The genome sequences of Achlya hypogyna and Thraustotheca clavata. Achlya hypogyna

Oomycetes offer a unique opportunity to explore the genomic consequences of evolving a parasitic lifestyle as the group contains closely related free-living and parasitic members. Using next-generation sequencing technology we sequenced the genomes of two saprolegnialean oomycetes, facultative parasite Achlya hypogyna and free-living Thraustotheca clavata. By increasing the genomic data available from the Saprolegniales and adding a free-living organism we were able to conduct comparative genomic analyses across phylogenetic and lifestyle barriers. Using evolutionary gene networks and gene family clustering algorithms we identified differentially occurring functional groups between these life history strategies, highlighting some of the processes behind parasite evolution in this enigmatic group. An examination of repetitive elements reveals that parasite genomes harbor an increased collection of these features that may play a crucial role in the evolution of novel genes involved in parasitism. Whereas lifestyle pressures have shaped extant oomycete genomes, phylogenetic barriers have a strong influence on proteome composition and function.