中国野生核桃遗传多样性及栽培核桃起源研究

The genetic variation of germplasm resources is the basis for the origin of the modern cultivars. Natural and human selections were important forces driving the evolution of species, especially crops. This project will determine the genetic diversity of the germplasm of the economically important tree species Juglans regia. We will use field investigation methods, molecular biology, and molecular evolutionary methods to study the variation in genetic diversity between natural walnut populations and walnut cultivars. We will examine variation in walnut genomic DNA at two chloroplasts markers, one Internal transcribed spacers(ITS) marker, and eight to ten microsatellite markers. We will determine the genetic diversity and genetic structure of natural populations and cultivated germplasm by comparisons within and among populations sampled across the range of the species in China. Using analytical methods based on theories of molecular evolution, we will determine relatedness among individuals and populations, the origins and evolutionary history of walnut cultivars. We will use the molecular phylogeography together with population-level data identify evolutionary history for walnut, which are typically sources of useful genetic variation. The results will advance our understanding of walnut germplasm resources and the spatial distribution of walnut genetic diversity, and the evolutionary relationship between natural walnut trees and walnut cultivars. It will provide basic data for understanding the bio-geography of Juglans and for predicting the response of the genus to climate change. These results will guide the development and conservation of walnuts germplasm resources for geneticc breeding and molecular evolution.

种质资源遗传多样性的研究可以追溯现代植物种群的起源及其进化历史。自然选择和人工选择是影响物种进化过程的两个关键因素。本项目拟以我国重要经济资源树种核桃（Juglans regia）为主要研究对象，利用野外调查和分子生物学等方法研究核桃自然和人工栽培群体在两套单亲遗传叶绿体DNA序列、双亲遗传核基因ITS序列以及微卫星(SSR)分子标记序列上的遗传变异式样，确定野生和栽培种群间、种群内和整个地理分布范围上的遗传多样性和遗传结构，对野生核桃种质资源进行遗传分析评价；利用系统进化方法揭示广泛栽培核桃与野生核桃之间的亲缘进化关系；利用谱系地理学方法，构建该物种谱系进化历史。研究结果有助于深刻认识我国野生核桃种质资源的遗传多样性、野生与栽培核桃之间的进化关系，以及该属植物响应气候变迁的生物地理学模式，也对核桃基因资源的开发利用和保护提供科学依据。

物种种质资源遗传多样性的研究可追述现代植物种群的起源。自然和人工选择在物种进化过程中发挥着很重要的作用。本项目拟以我国重要经济资源树种核桃为研究对象，利用野外调查、分子生物学等方法研究核桃自然和人工栽培群体在三套单亲遗传叶绿体（trnT-trnF、matK和rbcL）DNA序列以及10对核基因微卫星(SSR)上的遗传变异式样，确定野生和栽培种群间、种群内和整个地理分布范围上的遗传多样性和遗传结构，对野生核桃种质资源进行遗传分析评价；利用分子进化方法阐明广泛栽培核桃与野生核桃之间的亲缘关系和进化起源；利用溯祖理论等方法对群体遗传学数据进行计算和模拟，构建该物种谱系进化历史，从分子水平验证我国核桃冰期避难所和冰期后迁移/扩散路线。研究结果对理解核桃遗传多样性，野生与栽培核桃之间的进化关系，核桃植物响应气候变迁的生物地理学模式将提供典型依据，也对核桃基因资源的开发利用和保护，育种和进化研究提供借鉴意义。