Abstract: The rDNA internal transcribed spacer 1 (ITS1) regions of wild soybean (Glycine soja), semiwild soybean (G. gracillis), perennial wild soybean (G. tomentella, G. tabacina) and two accessions of cultivated soybean (G. max) were amplified by PCR and cloned. The copy number in soybean genome was about 2 × 103. Sequence analysis showed that the G/C content of G. soja (61.40%), G. gracillis (61.40%), G. max (61.40%), G. tabacina (58.11%) and G. tomentella (59.01%) were very similar to that of Phaseolus radiatus (59.81%), and the G/C content of G. tabacina was the lowest one in all known ITS1 re- gions of plants. Maxium-homology analysis proved that the ITS1 sequence of soybean was the most homologous to its counterpart of P. radiatus. It was implied that the homology of ITS1 regions of relative species were related with the genetic relationships among these species. Sequence analysis disclosed that there were two conserved sequences (GACCCGC- GAA) and (GCGCCAAGGAA) in all sequenced ITS1 regions of plants.

Key words: Wild soybean, Cultivated soybean, rDNA internal transcribed spacer 1 region, Genetic relationship