Comparative genomics of Phaeocystis species to reveal cold adaptations

Phaeocystis are haptophyte algae dominating the world oceans in subpolar, temperate and tropical areas. Through the ability to form polysaccharide-embedded colonies in replete conditions, several species of Phaeocystis create massive blooms and thus participate as major players in the natural cycles of nutrients, notably carbon and sulfur. To underpin the ecological success of these microalgae, we created and annotated genomic data for 12 Phaeocystis sp. accessions. Using this data, we map the distribution of these species in world oceans and compare the “core” and “shell” gene repertoire of P. globosa pan-genome. Function-wise, our primary concern was to understand the nature of P. antarctica genetic capacity not contained in more temperate-water globosa species and to identify molecular processes involved in maintaining osmotic balance during exposure to freezing and low salinity during the Antarctic winter.