Multi-‘omic analysis of stony coral tissue loss disease resistance in restoration genotypes of Orbicella faveolata

There is a need for innovative research into the resistance and susceptibility of corals to stony coral tissue loss disease (SCTLD), particularly at the molecular level, to support conservation of impacted coral reef populations as well as active restoration of degraded populations. Here, we investigated SCTLD resistance in Mote Marine Laboratory’s nursery genotypes of the endangered coral Orbicella faveolata through disease transmission experiments, while developing quantitative metrics to assess susceptibility, genetic structure, and microbial bioindicators of disease resistance. By conducting disease challenges across 170 putative genotypes of O. faveolata in the largest ex-situ coral disease transmission experiment to date, we identified five susceptibility categories that accurately predict disease outcomes in field settings. We also developed the most complete genome/transcriptome assemblies of any Caribbean coral species to date, and incorporated high-resolution genotyping of these experimental genotypes and all additional nursery O. faveolata, providing critical information to maximize genetic diversity in propagation and outplanting efforts. While we did not find a genetic basis for SCTLD resistance in this species, we identified microbial taxa in resistant genotypes with a co-evolved relationship to the coral host. These taxa are a priority for development as bioindicators of SCTLD resistance in order to screen additional coral populations, as well as in further investigation in their role during SCTLD pathogenesis. These ‘omics datasets have been made available as public resources through the National Center for Biotechnology Information (NCBI) and the Disturbance Advisory Committee (DAC) to improve future ‘omics investigations into coral resilience. The outcomes of this project have been incorporated into an ongoing coral disease response effort which seeks to improve understanding about the scale and severity of the coral disease outbreak on Florida’s Coral Reef, identify primary and secondary causes, identify management actions to remediate disease impacts, restore affected resources, and ultimately prevent future outbreaks.