川榛居群遗传多样性及与近缘种的系统发育关系研究

Corylus kweichowensis Hu is the Chinese unique plant resources, which has high economic and cultivated values. It has good characteristics as a parent material to cultivate new hazel varieties, especially suitable for cultivation in the south of China. C. kweichowensis Hu is mainly in wild state distribution now, which has not been effective developed and utilized. It’s population genetic diversity of group level has not been studied until now. In addition, there is a controversial taxonomic relationship between C. kweichowensis Hu and C. heterophylla Fisch with similar morphological characteristics. In this project, the genetic variation on group level of Corylus will be investigated by using morphological markers, SSR, AFLP molecular markers with nuclear ITS and chloroplast DNA sequences methods. Phylogenetic tree and network diagram will be constructed. Meanwhile，the ancient haplotype and distribution will also be determined. We will analysiz the distribution of original group and phylogenetic relationship of these two germplasm. The comprehensive evaluation data of genetic diversity can be obtained through this project, which can puts forward the feasible strategy of protection for C. kweichowensis Hu. The resluts of this project can also provide some evidence to elucidate the evolutionary relationship between C. kweichowensis Hu and C. heterophylla Fisch.

川榛（Corylus kweichowensis Hu ）是我国特有的榛属植物资源，具有较高的经济价值和育种价值，是培育适合南方栽培的榛子新品种的良好亲本材料。川榛目前呈野生状态分布，没有进行有效的开发利用，其居群水平的遗传多样性尚未有研究。另外，对形态特征较为相近的川榛和平榛之间的分类学关系也存在着争议。针对上述问题，本研究拟利用形态标记、SSR、AFLP分子标记结合核ITS和叶绿体DNA序列，研究川榛居群的遗传变异水平；同时构建系统发育树及网络图，确定古老单倍型及其分布地，分析川榛和平榛的原始类群及系统进化情况。通过研究可以获得川榛资源遗传多样性的综合评价数据，为川榛资源的保护提出可行的策略，同时阐明川榛和平榛的系统进化关系。

榛子是重要的经济树种,其果实是世界四大坚果之一,营养丰富,用途广泛,经济价值高。宝贵的资源是育种的基础，川榛(Corylus kweichowensis Hu)是我国目前最有生产价值和育种潜力的榛种之一。本研究利用SSR分子标记对川榛居群的遗传多样性情况进行了检测，结果表明川榛居群表现出较高的遗传多样性，遗传分化系数（FST）和AMOVA分析均表明川榛居群的遗传变异主要发生在居群内个体间，居群间遗传变异较低。居群间存在较高的基因流。根据居群的遗传多样性情况，提出了优先就地保护的居群；利用1对ITS序列和5对叶绿体DNA序列，对榛属植物进行遗传多样性和系统发育分析，基于核ITS序列获得的网络关系基本符合当前的形态学分类和系统发育关系，基于叶绿体的单倍型分布与地理分区密切相关；利用2b-RAD 测序获得的SNP 位点，解析洲际分离的榛属形态模式和进化史。结果表明榛属和虎榛子属最近共祖时间为53.7Ma，中新世中期至上新世，榛属物种快速分化，分析证明中国西南地区为世界榛属植物最可能的祖先分布区，榛属物种洲际间断分布的过程中，经历了多次迁移与隔离事件。两条重要的长距离迁移路线导致榛属植物从东亚扩散到北美洲和欧洲。本项研究为我国野生川榛资源的保护以及开发利用奠定了基础，相关利用工作已经启动，我们已经选出了多个川榛的优良单株，并开展了杂交育种工作。