Gene expression analysis in the green macroalga Acrosiphonia arcta (Dillw.) J. Ag.: Method optimization and influence of ultraviolet radiation

Marine macroalgae represent an important part of coastal ecosystems in temperate and polar areas. Increasing surface ultraviolet radiation (UVR) levels due to stratospheric ozone thinning may lead to deleterious effects on the physiology of marine macroalgae. Only few studies concentrate on the response of macroalgal gene expression towards elevated UVR. Analyzing gene expression in marine algae is challenging regarding RNA extraction, enrichment of differentially expressed transcripts and identification of resulting sequences. Thus, we focused on the optimization of the appropriate techniques using the widely distributed green marine macroalga Acrosiphonia arcta. We successfully used a combination of suppression subtractive hybridization with microarray‐based screening of size‐selected cDNA libraries and were able to substantially improve the outcome compared with standard techniques. Analysis of differential gene expression revealed a distinct pattern of reactions towards ecologically relevant UVR levels pointing to specific mechanisms that include modulation of the photosynthetic apparatus, induction of glutathione metabolism, removal of toxic photoproducts and use of the malate valve to dissipate excess energy. The results of this study clearly correlate with previous physiological findings on photosynthesis and the antioxidative capacity of this alga.