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ABSTRACT Coral reefs are increasingly threatened by disease outbreaks, yet little is known about the genetic mechanisms underlying disease resistance. Since the 1970s, White Band Disease (WBD) has decimated the Caribbean staghorn coralAcropora cervicornis. However, 15% or more of individuals are highly disease‐resistant, and the genes controlling the production of Argonaut proteins, involved in microRNA (miRNA) post‐transcriptional gene silencing, are up‐regulated in WBD‐resistant corals. This suggests that miRNAs may be key regulators of coral immunity. In this study, we conducted an in situ disease transmission experiment with five healthy‐exposed control tanks and five WBD‐exposed tanks, each containing 50A. cervicornisgenotypes, sampled over 7 days and then sequenced miRNAs from 12 replicate genotypes, including 12 WBD‐exposed and 12 healthy‐exposed control fragments from two time points. We identified 67bona fidemiRNAs inA. cervicornis, 3 of which are differentially expressed in disease‐resistant corals. We performed a phylogenetic comparison of miRNAs across cnidarians and found greater conservation of miRNAs in more closely related taxa, including all three differentially expressed miRNAs being conserved in more than oneAcroporacoral. One of the three miRNAs has putative genomic targets involved in the cnidarian innate immunity. In addition, community detection coupled with over‐representation analysis of our miRNA–messenger RNA (mRNA) target network found two key uniqueA. cervicornismiRNAs regulating multiple important immune‐related pathways such as Toll‐like receptor pathway, endocytosis, and apoptosis. These findings highlight how multiple miRNAs may help the coral host maintain immune homeostasis in the presence of environmental stress including disease.
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Coral Venom and Toxins as Protection Against Crown‐of‐Thorns Sea Star Attack
ABSTRACT Crown‐of‐thorns sea star (CoTS) outbreaks are a main cause of hard coral cover decline across the Indo‐Pacific, posing a major threat to the resilience of coral reefs. However, the drivers underlying CoTS feeding on preferred (e.g.,Acroporaspecies) versus non‐preferred (e.g.,Poritesspecies) are poorly understood. We hypothesised that coral venom may influence CoTS prey preferences. To investigate this hypothesis, we compared the coral venom toxin families across the genomes of preferred (A. digitifera,A. hyacinthus,A. milleporaandA. tenuis) and non‐preferred (P. australiensis,P. compressa,P. luteaandP. rus) prey species of CoTS. We also included one species from each genus inhabiting the Caribbean, where CoTS are absent (A. cervicornisandP. astreoides), to broaden our identification of venom constituents shared within each genus and investigate geographic differences. We collected known cnidarian toxins, and along with the cnidarian Tox‐Prot database, used these to identify putative toxins and investigate their phylogeny. The most abundant toxins across all coral species included neurotoxins (kunitz‐type and SCRiPS) and pore‐forming toxins (actinoporins and MAC‐PFs). We found genera‐specific differences with jellyfish toxins (CFXs) only present inPoritesspecies. Similarly, onlyAcroporaspecies harboured pore‐forming toxins with the aerolysin domain. Two toxin homologues only present in Indo‐Pacific corals (CFX and MAC‐PF homologues) showed evidence of positive selection, suggesting their evolution is shaped by environmental pressures, including exposure to CoTS. These findings provide a foundation for future studies of scleractinian venoms, which have direct applications to assessing reef coral's susceptibility to future CoTS outbreaks and active reef management.
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- Award ID(s):
- 2348674
- PAR ID:
- 10668075
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 35
- Issue:
- 1
- ISSN:
- 0962-1083
- Subject(s) / Keyword(s):
- Acropora | crown-of-thorns sea star | neurotoxins | pore-forming toxins | Porites | venom
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/mec.70202
