Engineering Strategies to Decode and Enhance the Genomes of Coral Symbionts.

Elevated sea surface temperatures from a severe and prolonged El Niño event (2014-2016) fueled by climate change have resulted in mass coral bleaching (loss of dinoflagellate photosymbionts, spp., from coral tissues) and subsequent coral mortality, devastating reefs worldwide. Genetic variation within and between species strongly influences the bleaching tolerance of corals, thus recent papers have called for genetic engineering of to elucidate the genetic basis of bleaching-relevant traits. However, while has been intensively studied for over 50 years, genetic transformation of has seen little success likely due to the large evolutionary divergence between and other model eukaryotes rendering standard transformation systems incompatible. Here, we integrate the growing wealth of next-generation sequencing data to design tailored genetic engineering strategies. Specifically, we develop a testable expression construct model that incorporates endogenous promoters, terminators, and genes of interest, as well as an internal ribosomal entry site from a virus. Furthermore, we assess the potential for CRISPR/Cas9 genome editing through new analyses of the three currently available genomes. Finally, we discuss how genetic engineering could be applied to enhance the stress tolerance of , and in turn, coral reefs.