Metabolomic shifts associated with heat stress in coral holobionts

Abstract

Understanding the response of the coral holobiont to environmental change is crucial to inform conservation efforts. The most pressing problem is “coral bleaching,” usually precipitated by prolonged thermal stress. We used untargeted, polar metabolite profiling to investigate the physiological response of the coral species Montipora capitata and Pocillopora acuta to heat stress. Our goal was to identify diagnostic markers present early in the bleaching response. From the untargeted UHPLC-MS data, a variety of co-regulated dipeptides were found that have the highest differential accumulation in both species. The structures of four dipeptides were determined and showed differential accumulation in symbiotic and aposymbiotic (alga-free) populations of the sea anemone Aiptasia (Exaiptasia pallida), suggesting the deep evolutionary origins of these dipeptides and their involvement in symbiosis. These and other metabolites may be used as diagnostic markers for thermal stress in wild coral.

Species-Specific Variations in the Metabolomic Profiles of Acropora hyacinthus and Acropora millepora Mask Acute Temperature Stress Effects in Adult Coral Colonies

“…Running the experiment for slightly longer time periods (16 days to 5 weeks for example), would have likely resulted in more profound shifts in the metabolomic profiles of the corals. Our results would have then likely reflected studies such as Williams et al (2021), who illustrated changes in the metabolome of heat tolerant Montipora capitata and heat sensitive Pocillopora acuta. However, this latter study did not present generalized patterns in their metabolomics data (as presented in this study), instead choosing to focus on specific metabolomic features that accumulated during stress, making direct comparisons difficult.…”

“…Arguably, these shifts should be observable prior to any visual signs of ill health-therefore acting as an early warning tool or bioindicator of stress events. Despite the significant potential gains in organismic understanding offered by metabolome studies, metabolism research in corals has only recently gained traction (Sogin et al, 2014(Sogin et al, , 2016Farag et al, 2016;Quinn et al, 2016;Galtier d'Auriac et al, 2018;Hillyer et al, 2018;Lohr et al, 2019;Vohsen et al, 2019;Roach et al, 2020;Williams et al, 2021). That said, the Cnidarians as a group have been the focus of an extensive chemical industry based on marine products for decades (Kornprobst, 2014).…”

“…For example, as anti-microbials, anti-inflammatories and cytotoxins for cancer cell lines (Vohsen et al, 2019). As such, there is well-developed understanding of how certain metabolites (for example, sugars, lipids and mycosporinelike amino acids) are associated with particular responses in Cnidarian hosts (Hillyer et al, 2017a(Hillyer et al, , 2018Galtier d'Auriac et al, 2018;Roach et al, 2020;Williams et al, 2021). In contrast, the behavior of other metabolites such as steroids, isoprenoids, alkaloids, and sulfur containing compounds such as dimethylsulphoniopropionate (DMSP) and glycosaminoglycans and/or their breakdown products including acrylate, have been studied far less (Sogin et al, 2014;Yuyama et al, 2016;Westmoreland et al, 2017;Williams et al, 2021).…”

“…The understudied metabolites are undoubtedly important to corals as they have been linked with coral reproduction, growth, survival and maintenance of symbiotic status (Tarrant et al, 2003;Gordon and Leggat, 2010;Tapiolas et al, 2010;Sogin et al, 2014;Williams et al, 2021). The maintenance of symbiotic relationships with algae (Symbiodiniaceae) is particularly important for reef building corals.…”

“…Horizontal gene transfer can also facilitate rapid evolution within microbial strains and change metabolic functions, with the potential to subsequently also confer beneficial traits to their host (Webster and Reusch, 2017). The corals themselves also produce and mobilize other small compounds, including steroids, DMSP, betaines, and a diverse assemblage of lipids and mycosporine-like amino acids (Raina et al, 2013;Sogin et al, 2014;Westmoreland et al, 2017;Ngugi et al, 2020;Williams et al, 2021).…”