Subrepeats located in the rDNA intergenic spacer are also present as independently occurring, tandemly arranged satellite DNA clusters in the genome of Vigna radiata (mung bean). These 174-bp satellite repeats are identified as non-rDNA repeats by the presence of an AluI site. In the closely related Vigna angularis (adzuki bean), 174-bp repeats characterized by an AluI site occur in the rDNA with high sequence homology to the V. radiata rDNA subrepeats. A part of the 174-bp element that shows high similarity to a Xenopus terminator box (T2/T3) is slightly modified in V. angularis. However, a characteristic stem-loop structure can be formed, as in the case of V. radiata. Two highly conserved 12-bp regions occur within the 174-bp rDNA repeats of the two plants investigated. One of these 12-bp stretches exhibits some sequence identity to an element repeated twice in the 325-bp repeats in the intergenic spacer region of Vicia faba (broad bean).