Seagrass genome sequence lends insights to salt tolerance

International team sequenced a seagrass genome: that of the eelgrass Zostera marina, taken from the Archipelago Sea off Finland.

Despite the name, eelgrasses aren't true grasses but rather completely submerged marine flowering plants, or angiosperms, and members of an ancient monocot family. To better understand the adaptations the plant made in returning to a saltwater environment, the team compared the eelgrass genome to its freshwater relative, Greater duckweed (Spirodela polyrhiza).

Found throughout the northern hemisphere, Zostera marina is the first marine flowering plant to be fully sequenced. As a foundational species in the coastal marine ecosystem, researchers are interested in understanding how the plant—and by extension other plants in the ecosystem—adapts to climate change.

In adapting to an underwater lifestyle, eelgrass gained genes that allowed it to live in saltwater but lost genes involved in traits associated with land-based plants. The team was interested in identifying the pathways that underwent major modifications upon Zostera marina's return to the sea.

Study lead author Jeanine Olsen of the University of Groningen in the Netherlands called this "arguably the most extreme adaptation a terrestrial (and even a freshwater) species can undergo." Following what she describes as the "use it, lose it, or change it" scenario, eelgrass has modified its cell walls—which are uniquely more seaweed-like—and genes associated with light-sensing, plant defense and signaling, pollination system and regulation of internal water balance.