Antimicrobial and stress responses to increased temperature and bacterial pathogen challenge in the holobiont of a reef-building coral

van de Water, Jeroen A.J.M., Chaib de Mares, Maryam, Dixon, Groves B., Raina, Jean-Baptiste, Willis, Bette L., Bourne, David G., and van Oppen, Madeleine J.H. (2018) Antimicrobial and stress responses to increased temperature and bacterial pathogen challenge in the holobiont of a reef-building coral. Molecular Ecology, 27 (4). pp. 1065-1080.

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Abstract

Global increases in coral disease prevalence have been linked to ocean warming through changes in coral-associated bacterial communities, pathogen virulence and immune system function. However, the interactive effects of temperature and pathogens on the coral holobiont are poorly understood. Here, we assessed three compartments of the holobiont (host, Symbiodinium and bacterial community) of the coral Montipora aequituberculata challenged with the pathogen Vibrio coralliilyticus and the commensal bacterium Oceanospirillales sp. under ambient (27°C) and elevated (29.5 and 32°C) seawater temperatures. Few visual signs of bleaching and disease development were apparent in any of the treatments, but responses were detected in the holobiont compartments. V. coralliilyticus acted synergistically and negatively impacted the photochemical efficiency of Symbiodinium at 32°C, while Oceanospirillales had no significant effect on photosynthetic efficiency. The coral, however, exhibited a minor response to the bacterial challenges, with the response towards V. coralliilyticus being significantly more pronounced, and involving the prophenoloxidase-activating system and multiple immune system-related genes. Elevated seawater temperatures did not induce shifts in the coral-associated bacterial community, but caused significant gene expression modulation in both Symbiodinium and the coral host. While Symbiodinium exhibited an antiviral response and upregulated stress response genes, M. aequituberculata showed regulation of genes involved in stress and innate immune response processes, including immune and cytokine receptor signalling, the complement system, immune cell activation and phagocytosis, as well as molecular chaperones. These observations show that M. aequituberculata is capable of maintaining a stable bacterial community under elevated seawater temperatures and thereby contributes to preventing disease development.

Item ID: 52821
Item Type: Article (Research - C1)
ISSN: 1365-294X
Keywords: bacteria, climate change, coral, disease, holobiont, immune response, Oceanospirillales, Symbiodinium, symbiosis, Vibrio coralliilyticus
Funders: Australian Coral Reef Society, Australian Research Council (ARC), James Cook University, Australian Institute of Marine Science (AIMS)
Date Deposited: 08 Mar 2018 01:50
FoR Codes: 06 BIOLOGICAL SCIENCES > 0605 Microbiology > 060599 Microbiology not elsewhere classified @ 100%
SEO Codes: 96 ENVIRONMENT > 9699 Other Environment > 969999 Environment not elsewhere classified @ 100%
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