The diversity of BARE-1 LTRs was studied by examining 24 sequences from 5 different Hordeum species. They differ mainly in their central and 3' regions. The first variable region is located around TATA box 2. TATA2 is necessary for the activity of the promoter in barley protoplasts, for which most of this variable region has been shown to be important. These results suggest that the promoters of type I and II could be activated under differing conditions.
Additional data indicate the existence of recombination between LTRs.
This mechanism has been proposed to give rise to the BARE-1 solo LTRs, very abundant in the Hordeum genomes.