Genome size of man and animals relative to the plant Allium cepa.

A direct Feulgen-cytophotometric comparison of the genomic DNA content (C value) was performed between the liliaceous plant species Allium cepa and a number of animal species to reassess the genome size ratios between plants and animals. These appeared unduly ambiguous as a consequence of divergent picogram estimates in several animal reference species. Taking 1C = 16.75 pg for Allium cepa, the estimates were (1C value in picograms): man, 3.11; Indian muntjak CCL 157 cell line, 2.68; domestic pig, 2.79; Chinese hamster, 2.66; CHO cell line, 2.73; laboratory rat, 2.65; mouse, 3.04; rat kangaroo Pt-K2 cell line, 4.21; fowl, 1.16; and the green toad, 4.30. These values are consistent with a number of independent absolute and relative DNA content determinations reported for animals, and therefore define a coherent set of animal and plant reference values for genome size determinations.