中国苜蓿地方品种种子贮藏蛋白标记──遗传多样性的研究

Study on the Genetic Diversity of the Alfalfa Local Varieties (Medicago sativa L.) in China: Seed Storage Protein Markers

利用SDS-PAGE方法对中国18个地方首倩品种和北美9个苜蓿基本种质来源的代表品种，各选对粒种子进行贮藏蛋白分析。结果表明，苜蓿品种内和品种间均具有明显的多态性，但采用混合样分析则掩盖了品种内的多态性。苜蓿种子贮藏蛋白单体分子量在2．17～83．8KD之间。在所检测的25个表现稳定、分辨率高的单株中，有12个为多态。多态单体在不同品种中出现的频率各异。中国18个前信地方品种的平均多态位点比例和品种内基因多样性均高于北美9个苜蓿品种。表明我国首精品种内的变异幅度较大，品种的杂合性较高。基因分化系数（GST）分析结果表明，苜蓿的遗传变异主要存在于品种内，这一特点与其繁育体系（异交）有关。中国18个苜蓿品种的CST不及北美9个苜蓿品种的一半，表明中国地方苜蓿品种间的基因交流较强，遗传变异相对更多地存在于品种内。同时说明苜蓿品种的遗传结构不仅与繁育体系有关，而且与品种的来源及地理分布有直接的关系。

Genetic diversity of the 18 alfalfa local varieties in China and the 9 alfalfa varieties repre-senting the 9 basic alfalfa germplasm sources in North America were studied using seed storage proteinmarkers. Results showed that: Obvious polymorphisms within and among varieties can be revealed usingelectrophoresis of alfalfa single seed samples. Meanwhile, polymorphisms within varieties are concealedwhen using bulk samples. Monomer weights of alfalfa seed storage proteins are 21. 7 ~ 83. 8KD. 25 stableand distinct monomers are scored as 1 for present and 0 for absent, and frequency of each monomer iscalculated based on these data. Among the 25 monomers, 12 are polymorphic. Difference between vari-eties is reflected hy the different frequencies of different monomers. Total gene diversity (HT), polymor-phic loci rate (P)and gene diversity within varieties (Hs) of the 18 alfalfa local varieties in China arehigher than those of the 9 alfalfa varieties in North America. These results indicate that the varieties inChina are mere heterozygous and genetic variation within varieties is relatively larger. Analysis of genedifferential coefficient(GST) indicating that genetic variation of Medicage sativa is mainly exits within va-rieties. This charateristic is related to the breeding system (out-breeding) of Medicage sativa. GST of the18 alfalfa local varieties in China is smaller than that of the 9 alfalfa varieties in North America, indicat-ing that more gene communications occurred between the alfalfa local varieties in China, and variationwithin varieties takes up more of the total genetic variation. These results variety that the geneic structureof alfalfa varieties is also related to their geographic distribution and sources.