title: Cloning and characterization of chromosomal markers in alfalfa (Medicago sativa L.).
abstract: Eleven tandemly repetitive sequences were identified from a Cot-1 library by FISH and sequence analysis of alfalfa (Medicago sativa). Five repetitive sequences (MsCR-1, MsCR-2, MsCR-3, MsCR-4, and MsCR-5) were centromeric or pericentromeric, of which three were satellite DNAs and two were minisatellite DNAs. Monomers of 144, 148, and 168 bp were identified in MsCR-1, MsCR-2, and MsCR-3, respectively, while 15 and 39 bp monomers were identified in MsCR-4 and MsCR-5, respectively. Three repetitive sequences were characterized as subtelomeric; one repetitive sequence, MsTR-1, had a 184 bp monomer, and two repetitive sequences had fragments of 204 and 327 bp. Sequence analysis revealed homology (70-80 %) between MsTR-1 and a highly repeated sequence (C300) isolated from M. ssp. caerulea. Three identified repetitive sequences produced hybridization signals at multiple sites in a few of the chromosomes; one repetitive sequence was identified as the E180 satellite DNA previously isolated from M. sativa, while the other 163 and 227 bp fragments had distinct sequences. Physical mapping of the repetitive sequences with double-target FISH revealed different patterns. Thus, nine novel tandemly repetitive sequences that can be adopted as distinct chromosome markers in alfalfa were identified in this study. Furthermore, the chromosome distribution of each sequence was well described. Though significant chromosome variations were detected within and between cultivars, a molecular karyotype of alfalfa was suggested with the chromosome markers we identified. Therefore, these novel chromosome markers will still be a powerful tool for genome composition analysis, phylogenetic studies, and breeding applications.
authors: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining 810001, China.
authors: Feng
authors: F
authors: Yu
authors: Yunting
authors: Y
authors: Lei
authors: Yuan
authors: Y
authors: Li
authors: Quanwen
authors: Q
authors: Dou
authors: Haiqing
authors: H
authors: Wang
authors: Zhiguo
authors: Z
authors: Chen
mesh_terms: D032461:Chromosomes, Plant; D003001:Cloning, Molecular; D004276:DNA, Satellite; D015723:Gene Library; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D000455:Medicago sativa / Q000235:genetics*; D020161:Physical Chromosome Mapping; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences
chemical_list: D004276:DNA, Satellite
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