Phylogenetic, Ecological and Physiological characterisation of the pan-Arctic algal genome – PanArctica

The Arctic Ocean is set apart from all other oceans due to being encircled by land, its extreme environment, and its distinct ecosystem, characterised by strong seasonal succession. Anthropogenic climate change is rapidly changing the Arctic Ocean into a warmer, fresher habitat, and understanding the biological communities that support the Arctic is urgent for projecting its future robustness.

The PI, Richard Dorrell, is a specialist in the evolutionary diversity of eukaryotic microalgae, which through photosynthesis support the entire Arctic food chain. Previously, Dr. Dorrell has demonstrated using comparative genomics that distantly related Arctic algae have converged on similar functions, which in part is mediated through the direct exchange of genes between Arctic species. These data provide some of the first systematic insights into the pan-Arctic algal genome ; and reposition our understanding of horizontal gene transfer from an ancient process to an effector of rapid environmental adaptation.

Here, Dr. Dorrell will leverage new genome resources, including environmental sequence data from the Tara Oceans Expedition ; and functional physiology of the model diatom species Phaeodactylum ; to explore systematically what genes allow different algae to thrive in the Arctic Ocean. First, Dr. Dorrell will generate mass transcriptome data, from algae from a variety of Arctic habitats, including sea-ice, open-water, and different Arctic seas. Dr. Dorrell will perform high-throughput phylogenomics on these and other Arctic algal sequence data to understand what genes underpin the specialisation of algae to different Arctic eco-physiological niches, focussing on Arctic-specific genes, and within-Arctic horizontal gene transfers.

Next, Dr. Dorrell will use integrate transcriptome, lipid and metabolite measurements to understand how Phaeodactylum 1.86, which is typically associated with temperate habitats, acclimates to constitutive low temperatures, continuous illumination, and low salinities as found in the Arctic. Finally, Dr. Dorrell will explore the functions of Arctic-specific, and Arctic-adaptive genes identified using each approach via classical mutagenesis ; using environmental sequence datasets to predict and interpret mutant phenotypes. In a preliminary project, Dr. Dorrell has shown for example that a complete chloroplast glycolytic pathway defines diatom adaptations to high latitudes ; and that mutant Phaeodactylum lines for key chloroplast effectors show compromised growth under low temperatures and continuous illumination.

The data obtained from this project will provide in-depth insights into the functional biology of an important and rapidly changing oceanic habitat. In the long term, these may allow more refined understanding of which species will proliferate in the future Arctic Ocean. In addition, proteins identified that confer temperature, salinity and photo-tolerance in Arctic native species may be explored as candidates for improving the productivity and robustness of biofuels and other cultivable crop species.