As climate change increases stress on coral and their symbionts, extinction is on the horizon. Reefs are given shorter and shorter intervals to recover naturally which can be seen most easily as the effect of coral bleaching. The coral bleaching effect is a result of symbiotic dinoflagellate expulsion from the main coral body. The dinoflagellates provide essential nutrient processing to coral bodies, such as photosynthesis, so their expulsion causes the coral to die.
An article about how Symbiodiniaceae, a genus of dinoflagellate, meets the challenges of life during coral bleaching explains the specific impacts climate change has on the Symbiodinium genome. Symbiodiniaceae first alters at transcriptomic levels potentially mediated by second messenger systems, followed by proteomics and metabolic reprogramming. By pinpointing specific changes and differences among the 7 Symbiodinium clades, identification of stress-specific or stress-independent genes could be utilized for trait improvement using genetic engineering.
Hope is found in research that is being conducted on the implementation of Type I RuBisCO as opposed to the Type II RuBisCO currently found in Symbiodiniaceae. The Type I RuBisCO found in cyanobacterium provides a more heat-resistant form which will help maintain the rate of the Calvin-Benson Cycle during photosynthesis. Increasing heat resistance will help maintain the integrity of the symbiotic relationship.
Although genetic engineering is frightening in the sense that it can induce a monoculture, at the rate the planet is heating up, coral reefs are already vulnerable. It is paramount for each variety of genetically engineered coral to maintain a level of genetic diversity to lower its vulnerability to environmental factors not mitigated by targeted genetic alterations. I do not believe that any one genetically modified coral-symbiont combination should be the stopping point. It is only a good first step in preserving biodiversity, so one of the most genetically diverse ecosystems does not cease to exist in the coming years.
What to read next: Thermal tolerance of the hermatypic coral Acropora tenuis elucidated by RGB analysis and expression of heat shock proteins in coral and symbiotic dinoflagellates