16S amplicon sequencing to assess the phenotypic plasticity of a major reef-building coral

Coral phenotypic plasticity is a prevalent phenomenon that enables corals to acclimate and adapt to environmental changes. Corals commonly exhibit a variety of color morphs, yet, the biological and ecological implications of such phenotypic variation remain unclear. In this study, the metabolome, proteome, bacterial communities, and Symbiodinaceae of two dominant color morphs (pink and brown) of healthy Pocillopora verrucosa were analyzed using a multi-omics approach along a latitudinal gradient in the Central Red Sea. Bacterial communities and Symbiodinaceae were similar within color morphs and across reefs. Notably, bacterial biomarkers associated with the pink morph included putative pathogens such as Salmonella, Escherichia-Shigella, and carotenoid pigment-producing bacteria of the genus Gemmatimonas. In contrast, the brown morph was associated with putative beneficial bacteria, such as Lysobacter, Acinetobacter, and Endozoicomonas. The lipidome and metabolome of P. verrucosa were remarkably homogeneous between color morphs, and consistent across the studied locations, suggesting similar metabolic performances during summer conditions. Fatty acids, Glycerophosphocholines, and retinoids were the major classes of apolar and polar metabolites. Notably, comparative proteomics revealed differential activation of the immune system and stress response in the pink morph, possibly associated with a major susceptibility to pathogens and environmental stress. In addition, a distinct cluster of Gfp-like proteins associated with host pigments was highly expressed in the pink morph. Heat shock proteins were more abundant in the brown morph, suggesting different physiological responses to cope with summer temperatures in the Red Sea. This study provides novel insights into the phenotypic plasticity of reef-building corals, underpinning color morphs in vivo physiological responses, shedding light into their potential trade-offs and acclimation strategies to thrive in a changing ocean.