Genome editing experiments show the gene for heat tolerance in corals.

Using the CRISPR-Cas9 technique to precisely modify the genome of corals on the Great Barrier Reef, the scientists identified a critical gene for heat tolerance in Acropora millepora.

The discovery, which was detailed in the journal PNAS on Monday, could help protect coral reef ecosystems from the effects of climate change.

“We developed an improved CRISPR-Cas9 method that allowed us to test gene function in corals for the first time,” study lead author Philip Cleves said in a press release.

“As a proof of concept, we used CRISPR-Cas9 genome editing to understand the function of a key gene that affects corals’ ability to survive heat,” said Cleves, senior researcher in the Carnegie Institute’s Department of Embryology. for Science.

Coral reefs around the world have been degraded by bleaching processes triggered by longer, more frequent and more intense heat waves in the ocean. But not all coral species suffered equally: some species showed greater resistance than others.

“Understanding the genetic characteristics of coral heat tolerance is the key to understanding not only the natural response of corals to climate change, but also to assessing the benefits, opportunities and risks of new management tools such as selective breeding and coral movement between coral reefs, ”said co-author Line Bay, a researcher at the Australian Institute of Marine Sciences.

Previous gene editing technologies were too imprecise to isolate and manipulate individual genes and to perform the kind of experiments that the latest study made possible.

However, the CRISPR-Cas9 system works like a pair of surgical scissors, capable of silencing certain genes or replacing them with alternative DNA fragments.

For the new study, the scientists silenced the HSF1 gene, the gene for the heat shock transcription factor 1, which plays an important role in the heat tolerance of other organisms, previous studies have shown.

The modified coral larvae proved healthy when the water temperature in the laboratory remained stable at 27 degrees Celsius. However, when the researchers heated the pools to 34 degrees Celsius, the coral larvae died.

In contrast, the untreated coral larvae remained despite the rising water temperature.

“By removing the gene and then exposing the coral larvae to heat stress, we were able to show that the modified coral larvae died, while the unmodified larvae remained unharmed due to the temperature increase,” he said. co-author Dimitri Perrin.

“This finding demonstrates the key role HSF1 plays in helping corals cope with rising temperatures,” said Perrin, a data scientist at the University of Queensland in Australia.

Researchers suspect that the results provided by CRISPR-Cas9 – and even the editing tool itself – could prove useful for coral reef conservation and restoration.