Real-time PCR reveals a high incidence of Symbiodinium clade D at low levels in four scleractinian corals across the Great barrier Reef : implications for symbiont shuffling

• Published in: Coral reefs Vol. 26; no. 3; pp. 449 - 457
• Main Authors: MIEOG, J. C, VAN OPPEN, M. J. H, CANTIN, N. E, STAM, W. T, OLSEN, J. L
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-09-2007; Berlin Springer Nature B.V
• Subjects: Acropora millepora; Acropora tenuis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Climate change; Cnidaria. Ctenaria; Coral reefs; Environmental impact; Fundamental and applied biological sciences. Psychology; Global warming; Invertebrates; Marine; Microbiology; Scleractinia; Sea water ecosystems; Stylophora pistillata; Symbiodinium; Symbiosis; Synecology; Turbinaria reniformis; Australia; Oceania; Great Barrier Reef; ISEW, Australia, Queensland, Great Barrier Reef; Algae; Coral reef; Real time; Scleractinia; Symbiont; Polymerase chain reaction; Zooxanthella, Background clade,Shuffling; Coelenterata; Dinophyta; Coral, Symbiodinium; Real-time PCR; Coral; Cnidaria; Invertebrata; Thallophyta; Great Barrier Reef
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-007-0244-8

Reef corals form associations with an array of genetically and physiologically distinct endosymbionts from the genus Symbiodinium. Some corals harbor different clades of symbionts simultaneously, and over time the relative abundances of these clades may change through a process called symbiont shuffling. It is hypothesized that this process provides a mechanism for corals to respond to environmental threats such as global warming. However, only a minority of coral species have been found to harbor more than one symbiont clade simultaneously and the current view is that the potential for symbiont shuffling is limited. Using a newly developed real-time PCR assay, this paper demonstrates that previous studies have underestimated the presence of background symbionts because of the low sensitivity of the techniques used. The assay used here targets the multi-copy rDNA ITS1 region and is able to detect Symbiodinium clades C and D with >100-fold higher sensitivity compared to conventional techniques. Technical considerations relating to intragenomic variation, estimating copy number and non-symbiotic contamination are discussed. Eighty-two colonies from four common scleractinian species (Acropora millepora, Acropora tenuis, Stylophora pistillata and Turbinaria reniformis) and 11 locations on the Great Barrier Reef were tested for background Symbiodinium clades. Although these colonies had been previously identified as harboring only a single clade based on SSCP analyses, background clades were detected in 78% of the samples, indicating that the potential for symbiont shuffling may be much larger than currently thought.[PUBLICATION ABSTRACT]