Dying Great Barrier Reef Forces Scientists to Genetically Engineer Coral

The Great Barrier Reef is dying. Global ocean temperature rise has bleached and killed coral reefs all over the world, but the Great Barrier Reef has been particularly hard, losing 29 percent of its reefs in 2016 alone. As the old saying goes, desperate times call for desperate measures, and the dire plight of the Great Barrier Reef has forced scientists to look to one radical solution to save them: genetic engineering.

In a paper published Monday in the journal Proceedings of the National Academy of Sciences, researchers report that they’ve used the cheap and precise CRISPR/Cas9 gene editing technology to induce specific mutations in cells of Acropora millepora, a species of coral that’s highly abundant in the Great Barrier Reef. Coral is a living organism that reproduces by laying eggs, so the scientists hypothesized that introducing positive mutations into the eggs could confer new, potentially survival-boosting characteristics on the species. In the study, the researchers succeeded in introducing specific mutations to coral in tests performed in a lab to prevent accidental genetic changes in wild coral. By doing so, they proved the concept that scientists can alter the genetic code of corals in a way that could persist through generations.

In this study, the scientists used CRISPR/Cas9 to knock out three genes in fertilized A. millepora eggs: one that encodes for a green fluorescent protein, one that encodes for a red fluorescent protein, and one that encodes for fibroblast growth factor (FGF), a protein associated with coral colonization. While the FGF mutation was meant to alter the way the coral grows, the fluorescent protein mutations were simply meant to provide visual proof that the knockout worked — those with the mutations, in theory, would no longer glow red and green. The scientists were able to confirm that these mutations were incorporated into the genome, but it turns out that the coral genome encodes for these proteins at multiple sites. As a result, the coral still glowed, but not as brightly, and only some stopped making FGF. So, the experiment didn’t exactly produce the results the researchers expected, but it did help them learn about CRISPR’s ability to alter multiple similar genes.

“There is an urgent need to develop the genetic methods that will allow rigorous testing of hypotheses about gene and pathway function in various aspects of coral biology,” write the authors. “The powerful CRISPR/ Cas9 approach should greatly facilitate such efforts, and we report here encouraging results in this direction.” The study’s authors report that the mutations they induced lasted through several cell cycles. This isn’t the population-level change that would save the reefs, but it’s a start. And though this research simply set out to prove this concept, another recent study suggests a powerful direction researchers could take CRISPR/Cas9 in coral.

A paper published on April 19 showed that corals in the Great Barrier Reef could be evolving to withstand warmer waters. Scientists modeled the migration rates of genetic alleles associated with corals that tolerate warmer waters — waters that would normally bleach and kill coral. But they also found that these mutations could be too slow or too sensitive to save the reefs.

But that assumes natural levels of mutation. What if scientists sped up the process by employing CRISPR/Cas9 to help coral mutate heat-tolerant alleles? This latest paper suggests that, while that solution might not be possible right now, it’s plausible in the near future.