Olsen JL, Rouzé P, Verhelst B, Lin YC, Bayer T, Collen J, Dattolo E, De Paoli E, Dittami S, Maumus F, Michel G, Kersting A, Lauritano C, Lohaus R, Töpel M, Tonon T, Vanneste K, Amirebrahimi M, Brakel J, Boström C, Chovatia M, Grimwood J, Jenkins JW, Jüterbock A, Mraz A, Stam WT, Tice H, Bornberg-Bauer E, Green PJ, Pearson GA, Procaccini G, Duarte CM, Schmutz J, Reusch TBH, van de Peer Y
The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea
Nature doi:10.1038/nature16548, 2016
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Seagrasses colonized the sea about 100 million years ago to form one of the most productive and widespread coastal ecosystems on the planet. The genome of Zostera. marina (L.), the first marine angiosperm to be fully sequenced, reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. A number of key angiosperm innovations were lost, such as the entire repertoire of stomatal genes, as well as key genes involved in the synthesis of terpenoids and ethylene signaling involved in aerial communication and resistance to insect herbivores through volatile organics. Additional reductions include the nucleotide binding site-leucine rich repeat (NBS-LRR) family involved in plant defense and loss of UV protection provided by UVR8 and phytochromes for far-red sensing. In contrast, seagrasses have also regained functions enabling them to adjust to full salinity and the altered light regimes of the marine environment. Cell walls are more algal-than plant-like, a feature important for osmoregulation and ion homoeostasis, as well as the capacity for nutrient uptake and gas exchange through leaf epidermal cells. Complex sulfated-polysaccharides and hemicelluloses re-appear as genes reminiscent of sulfated galactans in red algae and the co-existence of proton transporters and Na+/H+ antiporters maintain membrane potential against intrusion of Na+ from seawater and the pH imbalance created during carbonic anhydrase (CA)-mediated, bicarbonate transport for photosynthesis. The Z. marina genome resource will significantly advance a wide range of functional ecological studies from adaptation of marine ecosystems under climate warming to unravelling the mechanisms of osmoregulation that may accelerate the capacity of crop plants to be grown in seawater.