Genome organization in Fusarium oxysporum: clusters of class II transposons

Several families of transposable elements (TEs) are present in the genome o f the phytopathogenic fungus Fusarium oxysporum. They are present in copy n umbers ranging from just a few elements to tens or hundreds per genome, Seq uence analysis of contiguous stretches of genomic DNA surrounding insertion sites of one family revealed that they are packed with repeated sequences. We have carried out a detailed study of the composition and arrangement of these repeats in three chromosomal regions. We found that they are essenti ally mixtures of several types of TEs, most of them being DNA transposons, different from those previously characterized. Some repeats are frequently reiterated and many of them are inserted into other elements. Parts of thes e regions are also duplications. These regions appear prone to rearrangemen t and transposition and are subject to rapid reorganization.