ORCC: The Role of Betaine Lipid Biochemistry in Coral Thermal Tolerance

Reef building corals are a symbiotic association between a coral animal and its many microbial associates, including algae. Temperature is threatening corals worldwide by causing a phenomenon called coral bleaching, which is a breakdown of the symbiosis that can lead to death during thermal stress. However, some corals show an inherent resistance to bleaching. This project will aim to understand how molecules from symbiotic algae contribute to coral thermal resistance. Preliminary work has shown that thermally resistant corals contain unique lipids that are not present in those susceptible to bleaching. This project will explore the role of these lipids in the response of corals to thermal stress. Methods, including DNA and RNA sequencing and mass spectrometry, will be used to characterize thousands of molecules from corals during thermal stress experiments in aquaria and on live reefs in Hawai’i. The ultimate goal is to understand how these lipids contribute to bleaching resistance and to use these methods to identify thermally resistant stock for restoring threatened Hawaiian reefs. Corals will be selectively bred based on this data and monitored for bleaching years after the project’s completion to determine whether these corals remain resistant to thermal stress associated with climate change. Integrated into the project are programs to involve students. Collectively, this project will have broader impacts on coral reef restoration while synergistically introducing students to the exciting field of marine biology. Reef building corals are a symbiotic association of a Cnidarian host, algal symbionts, and myriad microorganisms. Thermal stress is threatening reefs worldwide due to coral bleaching, which is a breakdown of this symbiosis that can lead to coral death. However, some corals show an inherent resistance to thermal stress, driven by interactions among its symbiotic constituents. This collaborative project will aim to understand how unique lipids from symbiotic algae and other biochemicals contribute to coral thermal resistance. Preliminary data has shown that resistant corals contain abundant, saturated ‘betaine lipids’, specifically the DGCC class, which are a novel group of phosphate-free membrane lipids unique to unicellular algae. This project will use advanced metabolomics and mass spectrometry methods to characterize the biochemical relationships between symbiotic algae and their coral hosts and characterize the biosynthetic pathway for the production of the saturated betaine lipids. Resistant coral stock will be selectively bred based on their lipid profiles to improve restoration efforts. The ultimate aim is to understand the dynamism and/or plasticity of corals during thermal stress and provide a biochemical understanding of how corals will respond to dynamic environments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.