Stanford Reseachers Identify Coral Gene Associated with Heat Tolerance

Numerous studies have confirmed how coral reefs indicate how climate change has worsened in recent years due to bleaching or how they respond to stressors. In a recent study, scientists identified a specific gene associated with heat tolerance.

Stanford University researchers used the CRISPR-Cas9, a gene-editing tool, to study the coral species Acropora millepora, or the anemone Aiptasia, in the Great Barrier Reef. The findings were recently published in the journal Proceedings of the National Academy of Sciences.

Coral Bleaching

Corals are highly sensitive to changes in water temperature. As a response to warmer waters, corals expel algae that reside in their tissue and turn white which is known as bleaching.

Although corals can survive bleaching events, it makes them vulnerable to disease and death. Another study revealed that seemingly healthy coral could be susceptible to disease when warmer temperatures stress out corals and affect its microbiome. As a result, viruses take advantage of weak corals which could also trigger bleaching.

Up to one-fourth of the Great Barrier Reef has experienced severe bleaching and about 35% of the reef underwent moderate bleaching. Earlier in April, the reef experienced its third mass bleaching event since 2015 which was anticipated to occur in 2050.

Gene Associated With Heat Tolerance

During the new study, the team identified two main clusters of hundreds of genes. Cluster one included genes associated with innate immunity and apoptosis (programmed cell death) while cluster two included genes responsible for protein folding and transcription.

Line Bay from the Australian Institue of Marine Science explained that examining the genetic traits of how corals tolerate heat is not only important in terms of global warming. Understanding coral resilience will also help researchers assess "opportunities and risks of novel management tools such as selective breeding and movement of corals among reefs."

A key gene to coral heat tolerance is the Heat Shock Transcription Factor 1 gene (HSF1). Using the CRISPR-Cas9 system, the team discovered "the function of a key gene that influences the ability of coral to survive heat," by silencing the HSF1 gene expression in coral larvae, explained Philip Cleves.

The modified larvae remained healthy and stable at 80°F but perished at 93°F. On the other hand, unedited coral larvae persisted as the water temperature got warmer. Dimitri Perrin explained how the results confirmed that HSF1 plays a key role when corals are coping with warmer temperatures. Moreover, gene editing may be a useful tool in preserving and restoring coral reefs.

According to the United Nations on the Economics of Ecosystems and Biodiversity, over 270 million people around the world depend on coral reefs for their livelihood and source of food. The National Oceanic and Atmospheric Administration also revealed that reefs take decades to recover, but recent trends in global warming are causing mass bleaching at alarming rates and could result in irreversible damage.

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