Dual RNA‐sequencing analyses of a coral and its native symbiont during the establishment of symbiosis

Abstract

Despite the ecological significance of the mutualistic relationship between Symbiodiniaceae and reef-building corals, the molecular interactions during establishment of this relationship are not well understood. This is particularly true of the transcriptional changes that occur in the symbiont. In the current study, a dual RNAsequencing approach was used to better understand transcriptional changes on both sides of the coral-symbiont interaction during the colonization of Acropora tenuis by a compatible Symbiodiniaceae strain (Cladocopium goreaui; ITS2 type C1). Comparison of transcript levels of the in hospite symbiont 3, 12, 48 and 72 hr after exposure to those of the same strain in culture revealed that extensive and generalized down-regulation of symbiont gene expression occurred during the infection process. Included in this "symbiosis-derived transcriptional repression" were a range of stress response and immune-related genes. In contrast, a suite of symbiont genes implicated in metabolism was upregulated in the symbiotic state. The coral data support the hypothesis that immune-suppression and arrest of phagosome maturation play important roles during the establishment of compatible symbioses, and additionally imply the involvement of some SCRiP family members in the colonization process. Consistent with previous ecological studies, the transcriptomic data suggest that active translocation of metabolites to the host may begin early in the colonization process, and thus that the mutualistic relationship can be established at the larval stage. This dual RNA-sequencing study provides insights into the transcriptomic remodelling that occurs in C. goreaui during transition to a symbiotic lifestyle and the novel coral genes implicated in symbiosis.

Cnidarian Pattern Recognition Receptor Repertoires Reflect Both Phylogeny and Life History Traits

“…A recent study indicates that in E. daiphana , a symbiotic anemone, microalgae are taken into the cell largely indiscriminately and the decision to retain these microalgae as symbionts or expel them likely occurs intracellularly ( 114 ). As intracellular PRRs, NLRs are great candidates for modulating interactions between the algal symbionts and the immune system of their cnidarian hosts during the establishment of symbiosis, a hypothesis with some support from transcriptomic studies ( 115 ).…”

Transcriptome Analysis of Durusdinium Associated with the Transition from Free-Living to Symbiotic

“…Furthermore, a large number of ribosomal and chaperone proteins were detected among the downregulated DEGs, suggesting that some translational and protein-folding functions were inactivated following endosymbiosis establishment. Decreased expression of the chaperone gene has also been reported in the genera Symbiodinium and Cladocopium [ 11 ], and may represent a typical response to coral endosymbiosis establishment. It should be noted, however, that some of the DEGs detected include genes that were altered due to environmental differences between the two states.…”

“…In coral cells, algae are present in host-derived acidified vesicles that have carbon-concentrating mechanisms and activate photosynthetic capacity [ 7 ]. A recent transcriptome analysis found that dinoflagellate genes involved in molecular chaperoning as well as sugar and ammonia transportation were suppressed during the establishment of endosymbiosis with Aiptasia and coral planula larvae [ 10 , 11 ]. Gene expression analyses of actin, Ca 2+ ATPase, and H + APTase in Symbiodiniaceae also revealed that their expression patterns differed considerably between the non-symbiotic and symbiotic states [ 12 , 13 ].…”

“…However, despite these recent advances, many aspects of the changes dinoflagellate undergo during coral endosymbiosis establishment remain unclear. Previous studies have established a model endosymbiosis system consisting of monoclonal alga and juvenile corals, and transcriptome data for these coral–alga complexes have been published, with a focus on coral gene expression [ 11 , 14 , 15 , 16 ]. By contrast, the gene expression levels of dinoflagellate during coral endosymbiosis have not been investigated due to a lack of transcriptome data for the non-symbiotic state.…”

Host-Parasite Interaction of Atlantic salmon (Salmo salar) and the Ectoparasite Neoparamoeba perurans in Amoebic Gill Disease

“…However, by contrasting the lesion with the culture condition where there are no host signals, this improves the reliability of identification of N. perurans genes in the hostparasite interaction. The same method was employed by Mohamed et al (36) in their dual RNA-seq study of a coral (Acropora tenuis) and its symbiont (Cladocopium goreaui) during the establishment of symbiosis.…”