Transcriptomic analyses of kelps - endophytes cocultures.. Kelps-endophytes transcriptomics

The algal endophyte Laminarionema elsbetiae is highly prevalent in European populations of the sugar kelp, Saccharina latissima, but has also been found occasionally in the finger kelp Laminaria digitata. The presence of L. elsbetiae coincides with morphological changes in the hosts, however, little is known about the molecular bases of this interaction. Co-cultivation experiments were set up to monitor the impact of the endophyte on the gene transcription regulation of S. latissima or L. digitata after a first contact with L. elsbetiae in laboratory-controlled conditions. Spores of fertile individuals of S. latissima and L. digitata, collected at Perharidy (near Roscoff, 48.73° N, 4.00° W) were released in laboratory and used to grow sporophytes in filtered, autoclaved natural seawater, enriched with Provasoli solution, in 14°C and 20 μmol photons s-1.m-2 with a 12 h light/dark cycle. Cultures of the filamentous brown algae Laminarionema elsbetiae were obtained from the Bezhin Rosko culture collection, and kept in petri dishes in 14°C and 5 μmol photons s-1.m-2. For the experiment, 12 young sporophytes of S. latissima or L. digitata (3-5cm) were transferred to 12 2-L bottles, filled with 1.5 L sterile Provasoli-enriched natural seawater and connected to an aeriation system. After 24 h of adaptation time, half of individual sporophytes (three independent biological replicates for each species, 2 time points) were incubated with a filament of L. elsbetiae, when control sporophytes were maintained in the same conditions. Three individuals of the control group and three individuals co-cultivated with L. elsbetiae were taken after 24h and 48h, frozen in liquid nitrogen and used for RNA extraction and Illumina sequencing.