De novo transcriptome of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta) in response to temperature stress

Gracilariopsis tenuifrons is an agarophyte red alga of economic importance that is widely distributed along 7,900 km of the Brazilian coast. Due to its wide distribution, populations of Gp. tenuifrons are subjected to a wide range of environmental conditions, including different temperatures. According to IPCC forecasts, the sea surface temperature is likely to increase by at least 1.5 to 2C by 2050, and it is important to understand how susceptible tropical seaweeds will be to this change. To evaluate the effects of temperature on Gp. tenuifrons, we analysed gene expression profiles at two different temperatures, its optimal temperature of 25C and a stress temperature of 33C. Under the stress temperature conditions only a relatively small percentage of genes were differentially expressed compared to the optimal temperature (5.75% were down-regulated and 5.25% were upregulated at 33C). Analysis of the predicted functions of the differentially regulated genes indicated enrichment in DNA-associated processes for the upregulated genes and enrichment in gene ontogeny categories related to photosynthesis and membrane-associated processes for the down-regulated genes. Genomic information is still scarce for red algae and this study adds to our knowledge of the effects of temperature on macroalgae at the transcriptomic level.