title: Molecular Diversity and Population Structure of a Worldwide Collection of Cultivated Tetraploid Alfalfa (Medicago sativa subsp. sativa L.) Germplasm as Revealed by Microsatellite Markers.
abstract: Information on genetic diversity and population structure of a tetraploid alfalfa collection might be valuable in effective use of the genetic resources. A set of 336 worldwide genotypes of tetraploid alfalfa (Medicago sativa subsp. sativa L.) was genotyped using 85 genome-wide distributed SSR markers to reveal the genetic diversity and population structure in the alfalfa. Genetic diversity analysis identified a total of 1056 alleles across 85 marker loci. The average expected heterozygosity and polymorphism information content values were 0.677 and 0.638, respectively, showing high levels of genetic diversity in the cultivated tetraploid alfalfa germplasm. Comparison of genetic characteristics across chromosomes indicated regions of chromosomes 2 and 3 had the highest genetic diversity. A higher genetic diversity was detected in alfalfa landraces than that of wild materials and cultivars. Two populations were identified by the model-based population structure, principal coordinate and neighbor-joining analyses, corresponding to China and other parts of the world. However, lack of strictly correlation between clustering and geographic origins suggested extensive germplasm exchanges of alfalfa germplasm across diverse geographic regions. The quantitative analysis of the genetic diversity and population structure in this study could be useful for genetic and genomic analysis and utilization of the genetic variation in alfalfa breeding.
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100193, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Qiang
authors.affiliation: National Animal Husbandry Service, Ministry of Agriculture, Beijing 100125, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100193, China.
authors.forename: Zhengli
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100193, China.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100193, China.
authors.forename: Hongwen
authors.initials: H
authors.lastname: Gao
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100193, China.
authors.forename: Zan
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000483:Alleles; D032461:Chromosomes, Plant / Q000235:genetics; D016000:Cluster Analysis; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D000455:Medicago sativa / Q000235:genetics* / Q000254:growth & development*; D018895:Microsatellite Repeats / Q000235:genetics*; D010802:Phylogeny; D025341:Principal Component Analysis; D012639:Seeds / Q000235:genetics*; D057891:Tetraploidy