tanguticum is imperative to provide fundamental information for its sustainable use, domestication and efficient conservation. In this study, the genetic diversity of wild and cultivated populations was surveyed at cytology and molecular biology level. The main results are as follows: 1 The karyotypic analysis of 17 populations of R. tanguticum indicated that the karyotypes of all populations were original “1A” type. The karyotype formula were K=2n=22=2sm+20m or K=2n=22=22m. High percentage of B chromosomes was observed in some populations such as ZQ, XGM, MX, NX wild and XM, and the number was 1, 2, 3, 4, 6 and 7. The nested analysis of variance of relative length and arm ratio indicated that about 32.90% genetic variation was attributed to the differentiation among populations and the remaining 67.10% within population. 2 The genetic diversity of 238 individuals from 20 populations of R. tanguticum in Qinghai Province was investigated using inter-simple sequence repeats (ISSR) markers. The results showed that: (1) Both the wild and cultivated populations of R. tanguticum maintain a relatively high level of genetic diversity. The genetic diversity was found higher in wild populations (PPB = 93.87%, He = 0.2703 and I = 0.4186) than that in cultivated ones (PPB = 85.14%, He = 0.2478 and I = 0.3280). Additionally, there was more genetic differentiation among wild populations (Gst = 0.3702) than cultivated populations (Gst = 0.2893). At the species level, R. tanguticum displayed a relatively high genetic diversity with PPB = 95.09%，He = 0.2683，I = 0.4160, and the major genetic variation resided within populations (63.91%). (2) AMOVA analysis of wild populations indicated that the genetic variation was mainly found within populations (70.68%), and only 29.32% of variance was among populations. (3) Mantel test revealed a significant correlation between genetic and geographic distances in wild populations (r = 0.4813, P = 0.005). (4) The Pearson correlation analysis of genetic diversity and ecological factors demonstrated that the genetic diversity of R. tanguticum wild populations positively correlated with altitude and annual mean precipitation, but negatively correlated with longitude, latitude and annual mean temperature. This implied that altitude, temperature and precipitation might be important ecological factors that impact the genetic diversity of R. tanguticum. 3 From our investigation with these two methods, we conclude that there is a large amount of genetic diversity in R. tanguticum. The variation within populations, which is significantly higher than that between populations, was the main causes that result in variation of R. tanguticum.4 The genetic diversity was not the same with different methods, and various investigative approaches should be applied to objectively estimate the genetic diversity of species.
学科领域	生物科学
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3398
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	胡延萍. 唐古特大黄遗传多样性研究[D]. 北京. 中国科学院研究生院,2010.

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