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.
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 and reef habitat Symbiodiniaceae
| PRJNA1157714 | ENA
Project description:Symbiodiniaceae ITS2 diversity of coral
Project description:Samples are from a screening experiment on 5 laboratory cultures of the coral endosymbiont: Symbiodiniaceae (Symbiodinium linuchae, Breviolum psygmophilum, Durusdinium trenchii, Effrenium voratum and Fugacium kawagutii). Samples are also from a thermal stress experiment (increased temperatures from 26 to 32 degrees C) carried out on Durusdinium trenchii and Cladocopium goreaui, two common coral endosymbionts on the Great Barrier Reef. All samples were collected on Markes Tenax TA thermal desorption tubes.
Lawson, C.A., Possell, M., Seymour, J.R., Raina, J.B. and Suggett, D.J., 2019. Coral endosymbionts (Symbiodiniaceae) emit species-specific volatilomes that shift when exposed to thermal stress. Scientific reports, 9(1), pp.1-11.
Project description:Background: The molecular machinery underpinning the establishment of this relationship is not well understood. This is especially true of the symbiont side, as previous attempts to understand the interaction between coral larvae and Symbiodiniaceae have focused nearly exclusively on the host Results: In the current study, we utilised dual RNA-seq approach to study both symbiont and coral transcriptomes during symbiosis establishment. The transcriptomic response of C. goreaui to the symbiotic state was complex, the most obvious feature of which was extensive and generalized downregulation of gene expression. Included in this “symbiosis-derived transcriptional repression” were a range of stress response and immune-related genes. In contrast, a range of genes implicated in metabolism were upregulated in the symbiotic state. Consistent with previous ecological studies, this transcriptomic response of C. goreaui suggests that active translocation of metabolites to the host may begin early in the colonization process, and thus that the mutualistic relationship is established at the larval stage. The coral data imply the involvement of some SCRiP family members in the colonisation process and support the hypothesis that immune-suppression and arrest of phagosome maturation play important roles during the establishment of compatible symbioses. Conclusions: This study provides novel insights into the transcriptomic remodelling that occurs in C. goreaui during transition to a symbiotic lifestyle, with important implications for understanding the establishment of symbiosis between corals and their dinoflagellate partners.
2020-08-13 | GSE145030 | GEO
Project description:Genetic Diversity Dataset of Coral Symbiodiniaceae
Project description:<p>As a well-known pseudo-persistent environmental pollutant, oxybenzone (BP-3) and its related organic ultraviolet (UV) filters have been verified to directly contribute to the increasing mortality rate of coral reefs. Previous studies have revealed the potential role of symbiotic Symbiodiniaceae in protecting corals from the toxic effects of UV filters. However, the detailed protection mechanism(s) have not been explained. Here, the impacts of BP-3 on the symbiotic Symbiodiniaceae <em>Cladocopium goreaui</em> were explored. <em>C. goreaui</em> cells exhibited distinct cell growth at different BP-3 doses, with increasing growth at the lower concentration (2 mg/L) and rapid death at a higher concentration (20 mg/L). Furthermore, <em>C. goreaui</em> cells showed a significant BP-3 uptake at the lower BP-3 concentration. BP-3 absorbing cells exhibited elevated photosynthetic efficiency, and decreased cellular carbon and nitrogen contents. Besides, the derivatives of BP-3 and aromatic amino acid metabolism highly responded to BP-3 absorption and biodegradation. Our physiological and metabolic results reveal that the symbiotic Symbiodiniaceae could resist the toxicity of a range of BP-3 through promoting cell division, photosynthesis and reprogramming amino acid metabolism. This study provides novel insights into the influences of organic UV filters to coral reef ecosystems, which urgently needs increasing attention and management.</p>