Clustered and dispersed chromosomal distribution of the two classes of Revolver transposon family in rye (Secale cereale).

The chromosomal locations of a new class of Revolver transposon-like elements were analyzed by using FISH method on the metaphase chromosome in somatic cell division of the rye cultivar Petkus. First, the Revolver standard element probe λ2 was weakly hybridized throughout the rye chromosome, and comparatively large interstitial signals spotted with a dot shape were detected together with several telomeric regions. The dot shape interstitial signal was stably detected at one site on Chromosome (Chr) 1R (middle part of the interstitial region of the short arm), three sites on Chr 2R (distal part of the interstitial region and adjacent to the centromere on the short arm, middle part of the interstitial region of the long arm), and two sites on Chr 5R (middle part of the interstitial region and adjacent to the centromere on the long arm). The Revolver λ2 probe was effective for identification of 1R, 2R, and 5R chromosomes. On the other hand, Revolver nonautonomous element-specific L626-BARE-100 probe was strongly distributed throughout the rye chromosomes, and considerable numbers and diverse lengths of transcripts were detected by RT-PCR. Although the standard elements were found in localized clusters, the nonautonomous elements tended to be dispersed throughout the genome. Clustered nature of Revolver is a significantly rare case in genomics.