Nature of coral-Chromera interaction revealed: photosynthetic symbionts are not always beneficial to corals

An international team of scientists, led by Prof David Miller and Dr Amin Mohamed, has found that the coral-associated alga Chromera, despite being a near-relative of Symbiodinium (the photosynthetic symbiont essential for the survival of reef-building corals), is not beneficial to corals. Previously it had been assumed that Chromera was an alternative coral photosymbiont that was more tolerant of heat stress than is Symbiodinium. The new study, published in Nature’s ISME Journal, comprehensively debunks the myth that Chromera is beneficial to corals. Rather than being greeted as a friend, corals mount a hostile response when exposed to Chromera.

To better understand the coral-Chromera association, the researchers investigated the response of every gene in the coral genome from the moment the juvenile coral first interacts with Chromera. The team compared this with the typical response of a coral larva to the known ally, Symbiodinium sp, and saw very different responses from those typical for beneficial types of Symbiodinium.

Read full paper here.