Characterization and transcriptional analysis of one carbonic anhydrase gene in the green-tide-forming alga Ulva prolifera (Ulvophyceae, Chlorophyta)

Ulva prolifera is a green-tide-forming macroalga dominating the green tides in the Yellow Sea from 2007 to 2019. The exponential growth of U. prolifera, and the correlating accumulation of biomass, rely heavily on its carbon fixation capability. Despite the importance of carbon fixation in algal growth, to date none of the genes involved in carbon fixation have undergone molecular characterization in U. prolifera. This study used Rapid Amplification of cDNA Ends (RACE) to characterize one full-length carbonic anhydrase (CA) gene of U. prolifera (Up alpha CA1). An activity assay showed that Up alpha CA1 was an active CA. Real-time quantitative PCR results showed that temperature, irradiance, salinity and pH could influence the transcriptional level of Up alpha CA1, indicating that Up alpha CA1 was sensitive to varying environmental factors. The results of this study provided further insights into our understanding of the influence of environmental factors on carbon fixation in U. prolifera and its subsequent role in the formation of green tides.