大理茶和云南大叶茶群体遗传结构的谱系地理学研究

	大理茶和云南大叶茶群体遗传结构的谱系地理学研究
其他题名	A Phylogeography Study on Population Genetic Structure of Camellia taliensis in Comparison with C. sinensis var. assamica
	刘阳
导师	高立志
学位专业	植物学
关键词	大理茶大叶茶谱系地理学遗传多样性群体遗传结构
摘要	作为世界范围内的一种重要饮料作物，茶树（Camellia sinensis）在中国已有至少2000年的栽培历史。云南是茶树种质资源的遗传多样性中心之一，茶组（Sect. Thea）植物中的大部分种在该地区都有分布。本研究利用叶绿体片段trnL-rpl32和核基因片段PAL exon 2的序列数据，检测了云南栽培大叶茶（C. sinensis var. assamica）及其野生近缘种大理茶（C. taliensis）DNA水平上的遗传多样性和群体遗传结构，讨论了大理茶居群的可能进化历史。通过大理茶和大叶茶单倍型之间关系的比较，粗浅地探讨了栽培大叶茶的可能驯化历史。主要研究结果如下： 1. 遗传多样性和群体遗传结构利用叶绿体片段trnL-rpl32对35个居群（大理茶居群24个，大叶茶居群8个，杂交居群3个）的315个个体进行了分析，共得到19个叶绿体单倍型。大理茶的单倍型多态性水平（Hd = 0.83556）高于大叶茶（Hd = 0.67978）。AMOVA分析结果显示大理茶的遗传变异主要存在于居群间（92.54%）；而大叶茶中，分布在居群内（42.90%）的遗传变异接近于存在于居群间（57.10%）的遗传变异。利用核基因片段PAL exon 2对35个居群的516条序列进行了分析，共得到27个核基因单倍型。大理茶的单倍型多态性水平（Hd = 0.83400）远高于大叶茶（Hd = 0.31600）。AMOVA分析结果显示大理茶和大叶茶的核基因片段PAL exon 2的核苷酸变异都主要存在于居群内，分别为73.75% 和81.18%。但大理茶居群间的遗传变异（26.25%）高于大叶茶居群间的遗传变异（18.72%）。 2. 野生大理茶居群的谱系地理学分析利用叶绿体片段trnL-rpl32片段对21个野生大理茶居群进行分析，得到12个叶绿体单倍型。居群间表现出强烈的遗传分化（NST = 0.989，GST = 0.988）。古老单倍型A分布于澜沧江流域的7个居群中。对284条核基因进行分析，得到17个单倍型，其中广布单倍型既存在于谱系内部节点也存在于谱系外部节点。为了检验大理茶是否经历过扩张，我们对叶绿体片段和核基因片段分别进行了分离位点间的失配分析，得到的失配分析曲线都表现为明显的双峰，表明大理茶没有发生近期的群体扩张。推测青藏高原隆升形成的高大山脉加剧了东西方向上大理茶居群间的隔离和分化。在南北方向上，河流（特别是澜沧江）则为大理茶居群的传播和扩散提供了天然通道。 3. 对栽培大叶茶的起源驯化问题的启示通过对单倍型网络图分析，发现3个叶绿体单倍型为大理茶和大叶茶所共有。其中，共有单倍型Hap 4位于网络图的中心，为广布单倍型，推测可能为大理茶和大叶茶分化时不完全的谱系分选所造成。核基因单倍型网络图可以明显地分为大理茶和大叶茶两个分支，表明大理茶可能并非栽培大叶茶的祖先种。对大理茶和大叶茶杂交群体的DNA测序结果进一步证实了大理茶和大叶茶之间存在自然杂交，表明二者之间存在着基因交流。; Tea tree（Camellia sinensis）has been cultivated in China for more than 2000 years. It is one of the most important beverages in the world. Yunnan province is one of the centers of genetic diversity of tea trees. It hosts most species of Sect. Thea of Genus Camellia. Based on sequence data from PAL exon 2 nuclear locus and trnL-rpl32 chloroplast fragments, in this study levels of the genetic diversity and genetic structure of C. sinensis var. assamica and C. taliensis populations were investigated. The phylogeographic history of C. taliensis was traced by using 21 wild C. taliensis populations. Finally, in this study the possible domestication history of C. sinensis var. assamica by comparing the evolutionary relationship between haplotypes of C. sinensis var. assamica and C. taliensis was discussed. The main findings were summarized as follows: 1. Genetic diversity and population genetic structure A total of 315 cpDNA sequences from 35 populations（24 populations of C. taliensis, eight populations of C.sinensis var. assamica and their three hybrid populations）were obtained. In total, 19 haplotypes were identified based on nucleotide variation. The level of haplotype diversity detected in C. taliensis（Hd = 0.83556）was higher than that of C.sinensis var. assamica（Hd = 0.67978）. AMOVA analysis revealed that 92.54% chloroplast variation in C. taliensis was resided among populations. In C. sinensis var. assamica, the proportion resided within populations（42.90%）was slightly lower than but close to that among populations（57.10%）. A total of 516 nDNA sequences from 35 populations were obtained. Of them, 27 disticnct haplotypes were found. The level of haplotype diversity detected in C. taliensis（Hd = 0.83400）was higher than that of C. sinensis var. assamica（Hd = 0.31600）. AMOVA analysis showed that abundant nucleotide variation was found in within populations for both C. sinensis var. assamica（81.18%）and C. taliensis（73.75%）. However, the portion of DNA variation resided among populations of C. taliensis （26.25%）was higher than that of C. sinensis var. assamica（18.72%）populations. 2. Phylogeography of C. taliensis Data from 21 wild populations of C. taliensis were collected for both PAL exon 2 and trnL-rpl32. A total of 12 cpDNA haplotypes were found. Based on the cpDNA halotypes, a high genetic differentiation was detected among the sampled populations（NST = 0.989, GST = 0.988）. The ancient haplotype A was found in seven populations inhabiting the Lancang River regions. In addition, 17 nDNA haplotypes were totally found. The haplotypes with a widespread distribution represented both internal and tip nodes of the gene tree. The lack of population expansion was supported by the multimodal mismatch distribution at PAL exon 2 locus and trnL-rpl32 gene fragments. The results indicate that surface uplift of eastern Tibet formed large-scale drainage pattern which intensified the genetic differentiation among populations of C. taliensis. However, the rivers (e.g. Lancang River) provided northwards or southwards natural corridors for the dispersal and distribution of C. taliensis. 3. Implications for the origin and domestication of cultivated C. sinensis var. assamica By analyzing haplotypes which were shared by C. sinensis var. assamica and C. taliensis, we found that haplotype Hap 4 with a widespread distribution represented the center note of the cpDNA haplotype network. Such an observation came from incomplete lineage sorting. The nDNA haplotype network was distinctly divided into two clades, the clade of C. taliensis and the clade of C. sinensis var. assamica. The results clearly suggest that the species C. taliensis was not the wild progenitor of cultivated C. sinensis var. assamica. The hybrid individuals between C. sinensis var. assamica and C. taliensis were confirmed by the DNA sequences, showing that strong gene flow might occurr between C.sinensis var. assamica and C. taliensis.
语种	chi
	2009-05-21
学位授予单位	中国科学院昆明植物研究所
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/442
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	刘阳. 大理茶和云南大叶茶群体遗传结构的谱系地理学研究[D]. 昆明植物研究所. 中国科学院昆明植物研究所,2009.

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