Submitted to: Plant Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/1996
Publication Date: N/A
Technical Abstract: Cultivated alfalfa (Medicago sativa) is an autotetraploid. However, all three existing alfalfa genetic maps resulted from crosses of diploid alfalfa. A study was undertaken to evaluate the use of Simple Sequence Repeat (SSR) DNA markers for mapping diploid and tetraploid alfalfa. Ten SSR loci were incorporated into an existing F2 diploid alfalfa RFLP map, and were also mapped in an F2 tetraploid population. Following the segregation of alleles in the tetraploid mapping population generally was clear and easy. Linkage relationships at the tetraploid level were determined by using a single dose allele (SDA) analysis, where each allele is scored as a dominant marker independently of the other alleles at the same locus. The SDA diploid map was also constructed to compare mapping using SDA to the standard co-dominant method. Linkage groups were generally conserved among the tetraploid and the two diploid linkage maps, except for segments where severe segregation distortion was present. Segregation distortion which was present in both tetraploid and diploid populations probably resulted from inbreeding depression. Therefore, a better approach to map alfalfa would be in a non-inbred mapping population such as an F1. The ease of analysis together with the abundance of SSR loci in plant genomes indicated that SSR markers should be a useful tool for mapping in tetraploid alfalfa, as well as other autopolyploid species.