Meeting Abstract
Symbioses with unicellular algae in the family Symbiodiniaceae are common across marine invertebrates. Reef-building corals offer a unique example of cellular dysfunction that leads a dysbiosis (coral bleaching) that is visible to the naked eye and occurs at an ecosystem scale. Due to their obligate symbioses, understanding the molecular underpinnings that sustain this relationship in reef-building corals is challenging, as any aposymbiotic state is inherently coupled with severe physiological stress. Here, we use the sub-tropical, facultatively symbiotic and calcifying coral Oculina arbuscula, to investigate gene expression differences between aposymbiotic and symbiotic host tissues from branches of the same colonies. This framework allows us to unravel the molecular networks that regulate symbiosis in the absence of a stress response. We find that many of the previously implicated pathways identified in studies using bleached corals, aposymbiotic larvae, or model systems (i.e. Aiptasia), are also differentially regulated between aposymbiotic and symbiotic tissues of O. arbuscula. We then take a comparative approach to investigate symbiosis pathways across other marine taxa. Our results point to key processes such as cell adhesion, control of cell division, and immune response, which appear necessary for the maintenance of symbiosis across organisms. Understanding the mechanisms that sustain a healthy symbiosis with Symbiodiniaceae is of urgent importance given the vulnerability of these partnerships to changing environmental conditions and their role in the continued functioning of key marine ecosystems such as coral reefs.
