Chemical diversity of scleractinian corals revealed by untargeted metabolomics and molecular networking

The chemical diversity of scleractinian corals is closely related to their physiological, ecological, and evolutionary status, and can be influenced by both genetic background and environmental variables. To investigate intraspecific variation in the metabolites of these corals, the metabolomes of four species (Pocillopora meandrina, Seriatopora hystrix, Acropora formosa, and Fungia fungites) from the South China Sea were analyzed using untargeted mass spectrometry-based metabolomics. The results showed that a variety of metabolites, including amino acids, peptides, lipids, and other small molecules, were differentially distributed among the four species, leading to their significant separation in principal component analysis and hierarchical clustering plots. The higher content of storage lipids in branching corals (P. meandrina, S. hystrix, and A. formosa) compared to the solitary coral (F. fungites) may be due to the high densities of zooxanthellae in their tissues. The high content of aromatic amino acids in P. meandrina may help the coral protect against ultraviolet damage and promote growth in shallow seawater, while nitrogen-rich compounds may enable S. hystrix to survive in various challenging environments. The metabolites enriched in F. fungites, including amino acids, dipeptides, phospholipids, and other small molecules, may be related to the composition of the coral's mucus and its life-history, such as its ability to move freely and live solitarily. Studying the chemical diversity of scleractinian corals not only provides insight into their environmental adaptation, but also holds potential for the chemotaxonomy of corals and the discovery of novel bioactive natural products.