BACKGROUND: Revolver is a newly discovered multi-gene family of transposable 
elements in the Triticeae genome. Revolver encompasses 2929 to 3041 bp, has 20 
bp of terminal inverted repeated sequences at both ends, and contains a 
transcriptionally active gene encoding a DNA-binding-like protein. A putative 
TATA box is located at base 221, with a cap site at base 261 and a possible 
polyadenylation signal AATAAA at base 2918. Revolver shows considerable 
quantitative variation in wheat and its relatives.
RESULTS: Revolver cDNAs varied between 395 and 2,182 bp in length. The first 
exon exhibited length variation, but the second and third exons were almost 
identical. These variants in the Revolver family shared the downstream region of 
the second intron, but varied structurally at the 5' first exon. There were 58 
clones, which showed partial homology to Revolver, among 440,000 expressed 
sequence tagged (EST) clones sourced from Triticeae. In these Revolver 
homologues with lengths of 360-744 bp, the portion after the 2nd exon was 
conserved (65-79% homology), but the 1st exon sequences had mutually low 
homology, with mutations classified into 12 types, and did not have EST 
sequences with open reading frames (ORFs). By PCR with the 3'-flanking region of 
a typical genomic clone of Revolver-2 used as a single primer, rye chromosomes 
1R and 5R could be simultaneously identified. Extensive eco-geographic diversity 
and divergence was observed among 161 genotypes of the single species Triticum 
dicoccoides collected from 18 populations in Israel with varying exposures to 
abiotic and biotic stresses (soil, temperature, altitude, water availability, 
and pathogens).
CONCLUSIONS: On the base of existing differences between Revolver variants, the 
molecular markers that can distinguish different rye chromosomes were developed. 
Eco-geographic diversification of wild emmer T. dicoccoides in Israel and high 
Revolver copy numbers are associated with higher rainfall and biotic stresses. 
The remarkable quantitative differences among copy numbers of Revolver in the 
same species from different ecosystems suggest strong amplification activity 
within the last 10,000 years. It is the interesting finding because the majority 
of Triticeae high-copy transposable elements seem to be inactive at the recent 
time except for BARE-1 element in Hordeum and the fact might be interesting to 
perceive the processes of plant adaptive evolution.