新疆核桃4个栽培品种及野生种的遗传多样性分析

以新疆地区种植的4个核桃(Juglans regia Linn.)栽培品种(包括新栽培品种'温185'和'新新2'以及老栽培品种'新丰'和'扎343')及巩留野核桃自然保护区生长的野生核桃为研究对象,对其cpDNA的psbK-psbI区间和mtDNA的COX2 intronⅠ区间以及nrDNA的ITS和ETS区间的DNA片段序列进行了比较分析,并对其MP、ML和UPGMA系统发育树进行了分析;此外,还基于SSR分子标记结果对其进行了遗传多样性指数、UPGMA系统发育树和遗传分组分析.结果表明:野生种与4个栽培品种的cpDNA和mtDNA片段序列无碱基变异,而其nrDNA的片段序列却存在3个碱基变异,但4个栽培品种间无碱基变异.以麻核桃(J.hopeiensis Hu)为外类群,基于上述4个DNA片段序列构建的MP、ML和UPGMA系统发育树的聚类结果一致,均表现为4个栽培品种聚为一组,而野生种和麻核桃则分别单独聚为一组.野生种的观测杂合度、预期杂合度和固定指数分别为0.383、0.448和0.153,4个栽培品种的上述3个遗传多样性指数分别为0.428~0.576、0.423~0.619和-0.043~0.234.基于SSR分子标记结果的UPGMA系统发育树和分组数为5的遗传分组结果均表明:野生种和品种'温185'分别单独为一组;品种'新新2'和'新丰'为一组;而品种'扎343'也单独为一组,但与品种'新新2'和'新丰'遗传关系较近.遗传分组结果还表明:分组数为3更利于明确品种'扎343'的分组地位,此时,其与品种'新新2'和'新丰'为一组.综合分析结果表明:核桃4个栽培品种间的遗传差异较小,且老栽培品种的遗传多样性总体上高于新栽培品种;野生种与栽培品种间具有明显的遗传差异,说明在育种或栽培过程中核桃种质资源的遗传多样性可能会逐渐降低,并且,该野生种可为核桃的分子育种提供天然的基因库资源.

Analysis on genetic diversity of four cultivars and wild species of Juglans regia in Xinjiang

Taking four cultivars ( including newly cultivar of 'Wen185' and 'Xinxin2' and old cultivar of 'Xinfeng' and'Za343' ) of Juglans regia Linn. planted in Xinjiang region and wild J. regia grown in Gongliu Wild Walnut Nature Reserve as research objects, the DNA fragment sequences of psbK-psbI interval of cpDNA and COX2 intron Ⅰ interval of mtDNA, and ITS and ETS intervals of nrDNA were comparatively analyzed, and their MP, ML and UPGMA phylogenetic trees were analyzed. Otherwise, based on SSR molecular marker results, their genetic diversity indexes, UPGMA phylogenetic tree and genetic cluster were also analyzed. The results show that there is no base variation of fragment sequences of cpDNA and mtDNA among wild species and four cultivars, while there are three base variations of fragment sequences of their nrDNA, but there is no base variation among four cultivars. Taking J. hopeiensis Hu as an outer group, the cluster results of MP, ML and UPGMA phylogenetic trees constructed based on above four DNA fragment sequences are identical, all appear that four cultivars are clustered into one group, while wild species and J. hopeiensis are clustered into independent group, respectively. The observed heterozygosity, expected heterozygosity and fixation index of wild species are 0. 383, 0. 448 and 0. 153, respectively, and the above three genetic diversity indexes of four cultivars are 0. 428-0. 576, 0. 423-0. 619 and-0. 043-0. 234, respectively. The results of UPGMA phylogenetic tree based on SSR molecular marker results and genetic cluster with cluster number of 5 both show that wild species and cultivar 'Wen185 ' are independent group, respectively, and cultivar 'Xinxin2 ' and'Xinfeng' are one group, while cultivar 'Za343 ' is also an independent group, but it has a closer genetic relationship with cultivar 'Xinxin2 ' and 'Xinfeng ' . The genetic cluster results also show that cluster number of 3 is more suitable for defining the cluster status of cultivar 'Za343' , right now, it is one group with cultivar'Xinxin2' and'Xinfeng' . The result of comprehensive analysis indicates that the genetic difference among four cultivars of J. regia is small, and in general, the genetic diversity of old cultivars is higher than that of newly cultivars. In addition, there are obvious genetic differences between wild species and cultivars, meaning that genetic diversity of germplasm resource of J. regia might decrease gradually during breeding or cultivation processes, and the wild species can provide natural gene pool resource for molecular breeding of J. regia.