Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus.

Thomas Mock (1) , Robert P Otillar (2) , Jan Strauss , Mark Mcmullan , Pirita Paajanen , Jeremy Schmutz (3, 2) , Asaf Salamov (2) , Remo Sanges (4) , Andrew Toseland , Ben J Ward (5) , Andrew E Allen , Chris Dupont (6) , Stephan Frickenhaus (7) , Florian Maumus (8) , Alaguraj Veluchamy , Taoyang Wu (9) , Kerrie W Barry (10) , Angela Falciatore (11) , Maria I Ferrante (4) , Antonio E Fortunato (11) , Gernot Glöckner (12) , Ansgar Gruber (13) , Rachel Hipkin , Michael G Janech (14) , Peter G Kroth (15) , Florian Leese (16) , Erika A Lindquist (2) , Barbara R Lyon , Joel Martin , Chris Mayer , Micaela Parker (17) , Hadi Quesneville (8) , James A Raymond , Chris Uhlig , Ruben E Valas , Klaus U Valentin (7) , Alexandra Z Worden (18, 19, 20) , E Virginia Armbrust (21) , Matthew D Clark , Chris Bowler , Beverley R Green (22) , Vincent Moulton (23) , Cock van Oosterhout (24) , Igor V Grigoriev (25)

1 School of Environmental Sciences [Norwich]
2 Joint Genome Institute
3 Hudson Alpha Institute
4 Sezione Ecologia Marina Integrata
5 School of Physics [NUI Galway]
6 2I - Infection et inflammation
7 AWI - Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
8 URGI - Unité de Recherche Génomique Info
9 TUM - Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne]
10 United States Department of Energy
11 LCQB - Biologie Computationnelle et Quantitative = Laboratory of Computational and Quantitative Biology
12 Genomics Institute for Biochemistry I
13 Leopold Franzens Universität Innsbruck - University of Innsbruck
14 Laboratoire Genome Population & Interactions
15 Department of Biology
16 Animal Ecology, Evolution and Biodiversity
17 Univ Reading, Sch Chem Pharm & Food Biosci, Reading RG6 6AD, Berks, England
18 CIFAR - Canadian Institute for Advanced Research
19 MBARI - Monterey Bay Aquarium Research Institute
20 UC Santa Cruz - University of California [Santa Cruz]
21 School of Oceanography [Seattle]
22 Johns Hopkins University School of Medicine [Baltimore]
23 Department of Computer Science
24 UEA - University of East Anglia [Norwich]
25 DOE Joint Genome Institute [Walnut Creek]

The Southern Ocean houses a diverse and productive community of organisms. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean.

Domains: Life Sciences [q-bio]

Thomas Mock, Robert P Otillar, Jan Strauss, Mark Mcmullan, Pirita Paajanen, et al.. Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus.. Nature, 2017, 541, pp.536-540. ⟨10.1038/nature20803⟩. ⟨hal-01587937⟩