Sequencing of species and strains of the Phytophthora to identify polymorphisms: Phytophthora infestans strain T30-4

Plant pathogens in the lineage of the Irish potato famine organism Phytophthora infestans evolve by host jumps and specialization. The extent to which host jumps and specialization impact genome evolution remains largely unknown. To determine the selective forces shaping sequence variation in this lineage, we sequenced six genomes of four sister species. This work revealed uneven evolutionary rates with genes in repeat-rich regions showing higher rates of copy number variation, presence/absence polymorphisms, and dN/dS=1. These loci are enriched in genes induced in planta implicating host adaptation in genome evolution. Genes involved in epigenetic processes are other rapidly evolving residents of the gene-sparse regions. These results demonstrate that dynamic genome compartments enriched in non-coding sequences underpin rapid gene evolution following host jumps in this pathogen lineage.