Genetic linkage map of alfalfa (Medicago sativa) and its use to map seed protein genes as well as genes involved in leaf morphogenesis and symbiotic nitrogen fixation
We have constructed a genetic map for Medicago sativa using morphological, isozyme, seed protein, RFLP and RAPD markers. For this we have crossed two diploid alfalfa plants (the yellow-flowered diploid Medicago sativa ssp. quasifalcata k93 and the purple-flowered Medicago sativa ssp. coerulea w2) which belong to the Medicago sativa complex. One F1 plant (F1/1) was selected and self pollinated to produce the F2 population which consisted of 138 individuals. Mapping was carried out in this segregating population by determining the genotype of more than 1000 genetic markers for the individual plants. The genetic map consists of eight linkage groups corresponding to the eight haploid chromosomes of alfalfa. The genetic length of the genome is approximately 550 cM, consequently the physical equivalent of 1 cM is about 1500 kb in average. The map location of the sticky leaf mutation conditioning altered leaf morphogenesis as well as an ineffective symbiotic mutation was determined. The fine mapping and the isolation of the genes in question by map-based cloning are in progress.
Keywordsgenetic mapping map-based cloning Medicago sativa RFLP symbiotic nitrogen fixation leaf morphogenesis
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