Project description:Reef-building corals live in a mutualistic relationship with photosynthetic algae (family Symbiodiniaceae) that usually provide the bulk of the energy required by the coral host. This relationship is very sensitive to temperature stress, with as little as 1°C increase above mean in sea surface temperatures (SSTs) often leading to the collapse of the association. The meta-stability of these associations has led to interest in the potential of more stress tolerant algae to supplement or substitute for the normal Symbiodiniaceae mutualists. In this respect, the apicomplexan-like microalga Chromera is of particular interest as it is considerably more temperature tolerant than are most members of the Symbiodiniaceae. Here we generated a de novo transcriptome for a Chromera strain isolated from a GBR coral (“GBR Chromera”) and compared to those of the reference strain of Chromera (“Sydney Chromera”), and to those of Symbiodiniaceae algae (Fugacium, Cladocopium and Breviolum), as well as the apicomplexan parasite, Plasmodium falciparum. By contrast with the Symbiodiniaceae, the two Chromera strains had a high level of sequence similarity evident by very low levels of divergence in orthologous genes. Although surveys of specific KEGG categories provided few general criteria by which true coral mutualists might be identified, they provide a molecular rationalization for the near ubiquitous association of Cladocopium strains with Indo-Pacific reef corals in general and with Acropora spp. in particular. In addition, HSP20 genes may underlie the higher thermal tolerance shown by Chromera compared to Symbiodiniaceae
Project description:Heat-evolved Symbiodiniaceae can improve the physiological performances of their coral host under heat stress, but their gene expression responses to heat remained unknown. We explore here the transcriptomic basis of differential thermal stress responses between in hospite wild-type and heat-evolved Cladocopium proliferum strains and their coral host Platygyra daedealea.
Project description:Urea can serve as nitrogen source for coral holobionts and plays a cruscial role in coral calcification, although the degradation of urea by coral symbionts is not fully understood. In this study, we investigated the urea utilized pathway and the responses of the Symbiodiniaceae family to urea under high temperature conditions. Genome screening revealed that all Symbiodiniaceae species contain the urease (URE) and DUR2 subunit of urea amidolyase (UAD) system. However, only three speciesCladocopium goreaui, Cladopium c92, and Symbiodinium pilosum possess a complete UAD system, including both DUR1 and DUR2. Phylogentic analyses revealed that the UAD system in Symbiodiniaceae clusters more closely with symbiotic bacteria, indicating that horizontal gene transfer of UAD system has occured in coral symbionts. Physiology analysis showed that the symbiodiniacean species Cladocopium goreaui, which containing both URE and UAD, grew better under urea than ammonium conditions, as indicated by higher maximum specific growth rates. Furthermore, most genes of Symbiodiniaceae involved in urea utilization appeared to be stable under various conditions such as heat stress (HS), low light density, and nitrogen deficiency, wheras in ammonium and nitrate transporters were significantly regulated. These relatively stable molecular regulatory properties support sustained urea absorption by Symbiodiniaceae, as evidenced by an increase in δ15N2-urea absorption and the decreases in δ5N-NO3-, and δ15N-NH4+ from cultural environment to Symbiodiniaceae under HS conditions. Token together, this study reveals two distinct urea utilization systems in coral ecosystem and highlights the importance of the urea cycle in coral symbionts when facing fluctuating nitrogen environment in future warming ocean.
2024-09-27 | PXD056312 | Pride
Project description:Symbiodiniaceae ITS2 diversity of coral
Project description:Coral reefs are declining globally. Temperature anomalies disrupt coral-algal symbioses at the molecular level, causing bleaching and mortality events. In terrestrial mutualisms, diversity in pairings of host and symbiont individuals (genotypes) results in ecologically and evolutionarily relevant stress response differences. The extent to which such intraspecific diversity provides functional variation in coral-algal systems is unknown. Here we assessed functional diversity among unique pairings of coral and algal individuals (holobionts). We targeted six genetically distinct Acropora palmata coral colonies that all associated with a single, clonal Symbiodinium ‘fitti’ strain in a natural common garden. No other species of algae or other strains of S. ‘fitti’ could be detected in host tissues. When colony branches were experimentally exposed to cold stress, host genotype influenced the photochemical efficiency of the symbiont strain, buffering the stress response to varying degrees. Gene expression differences among host individuals with buffered vs. non-buffered symbiont responses included biochemical pathways that mediate iron availability and oxygen stress signaling—critical components of molecular interactions with photosynthetic symbionts. Spawning patterns among hosts reflected symbiont performance differences under stress. These data are some of the first to indicate that genetic interactions below the species level affect coral holobiont performance. Intraspecific diversity serves as an important but overlooked source of physiological variation in this system, contributing raw material available to natural selection. Note: in the final publication, only ambient and cold treatments are discussed, but there was an additional hot treatment for each genotype at 34C. Most colonies expired after 6 hours, so PAM data could not be collected. The microarray data from 3.5 hours are included here.
2015-10-01 | GSE50926 | GEO
Project description:Coral endosymbiotic Symbiodiniaceae ITS2 diversity in the Huangyan Island
Project description:Transcriptional responses to heat stress were assayed in early life-history stages of 11 crosses between and amongst Acropora tenuis colonies originating from reefs along the Great Barrier Reef. We identified a single nucleotide polymorphism outlier (Fst=0.89) between populations in the unannotated gene Acropora25324, which exhibited constitutively higher gene expression in populations with dams originating from Curd reef, a far north, warm adapted inshore reef, suggesting an important role of this gene in adaptation to warmer environments. Further, juveniles exposed to heat and in symbiosis with heat-evolved Symbiodiniaceae displayed intermediate transcriptional responses between its progenitor taxa (Cladocopium goreaui) and the more stress tolerant Durusdinium trenchii, indicating that the development of heat tolerance acquisition is potentially a conserved evolutionary process in Symbiodiniaceae. These findings reveal the underlying mechanisms, and for the first time, their relative contribution, of coral responses to climate change and provide a foundation for optimizing conservation methods like assistant gene flow.
2022-07-08 | GSE176051 | GEO
Project description:Coral fungs and Symbiodiniaceae