RT Journal Article SR Electronic T1 The genome of Ectocarpus subulatus highlights unique mechanisms for stress tolerance in brown algae JF bioRxiv FD Cold Spring Harbor Laboratory SP 307165 DO 10.1101/307165 A1 Simon M. Dittami A1 Erwan Corre A1 Loraine Brillet-Guéguen A1 Noé Pontoizeau A1 Meziane Aite A1 Komlan Avia A1 Christophe Caron A1 Chung Hyun Cho A1 Jonas Collén A1 Alexandre Cormier A1 Ludovic Delage A1 Sylvie Doubleau A1 Clémence Frioux A1 Angélique Gobet A1 Irene González-Navarrete A1 Agnès Groisillier A1 Cécile Hervé A1 Didier Jollivet A1 Hetty KleinJan A1 Catherine Leblanc A1 Agnieszka P. Lipinska A1 Xi Liu A1 Dominique Marie A1 Gabriel V. Markov A1 André E. Minoche A1 Misharl Monsoor A1 Pierre Pericard A1 Marie-Mathilde Perrineau A1 Akira F. Peters A1 Anne Siegel A1 Amandine Siméon A1 Camille Trottier A1 Hwan Su Yoon A1 Heinz Himmelbauer A1 Catherine Boyen A1 Thierry Tonon YR 2018 UL http://biorxiv.org/content/early/2018/08/28/307165.abstract AB Brown algae are multicellular photosynthetic organisms belonging to the stramenopile lineage. They are successful colonizers of marine rocky shores world-wide. The genus Ectocarpus, and especially strain Ec32, has been established as a genetic and genomic model for brown algae. A related species, Ectocarpus subulatus Kützing, is characterized by its high tolerance of abiotic stress. Here we present the genome and metabolic network of a haploid male strain of E. subulatus, establishing it as a comparative model to study the genomic bases of stress tolerance in Ectocarpus. Our analyses indicate that E. subulatus has separated from Ectocarpus sp. Ec32 via allopatric speciation. Since this event, its genome has been shaped by the activity of viruses and large retrotransposons, which in the case of chlorophyll-binding proteins, may be related to the expansion of this gene family. We have identified a number of further genes that we suspect to contribute to stress tolerance in E. subulatus, including an expanded family of heat shock proteins, the reduction of genes involved in the production of halogenated defense compounds, and the presence of fewer cell wall polysaccharide-modifying enzymes. However, 96% of genes that differed between the two examined Ectocarpus species, as well as 92% of genes under positive selection, were found to be lineage-specific and encode proteins of unknown function. This underlines the uniqueness of brown algae with respect to their stress tolerance mechanisms as well as the significance of establishing E. subulatus as a comparative model for future functional studies.