PT  - JOURNAL ARTICLE
AU  - Simon M. Dittami
AU  - Erwan Corre
AU  - Loraine Brillet-Guéguen
AU  - Noé Pontoizeau
AU  - Meziane Aite
AU  - Komlan Avia
AU  - Christophe Caron
AU  - Chung Hyun Cho
AU  - Jonas Collén
AU  - Alexandre Cormier
AU  - Ludovic Delage
AU  - Sylvie Doubleau
AU  - Clémence Frioux
AU  - Angélique Gobet
AU  - Irene González-Navarrete
AU  - Agnès Groisillier
AU  - Cécile Hervé
AU  - Didier Jollivet
AU  - Hetty KleinJan
AU  - Catherine Leblanc
AU  - Agnieszka P. Lipinska
AU  - Xi Liu
AU  - Dominique Marie
AU  - Gabriel V. Markov
AU  - André E. Minoche
AU  - Misharl Monsoor
AU  - Pierre Pericard
AU  - Marie-Mathilde Perrineau
AU  - Akira F. Peters
AU  - Anne Siegel
AU  - Amandine Siméon
AU  - Camille Trottier
AU  - Hwan Su Yoon
AU  - Heinz Himmelbauer
AU  - Catherine Boyen
AU  - Thierry Tonon
TI  - The genome of <em>Ectocarpus subulatus</em> highlights unique mechanisms for stress tolerance in brown algae
AID  - 10.1101/307165
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 307165
4099  - http://biorxiv.org/content/early/2018/08/28/307165.short
4100  - http://biorxiv.org/content/early/2018/08/28/307165.full
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.