Introduced Alfalfa Germplasm Phenotypic Traits And SSR Molecular Markers Research

Alfalfa is one of the most important forages in the world. However, China is relatively lack of alfalfa germplasm and so has a narrow genetic background. Importation of foreign alfalfa materials is a practical way to enrich the genetic pool for alfalfa breeding in China. In order to effectively utilize introduced alfalfa germplasm, this paper, using30 introduced alfalfa material 4 domestic contrast materials, examined their main phenotypic traits and SSR molecular markers. The results are as follows:1. The appraisement of 30 introduced alfalfa in the field, showed that:there are 2 Medicago falcate L.,15 Medicago sativa L. and 13 Medicago varia Martin.; there are 12 upright materials,10 semi-upright materials, and 8 prostrate materials.2. The comprehensive appraisements for 30 introduced materials in the aspects of forage yield, seed yield, tiller length, plant height and wintering survival rate showed: 9 materials had good comprehensive phenotypic characters, the order is 10>2>9>34>28>4>3>16>15. These materials were better than the domestic materials Medicago sativa L.cv. Gongnong No.2. The American-indroduced material No.10, from America, showing a superior performance in term of forage yield, seed yield and winter survival rate, can be considered a priority material for further selection program.3. Correlation analysis for the 34 materials showed that forage yield were primarily determined by plant height and internode length. Apparent seed yield was primarily determined by fertile tiller number and seed number per pod. Potential seed yield was determined by fertile tiller number, inflorescence number per tiller, floret number per inflorescence and ovule number per pod. Actual seed yield was affected by climatic conditions and had low correlations with seed yield components.4. There are 9 SSR primers were used in 373 plants of 34 alfalfa materials and produced 187 fragments including 155 polymorphic loci.The average loci per primer were 20.78. The polymorphic loci percentage of 9 primers in 34 materials was 85.72%, the average genetic diversity was 0.1609 and the average Shannon information index was 0.2494. Genetic differentiation coefficient was 0.2015, showing that the materials had large genetic differentiation.5. Population structure analysis of 30 introduced alfalfa and4 domestic materials found that, when K=7 the likelihood value is maximum, therefore 34 materials can be divided into 8 groups, including 7 specific groups and 1 mixture group. When the Q value is equal to 0.3, there are 29 materials divided into specific groups, the percentage is 85.29%. Introduced materials distributed in the 7 groups, and 4domestic materials only distributed in the two groups.6. The correlation coefficient of SSR molecular marker and the phenotypic trait is 0.0849> 0.01, showing a non-significant correlation.