Characterization of repetitive DNA elements in Arabidopsis

We have applied computational methods to the available database and identif ied several families of repetitive DNA elements in the Arabidopsis thaliana genome. While some of the elements have features expected of either miniat ure inverted-repeat transposable elements (MITEs) or retrotransposons, the most abundant class of repetitive elements, the AthE1 family, is structural ly related to neither. The AthE1 family members are defined by conserved 5' and 3' sequences, but these terminal sequences do not represent either inv erted or direct repeats. AthE1 family members with greater than 98% identit y are easily identified on different Arabidopsis chromosomes. Similar to no nautonomous DNA-based transposon families, the AthE1 family contains member s in which the conserved terminal domains flank unrelated sequences. The pr imary utility of characterizing repetitive sequences is in defining, at lea st in part, the evolutionary architecture of specific Arabidopsis(lsis loci . The repetitive elements described here make up approximately 1% of the av ailable Arabidopsis thaliana genomic sequence.