应用SSR分子标记分析国外种质对我国小麦品种的遗传贡献

利用363对SSR标记分析了在我国小麦生产和育种中发挥了重要作用的11份国外引进品种和33份选育品种的遗传组成，旨在揭示国外种质对我国小麦品种改良的遗传贡献，指导种质资源引进和利用。国外种质包含了选育品种所发现等位变异的76.3%。与不同时期小麦品种等位基因多样性比较发现，国外种质的平均等位变异数最多(3.92)，20世纪60年代(2.86)和70年代(3.01)基本一致，80年代有所升高(3.46)。品种间遗传距离比较与品种等位基因多样性结果相吻合。比较引进和选育品种在SSR位点的等位变异频率变化，发现至少在33个SSR位点，国外种质等位变异在我国小麦育种中被优先选择(该等位变异在引进和选育品种的分布频率均高于70%)，其中一些位点已知与产量、生育期和抗病等性状密切相关。表明引进品种在以上基因组区域对我国小麦品种具有非常高的遗传贡献。

Genetic Contribution of Introduced Varieties to Wheat Breeding in China Evaluated Using SSR Markers

Foreign germplasm has exerted important influence on wheat (Triticum aestivum L.) breeding in China. To uncover the genetic contribution of introduced varieties to Chinese wheat breeding, 44 representative accessions, consisting of 11 introduced important parents from 1950s to 1970s and 33 representative domestic varieties which were released in different years in China, were evaluated using 363 SSR markers distributing on 21 chromosomes. The 11 introduced accessions contained 76.3% of the alleles presented in total 33 Chinese accessions. Comparing the pattern of variability among introduced accessions and the groups of varieties released over time, we found that the mean number of alleles amplified was the highest in foreign germplasm (3.92), similar to each other between 1960s and 1970s (2.86 and 3.01, respectively), and that in 1980s was a little higher (3.46). The result on genetic distance among different groups was accorded with the pattern of the allelic diversity. On the other hand, comparing the allelic frequencies between introduced and improved accessions at each SSR locus we found that certain chromosomal regions underwent strong selection in wheat breeding. At least 33 SSR loci on 14 chromosomes with the exception of 4A, 6A, 7A, 1B, 3B, 3D, and 5D, the alleles amplified in foreign accessions were selected preferentially and transmitted to Chinese accessions, whose frequencies were over 70% in either group of accessions. Furthermore, some of the markers were correlated with known wheat genes controlling important traits reported in literatures, including resistance to pests such as strip rust, leaf rust and powdery mildew, and other characters such as yield, growth stage and dormancy. In conclusion, the chromosomal regions selected preferentially play an important role in the improvement of wheat in China, which should be studied further.