Seagrasses provide the foundation of highly productive ecosystems present along the coasts of all continents except Antarctica, where they rival tropical rain forests and coral reefs in ecosystem services. In colonizing sedimentary shorelines of the world's oceans, seagrasses found a vast new habitat free of terrestrial competitors and insect pests, but had to adapt to cope with new structural and physiological challenges related to full marine conditions. An international research team co-led by Jeanine Olsen (GELIFES, University of Groningen) and Yves Van de Peer (VIB, UGent) completed the first comprehensive genome analysis of Zostera marina, the most widespread seagrass species throughout the temperate northern hemisphere.
This study 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. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing. Seagrasses have also regained functions enabling them to adjust to full salinity.
The Zostera marina genome resource can markedly inspire a wide range of functional ecological studies. "Today, more and more people are inhabiting our planet's coastal areas. Consequently, many ecosystems are under pressure, including seagrass beds. As a result, other ecosystems may be at risk, too. Seagrasses not only sustain harvestable fish and invertebrates like lobsters, shrimp and crabs; they also play a part in controlling erosion effects and capturing carbon dioxide. Having unravelled the genomic basis of Zostera marina's complex adaptations to life in ocean waters, this study can advance ecological studies on how marine ecosystems might adapt under climate warming", Prof. Van de Peer says.
The findings were published in the advanced online edition of Nature.