Gene Expression Profiles of Two Coral Species with Varied Resistance to Ocean Acidification

Recent studies have indicated that various corals might have different degrees of resistance to elevated CO2 levels. However, the underlying molecular mechanism accounting for these differences is still poorly understood. In this study, RNA-seq data were analyzed to identify differentially expressed genes in two coral species (Acropora austera and Acropora cerealis) in response to high CO2 levels. The calcification rates were higher in high CO2 treatment than the control in A. austera, but was not significantly different in A. cerealis. A KEGG database search revealed that in both coral species, most Ca2+ transporters were present in the calcium signaling pathway, which could be important in the CO2 regulation of coral calcification. The gene expression levels of many CO2 and HCO3- transporters were not affected by elevated CO2. Nevertheless, high CO2 levels did have an effect on the expression of certain Ca2+ transporters. The upregulation of Ca2+ transporters likely explained the higher resistance of A. austera to high CO2 than A. cerealis.