Unlocking the Complex Cell Biology of Coral-Dinoflagellate Symbiosis: A Model Systems Approach.

Symbiotic interactions occur in all domains of life, providing organisms with resources to adapt to new habitats. A prime example is the endosymbiosis between corals and photosynthetic dinoflagellates. Eukaryotic dinoflagellate symbionts reside inside coral cells and transfer essential nutrients to their hosts, driving the productivity of the most biodiverse marine ecosystem. Recent advances in molecular and genomic characterization have revealed symbiosis-specific genes and mechanisms shared among symbiotic cnidarians. In this review, we focus on the cellular and molecular processes that underpin the interaction between symbiont and host. We discuss symbiont acquisition via phagocytosis, modulation of host innate immunity, symbiont integration into host cell metabolism, and nutrient exchange as a fundamental aspect of stable symbiotic associations. We emphasize the importance of using model systems to dissect the cellular complexity of endosymbiosis, which ultimately serves as the basis for understanding its ecology and capacity to adapt in the face of climate change.