Bigfoot: a new family of MITE elements characterized from the Medicago genus

We have characterized from the legume plant Medicago a new family of miniat ure inverted-repeat transposable elements (MITE) called the Bigfoot transpo sable elements. Two of these insertion elements are present only in a singl e allele of two different M. sativa genes. Using a PCR strategy we have iso lated 19 other Bigfoot elements from the M. sativa and M. truncatula genome s. They differ from the previously characterized MITEs by their sequence, a target site of 9 bp and a partially clustered genomic distribution. In add ition, we show that they exhibit a significantly stable secondary structure . These elements may represent up to 0.1% of the genome of the outcrossing Medicago sativa but are present at a reduced copy number in the genome of t he autogamous M. truncatula plant, revealing major differences in the genom e organization of these two plants.