欧洲与东亚小麦品种遗传多样性的比较分析

 【目的】在分子水平上回答欧洲和东亚小麦品种的遗传关系和多样性差异；同时对Genomic-SSR（gSSR）和EST-SSR（eSSR）多态性水平进行比较分析。【方法】利用38个Genomic-SSR引物对和44对EST-SSR引物对分析371份欧洲小麦品种和363份东亚品种。【结果】共检测到865个等位变异，每个引物对的等位变异数为1～50，平均为10.42；多态性信息含量（PIC）为0～0.91, 平均为 0.53；欧洲和东亚品种分别检测到730、716个等位变异，特有等位变异分别为150、135，平均遗传丰富度分别为8.80和8.61，遗传多样性指数分别为 0.46 和0.52。欧洲和东亚小麦品种在聚类图上明显地划分为两大类群；每个国家或大区聚类结果与其地理分布基本一致，即相邻国家或地区的品种亲缘关系更近一些。近一半基因座的等位变异频率及其分布在欧洲与东亚材料间存在明显差异。 通过标记/性状关联分析，在4B、5A、6A、7B染色体上发现6个影响穗粒数、千粒重、株高、抽穗期、有效分蘖等重要农艺性状的基因座，其中个别基因座优势等位变异差异可能与东亚、欧洲品种的分化密切相关。中国20世纪50～80年代育成品种在大的聚类上明显靠近欧洲材料、而远离中国50年代以前的育成品种和地方品种，这与中国的育种实际相吻合。基于Genomic-SSR和基于EST-SSR的聚类图整体趋势是一致的，但由前者估算的遗传距离远高于后者，因此，一般的SSR较功能基因SSR更易发生变异，由育种选择所引起的分化更快。【结论】在中国今后的小麦育种中，需要通过杂交、回交，对欧洲品种的一些重要基因座等位变异（基因）进行置换，方有可能实现“洋为中用”的目的。

Comparison of Genetic Diversity Level between European and East-Asian Wheat Collections Using SSR Markers

Bread wheat (Triticum aestivum L.) is a major cereal crop for both human and animal food. This species is originating from the Fertile Crescent in the Middle-East. At the Neolithic period, initial germplasm was widespread by the first farmers in both Europe and East-Asia. Therefore, wheat diversity evolved under different environmental conditions and selection pressures in each continent. Today, the comparison of genetic diversity level between these two contrasted wheat germplasms may be a useful way, for both geneticists and breeders, to find new sources of variation. In this paper, 371 European and 363 Asian collections were genotyped by 38 genomic SSR and 44 EST-SSR markers. Total 865 alleles were detected, with range from 1 to 50 and a mean of 10.42. Polymorphism information content (PIC) ranged from 0 to 0.91 with an average of 0.53. Genetic diversity level in East-Asia was higher than that in Europe. European and Asian accessions were divided into two distinct sub-groups by PCO based on 83 SSR loci. The position of materials in the dendrogram was accordant with their geographical location, i.e. accessions from near geographical location were jointing into neighbours. Allele differentiation between the two continents at some loci such as Xgwm186, Xgwm257, Gpwm7433 and Gpwm7443 was very significant. This may be corresponding to the natural and breeding selection, which was supported by the marker/trait association analysis results. Chinese varieties released from 1950 to 1980 were clustered into one big group with Europeans, and far away from native landraces and varieties released before 1950. This is consistent with wheat breeding history of China. Diversity revealed by genomic SSRs was much higher than that by EST-SSRs. However, the cluster trend based on the two types of SSR was consistent. Therefore, differentiation of repetitive DNA was much rapider than functional genes in breeding selection. European germplasms can be efficiently used in Chinese wheat breeding program through backcross breeding method.