Karyotypic analysis of N-banded chromosomes of diploid alfalfa: Medicago sativa ssp. caerulea and ssp. falcata and their hybrid.
Chromosomes of two diploid (2n = 2x = 16) subspecies of Medicago sativa, ssp. caerulea and ssp. falcata, and their hybrid were studied using an N-banding technique. This study was undertaken to develop an N-banded karyotype of ssp. caerulea and ssp. falcata, and determine if the same technique could be used to identify parental chromosomes in hybrids. The chromosomes of ssp. falcata have only centromeric N bands and thus individual chromosomes could not be identified. However, chromosome-specific bands were observed in ssp. caerulea enabling the identification of each of the eight pairs of chromosomes and the development of an idiogram. All chromosomes have a centromeric band and a telomeric band in the short arm. All of the chromosomes, except chromosomes 7 and 8, have interstitial bands in their long arms and chromosome 5 has two faint interstitial bands in its long arm. The satellited chromosome is easily distinguished due to the secondary constriction and characteristic band at the nucleolar organizer region. The differences in banding patterns between these subspecies makes it possible to distinguish chromosomes from each other in their hybrids. This is the first report of the use of N banding to identify the diploid chromosomes of M. sativa ssp. caerulea and ssp. falcata.
Bauchan
G R
GR
USDA, Agricultural Research Service, Beltsville, MD 20705-2350, USA.
Hossain
M A
MA
D002503:Centromere / Q000235:genetics; D002871:Chromosome Banding; D002874:Chromosome Mapping; D004171:Diploidy; D006824:Hybridization, Genetic; D007621:Karyotyping; D000455:Medicago sativa / Q000235:genetics*; D009697:Nucleolus Organizer Region / Q000235:genetics; D013045:Species Specificity