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Gene expression of corals in response to macroalgal competitors.

Shearer TL, Snell TW, Hay ME - PLoS ONE (2014)

Bottom Line: Genes of coral hosts and of their associated Symbiodinium also responded in species-specific and time-specific ways to each macroalga.Changes in number and expression intensity of affected genes were greater after 6 h compared to 48 h of contact and were greater following contact with Chlorodesmis fastigiata and Amphiroa crassa than following contact with Galaxaura filamentosa or Turbinaria conoides.Activation of the immune response by corals that better resist algal competition is consistent with the hypothesis that some macroalgal effects on corals may be mediated by microbial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Georgia Institute of Technology, School of Biology, 310 Ferst Dr., Atlanta, GA, 30332, United States of America.

ABSTRACT
As corals decline and macroalgae proliferate on coral reefs, coral-macroalgal competition becomes more frequent and ecologically important. Whether corals are damaged by these interactions depends on susceptibility of the coral and traits of macroalgal competitors. Investigating changes in gene expression of corals and their intracellular symbiotic algae, Symbiodinium, in response to contact with different macroalgae provides insight into the biological processes and cellular pathways affected by competition with macroalgae. We evaluated the gene expression profiles of coral and Symbiodinium genes from two confamilial corals, Acropora millepora and Montipora digitata, after 6 h and 48 h of contact with four common macroalgae that differ in their allelopathic potency to corals. Contacts with macroalgae affected different biological pathways in the more susceptible (A. millepora) versus the more resistant (M. digitata) coral. Genes of coral hosts and of their associated Symbiodinium also responded in species-specific and time-specific ways to each macroalga. Changes in number and expression intensity of affected genes were greater after 6 h compared to 48 h of contact and were greater following contact with Chlorodesmis fastigiata and Amphiroa crassa than following contact with Galaxaura filamentosa or Turbinaria conoides. We documented a divergence in transcriptional responses between two confamilial corals and their associated Symbiodinium, as well as a diversity of dynamic responses within each coral species with respect to the species of macroalgal competitor and the duration of exposure to that competitor. These responses included early initiation of immune processes by Montipora, which is more resistant to damage after long-term macroalgal contact. Activation of the immune response by corals that better resist algal competition is consistent with the hypothesis that some macroalgal effects on corals may be mediated by microbial pathogens.

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Mean gene expression (spot intensity) of all differentially expressed coral and Symbiodinium genes (combined) grouped by macroalgal treatment (ANOVA; P = 0.0003).Letters indicate significant groupings by Tukey-Kramer HSD post-hoc test.
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pone-0114525-g005: Mean gene expression (spot intensity) of all differentially expressed coral and Symbiodinium genes (combined) grouped by macroalgal treatment (ANOVA; P = 0.0003).Letters indicate significant groupings by Tukey-Kramer HSD post-hoc test.

Mentions: A. millepora and M. digitata coral and associated Symbiodinium displayed diverse alterations in gene expression in response to different macroalgal species (S5 Table). Exposure to Amphiroa crassa and C. fastigiata elicited significantly higher levels of gene expression (both coral species combined) than did exposure to Galaxaura filamentosa and Turbinaria conoides (Fig. 5; ANOVA, P = 0.0003). A. crassa and C. fastigiata treatments also shared the greatest number of affected genes across all treatments (19.1±4.6); however, most genes were differentially expressed in response to specific macroalgal species (Fig. 6), and not indicative of a general response to all macroalgae (e.g., of the 71 DEGs in Acropora following 6 h of contact with Amphiroa, 76% were unique to contact with Amphiroa as opposed to the other macroalgae (Fig. 6 upper left).


Gene expression of corals in response to macroalgal competitors.

Shearer TL, Snell TW, Hay ME - PLoS ONE (2014)

Mean gene expression (spot intensity) of all differentially expressed coral and Symbiodinium genes (combined) grouped by macroalgal treatment (ANOVA; P = 0.0003).Letters indicate significant groupings by Tukey-Kramer HSD post-hoc test.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264762&req=5

pone-0114525-g005: Mean gene expression (spot intensity) of all differentially expressed coral and Symbiodinium genes (combined) grouped by macroalgal treatment (ANOVA; P = 0.0003).Letters indicate significant groupings by Tukey-Kramer HSD post-hoc test.
Mentions: A. millepora and M. digitata coral and associated Symbiodinium displayed diverse alterations in gene expression in response to different macroalgal species (S5 Table). Exposure to Amphiroa crassa and C. fastigiata elicited significantly higher levels of gene expression (both coral species combined) than did exposure to Galaxaura filamentosa and Turbinaria conoides (Fig. 5; ANOVA, P = 0.0003). A. crassa and C. fastigiata treatments also shared the greatest number of affected genes across all treatments (19.1±4.6); however, most genes were differentially expressed in response to specific macroalgal species (Fig. 6), and not indicative of a general response to all macroalgae (e.g., of the 71 DEGs in Acropora following 6 h of contact with Amphiroa, 76% were unique to contact with Amphiroa as opposed to the other macroalgae (Fig. 6 upper left).

Bottom Line: Genes of coral hosts and of their associated Symbiodinium also responded in species-specific and time-specific ways to each macroalga.Changes in number and expression intensity of affected genes were greater after 6 h compared to 48 h of contact and were greater following contact with Chlorodesmis fastigiata and Amphiroa crassa than following contact with Galaxaura filamentosa or Turbinaria conoides.Activation of the immune response by corals that better resist algal competition is consistent with the hypothesis that some macroalgal effects on corals may be mediated by microbial pathogens.

View Article: PubMed Central - PubMed

Affiliation: Georgia Institute of Technology, School of Biology, 310 Ferst Dr., Atlanta, GA, 30332, United States of America.

ABSTRACT
As corals decline and macroalgae proliferate on coral reefs, coral-macroalgal competition becomes more frequent and ecologically important. Whether corals are damaged by these interactions depends on susceptibility of the coral and traits of macroalgal competitors. Investigating changes in gene expression of corals and their intracellular symbiotic algae, Symbiodinium, in response to contact with different macroalgae provides insight into the biological processes and cellular pathways affected by competition with macroalgae. We evaluated the gene expression profiles of coral and Symbiodinium genes from two confamilial corals, Acropora millepora and Montipora digitata, after 6 h and 48 h of contact with four common macroalgae that differ in their allelopathic potency to corals. Contacts with macroalgae affected different biological pathways in the more susceptible (A. millepora) versus the more resistant (M. digitata) coral. Genes of coral hosts and of their associated Symbiodinium also responded in species-specific and time-specific ways to each macroalga. Changes in number and expression intensity of affected genes were greater after 6 h compared to 48 h of contact and were greater following contact with Chlorodesmis fastigiata and Amphiroa crassa than following contact with Galaxaura filamentosa or Turbinaria conoides. We documented a divergence in transcriptional responses between two confamilial corals and their associated Symbiodinium, as well as a diversity of dynamic responses within each coral species with respect to the species of macroalgal competitor and the duration of exposure to that competitor. These responses included early initiation of immune processes by Montipora, which is more resistant to damage after long-term macroalgal contact. Activation of the immune response by corals that better resist algal competition is consistent with the hypothesis that some macroalgal effects on corals may be mediated by microbial pathogens.

Show MeSH
Related in: MedlinePlus