A family of repeated DNA in the genome of the oomycete plant pathogen Phytophthora cryptogea

Abstract

We have identified a family of repetitive sequences, called PCISs (Phytophthora Cryptogea Insertion Sequences), in the genome of Phytophthora cryptogea. They vary greatly in size (in a 100-1200 bp range) and appear to represent 3' terminal fragments of a larger element. Two subfamilies were characterised on the basis of nucleotide sequences. PCISs exhibit insertion polymorphism, as well as a very low sequence divergence. Most copies are flanked by terminal direct repeats, suggesting that their spreading involves insertion events rather than rearrangements. PCISs are found in very few copies in Phytophthora cinnamomi. The spreading of these sequences within the genus Phytophthora is discussed.