Origin matters — Comparative transcriptomics in Saccharina latissima (Phaeophyceae)

• Sporophytes of Saccharina latissima were exposed for 24 h to UV-radiation at three different temperatures.
• Comparisons of gene expression profiles in field versus laboratory grown sporophytes were carried out.
• Field material reacted less intense than laboratory material on the basis of absolute numbers of responding genes.
• Principal effects of UV-radiation, targeting mainly photosynthesis and DNA, were similar in sporophytes of both origins.

Kelps, brown algae of the order Laminariales, dominate rocky shores of cold-temperate regions and constitute important components of coastal ecosystems. Factors influencing their distribution are light including UV-radiation, and temperature, therefore future global environmental changes will likely have an impact on their zonation, distribution patterns, and primary productivity. Here the question was addressed whether laboratory studies can allow such predictions on natural communities by exploring interactive effects of UV-radiation, temperature and growth conditions, on cultivated versus field sporophytes of Saccharina latissima. Both were exposed for 24 h to UV-radiation at three different temperatures (2, 7 & 12 °C), gene expression profiles under UV-radiation at different temperatures were assessed through microarray hybridizations, and comparisons of gene expression profiles in field versus culture sporophytes were carried out. Principal effects of UV-radiation were similar in culture and field sporophytes, demonstrating laboratory experiments being well suited for investigating basic molecular mechanisms of acclimation to abiotic stresses in the field. However, sporophytes from the field reacted less intense than laboratory cultures, indicating that the severity of transcriptomic responses in situ may be over-estimated from laboratory experiments.