Phenotypic plasticity in coral skeletal features: Molecular signatures from DNA methylation and transcriptional interaction networks

Acclimation through phenotypic plasticity represents a more rapid response to environmental change than adaptation and is vital to optimize organisms’ performance in different conditions. Generally, animals are less phenotypically plastic than plants, but reef-building corals exhibit plant properties. They are light-dependent with a sessile and modular construction that facilitates rapid morphological changes within their lifetime. We induced phenotypic changes by altering light exposure in a reciprocal transplant experiment and found that coral plasticity is a colony trait emerging from comprehensive morphological and physiological changes at the local level. Plasticity in skeletal features optimized coral light harvesting and utilization and paralleled with significant methylome and transcriptome modifications. Network-associated responses resulted in the identification of hub genes and clusters associated to the change in phenotype: inter-partner recognition and phagocytosis, soft tissue growth and biomineralization. Furthermore, we identified hub genes putatively involved in animal photoreception-phototransduction. These findings fundamentally alter our understanding of how cnidarian invertebrates repattern the methylome and adjust a phenotype, revealing an important role of light sensing by the coral animal to optimize photosynthetic performance of the symbionts.