Variation of DNA Content in the Genus Glycine

We examined the variation of DNA content in six Glycine species. DNA amount was estimated through Feulgen microspectrophotometry and chemical extraction. Glycine soja, known as the wild ancestor of G.max, has higher DNA content than G.tnax, although some overlapping occurs. Therefore, cellular DNA content has been reduced during the course of soybean domestication. As G.tabacina and tomentella contain both diploid and tetraploid strains, the interspecific variation was examined based on DNA content per chromosome. Glycinc soja has more chromosomal DNA than G.tabacina and probably other wild species. Therefore, we can conclude that the wild species, G.soja which has relatively high chromosomal DNA amount among wild relatives, was domesticated to the cultivated soybean. We consider that the relatively high DNA content of G, soja has enabled the wide genetic variation resulting in the formation of soybean through the reduction of DNA. The reduction of DNA amount through domestication will be also expected in other crops than soybean and rice.