The green algal genus Ulva Linnaeus (Ulvaceae, Ulvales, Chlorophyta) displays a worldwide
distribution in marine, freshwater and brackish ecosystems, and are really well adapted to
fluctuating natural environments. Despite increasing interest on the analysis of the
ecophysiological responses showed by organisms to face environmental shifts, knowledge of
the genetic and molecular mechanisms underlying those responses are still scarce. These
responses determine the survival of organisms under pressure of different environmental
stresses and the regular ecosystem behaviour. In order to disentangle the genetic networks that
might regulate the adaptation mechanisms of these organisms in a changing environment, the
characterization of the de novo transcriptome from Ulva lacinulata derived from a coastal
ecosystems of southern Spain under in situ cyclic conditions of emersion/immersion by using
Next Generation Sequencing technologies was carried out. Transcriptome sequencing and
transcript-level expression analysis were performed by Illumina®NextSeq® 550 system
platform. A total of 100,251 unigenes were expressed during emersion/immersion process.
Based on the differentially expressed genes (DEGs), genes associated with different
biosynthetic metabolic pathways were annotated according to Gene Ontology and Kyoto
Encyclopedia of Genes and Genomes Orthology (KEGG). These findings shed light on the
molecular mechanisms underlying rapid and successful ecophysiological response of marine
macroalgae in cyclic tidal conditions.