| Popis: |
Seagrasses are an ecologically important group of plants that have returned to the sea from terrestrial ancestors on at least three occasions (Cymodoceaceae, Posidoniaceae, Zosteraceae). Seagrass-specific genomic adaptations to marine life are known from the Zosteraceae. However, independent lineages may have devised different solutions to life underwater. Here, we present two new genome assemblies from endemic Australian seagrasses,Amphibolis antarctica(Cymodoceaceae) andPosidonia australis(Posidoniaceae). We found large differences in genome size betweenAmphibolisandPosidoniadriven by repeat expansion inPosidonia. We show that parts of ethylene pathways known to be lost in Zosteraceae are partially retained in older seagrass lineages (Cymodoceaeceae and Posidoniaceae). We describe adaptations within salinity, disease resistance, cell wall, and photosynthesis-related pathways not shared with other seagrasses. These findings provide insight into the impact of recolonising marine environments on formerly terrestrial plant genomes, with some adaptations previously thought to be universal to marine living not having occurred inA. antarcticaandP. australis. |
