Karyotypic analysis was conducted utilizing a computerized image analysis system of C-banded chromosomes of the nine germplasm sources of tetraploid alfalfa (Medicago sativa L.)(Barnes et.al. 1977). These nine germplasm sources were designated by the Alfalfa Crop Germplasm Committee as the populations which represent most of the alfalfa germplasm that has been used to develop modern alfalfa varieties. The PI's which were used in this study are: 'Falcata' PI 536531, 'Ladak' PI 536532, 'Varia' PI 536533, 'Chilean' PI 536534, 'Peruvian' PI 536535, 'Indian' PI 536536, 'Turkistan' PI 536537, 'Flemish' PI 536538, and 'African' PI 536539. The seeds for this study were obtained from the National Plant Germplasm System in Pullman, WA. The C-banding technique and computerized image analysis system utilized in this study are described by Bauchan and Hossain (1997). Karyotypic analysis of tetraploid alfalfa revealed that alfalfa has four nearly identical sets of chromosomes based on their chromosome morphology and C banding patterns, thus providing support that alfalfa is an autotetraploid. C-banding polymorphisms were detected in the number, position and intensity of terminal and interstitial bands within a germplasm source. A wide range of differences were also observed between the nine germplasm sources. The 'Falcata's source is strikingly different from other germplasm sources due to a fewer number of terminal and interstitial bands. 'Falcata' chromosomes have primarily C-bands at their centromere. The 'African' germplasm has the largest number of C-bands thus far studied with all of the chromosomes having centromeric bands, and in addition, all of the chromosomes have telomeric bands on their short arms. Except for chromosome 7, all of the chromosomes have interstitial bands on their short arms and chromosomes 1, 2 and 3 each have one prominent interstitial band on their long arms. The ranking of germplasm sources from greatest number of C-bands to least number of bands studied thus far is as follows:'African'>'Peruvian'>'Chilean'>'Flemish>'Indian'>'Varia '>'Ladak'>'Turkistan'>'Falcata'. It is interesting to note that the more winter hardy germplasm sources have fewer C-bands indicating the incorporation of 'Falcata' germplasm in alfalfa.
Bauchan GR and Hossain MA, 1997. Karyotypic analysis of C-banded chromosomes of diploid alfalfa: Medicago sativa ssp. caerulea and ssp. falcata and their hybrid. J Hered. 88:533-536.