Ploidy of embryogenic Medicago sativa subsp falcata germplasms

The germplasms Medicago sativa L. subsp. falcata WY-RF1 (Reg. no. GP-263, PI 564263) and WY-RF2 (Reg. no. GP-264, PI 564262), maintained at the Wyoming Agricultural Experimental Station, were reported to have improved regeneration capacity, to be embryogenic and are registered as diploid. We show that, in fact, germplasm WY-RF1 is diploid but WY-RF2 is tetraploid. The latter is more vigorous, but the two have close flowering times. The mean 2C nuclear DNA values from flow cytometry using ethidium bromide, verified upon many seeds including those from descendants, were: 1.88 pg for RFI. (1C = 907 million base pairs) and 3.41 pg for RF2 (1C = 1645 million base pairs). Chromosome numbers in root meristem metaphases were, respectively, 2n = 16 and 32. This distinction is capital for biotechnological and genetic studies. ((C) Inra/Elsevier, Paris.).