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.