苜蓿地方品种遗传多样性的研究—RAPD标记

利用ＲＡＰＤ技术对中国１８个苜蓿品种和北美９个苜蓿基本种质来源的代表品种各取１０个单株进行多态性分析。结果表明，苜蓿品种内和品种间均具有明显的多态性，如采用混合样分析则掩盖了品种内的多态性，而品种间的多态性则明显降低。７条引物共检测了５２个位点，其中５０个位点是多态的。品种间差异是由该５０个多态位点出现带谱的频率不同而体现的。

Study on the Genetic Diversity of the Alfalfa Local Varieties (Medicago sativa L. ) based on RAPD markers

Genetic diversity of the 18 alfalfa local varieties in China and the 9 alfalfa varieties representing the 9 alfalfa basic germplasm sources in North America were studied using RAPD markers.Resultsshowed that: Obvious polymorphisms within and among varieties can be revealed by amplifying individula DNA samples. Meanwhile, polymorphisms within varieties are concealed, and among varieties are obviously reduced,when using bulk samples.7 primers reveal total of 52 loci,and all the loci are scored as 1 forpresent and 0 for absent. Among the 52 loci,50 are polymorphic. Defference between varieties is reflected by the different frequencies on different loci. Total genetic diversity (HT) of the 18 alfalfa local varieties in China are close to, and polymorphic loci rate (P) and genetic diversity within varieties(HS)are higher than,that of the 9 alfalfa varieties in North America, indicating that the varieties in China are more heterozygous, and genetic variation within varieties are relatively larger. Analysis of gene differential coefficient (GST) indicating that genetic variation of Medicago sativa is mainly exits within varieties . This characteristic is related to the breeding system (out - breeing) of Medicago sativa.GST of the 18 alfalfa local varieties in China is smaller than that of the 9 alfalfa varieties in North America, indicating that more genecommunications occurred between the alfalfa local varieties in China, and variation within varieties takes up more of the total genetic variation. These results verify that the genetic structure of ch alfalfavarieties isalso related to their geographic distribution and sources. Polymorphisms revealed by RAPD markers arehigher than that of seed storage protein markers , indicating that polymorphism vary with different t levels of gene expression.