Transcriptome response of Antarctic Phaeodactylum tricornutum ICE-H producing dimethylsulphoniopropionate to hypersaline stress

Dimethylsulfoniopropionate (DMSP) is one of the most abundant organosulfur‐containing molecules on earth. The DMSP synthesis by microalgae is of great significance for understanding the large-scale feedback between marine phytoplankton and the atmospheric chemistry and physical environment. In this study, temperature 4 °C and salinity 32‰ were more suitable for the growth and biomass accumulation of Phaeodactylum tricornutum ICE-H. Additionally, the DMSP synthesized by P. tricornutum ICE-H mainly exists in the form of particles, and the high salt environment is beneficial to DMSP biosynthesis. RNA-seq analysis revealed that the response of P. tricornutum ICE-H to hypersaline stress is a systematic work at global transcriptomic level, which may involve enhancements of photosynthesis, carbon fixation and ion transport processes, accelerated protein turnover, as well as fatty acid metabolism, glycolysis/gluconeogenesis. Meanwhile, several candidate DMSP synthesis genes were found that belong to the enzyme classes of the proposed algal assimilatory sulfur reduction pathway and transamination pathway. In conclusion, all the changes in these biological processes will help to recognize the new balance of P. tricornutum ICE-H adapting to hypersaline environment, and further understand the mechanism of the polar microalgae adapting to extreme environment and its unique phylogenetic status in polar habitats.