There are basically two sets of 5S rRNA loci within the Triticeae. One set, identified by repetitive units 320-468 bp in length, is located in group 1 chromosomes. The other set, identified by repetitive units 469-500 bp in length, is in group 5 chromosomes. Within species, the repetitive units at a locus are extremely uniform in size and sequence. They remain stable in foreign genetic backgrounds.
A single 5S rRNA hybridization site was observed in barley. The chromosome involved was not one of those identified by the presence of secondary constrictions (34), but Kolchinsky et al. (514) located a predominant short repetitive sequence (320 bp) in 2H.
Wheat Gene Catalog Reference
Kolchinsky A et al. (1990) 5S-RNA genes of barley are located on the second chromosome. Theoretical and Applied Genetics 80:333-336.