Karyotypic Analysis of C-Banded Chromosomes of Diploid Alfalfa: Medicago sativa ssp. caerulea and ssp. falcata and Their Hybrid

Abstract

Chromosomes of two diploid (2n = 2x = 16) subspecies of Medicago sativa ssp. caerulea and ssp. falcata and their hybrid were studied by C-banding. This study was undertaken to improve the C-banding technique for alfalfa chromosomes, develop a C-banded karyotype of the ssp. caerulea and ssp. falcata, and determine if the same C-banding technique could be used to identify parental chromosomes in hybrids. The chromosomes of ssp. falcata have only centromeric bands and thus individual chromosomes could not be identified. One accession of ssp. falcata displayed an interstitial band in the middle of the long arm on the satellite chromosome. However, chromosome-specific bands were observed in ssp. caerulea enabling the identification of each of the eight pairs of chromosomes and the development of a idiogram. All chromosomes had centromeric bands and a terminal band in the short arm except the satellite chromosome (chromosome 8). Interstitial bands were also observed in the short arms, with the exception of chromosome 7. Chromosomes 1, 2, 3, and 8 each had one prominent interstitial band in their long arm. The satellited chromosome is easy to identify because of the presence of the secondary constriction, two bands located on either side of the nucleolar organizer region, and a large terminal band on its long arm. The differences in banding patterns between these subspecies allowed the identification of parental chromosomes in hybrid cells.

Inbreeding Depression for Fertility and Biomass in Advanced Generations of Inter‐ and Intrasubspecific Hybrids of Tetraploid Alfalfa

“…caerulea [Bauchan and Hossain, 2001]) and M. sativa subsp. falcata (Bauchan and Hossain, 1997). Thus, while these two results are limited in their scope, they suggested that chromosomal differences could exist between subspecies and that these could affect the progeny of SFC.…”

Relationships among Diploid Members of the Medicago sativa (Fabaceae) Species Complex Based on Chloroplast and Mitochondrial DNA Sequences

“…glomerata , which they considered to be the ancestor of "caerulea" and "falcata." These two diploid taxa also have cytogenetic differences as shown in their C-banding karyotypes ( Bauchan and Hossain 1997 ).…”

Distribution and Characterization of Heterochromatic DNA in the Tetraploid African Population Alfalfa Genome

“…coerulea and subsp. falcata by their unique banding patterns using C‐banding (Bauchan and Hossain, 1997, 1999a). Falistocco et al (1995) reported the first C‐banded karyotype of tetraploid alfalfa based on the Italian cultivar ‘Turrena’.…”