Transcriptomic analysis of thermally stressed Symbiodinium reveals differential expression of stress and metabolism genes

Gierz, Sarah, Forêt, Sylvain, and Leggat, William (2017) Transcriptomic analysis of thermally stressed Symbiodinium reveals differential expression of stress and metabolism genes. Frontiers in Plant Science, 8. 271. pp. 1-20.

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Endosymbioses between dinoflagellate algae (Symbiodinium sp.) and scleractinian coral species form the foundation of coral reef ecosystems. The coral symbiosis is highly susceptible to elevated temperatures, resulting in coral bleaching, where the algal symbiont is released from host cells. This experiment aimed to determine the transcriptional changes in cultured Symbiodinium, to better understand the response of cellular mechanisms under future temperature conditions. Cultures were exposed to elevated temperatures (average 31°C) or control conditions (24.5°C) for a period of 28 days. Whole transcriptome sequencing of Symbiodinium cells on days 4, 19, and 28 were used to identify differentially expressed genes under thermal stress. A large number of genes representing 37.01% of the transcriptome (∼23,654 unique genes, FDR < 0.05) with differential expression were detected at no less than one of the time points. Consistent with previous studies of Symbiodinium gene expression, fold changes across the transcriptome were low, with 92.49% differentially expressed genes at ≤2-fold change. The transcriptional response included differential expression of genes encoding stress response components such as the antioxidant network and molecular chaperones, cellular components such as core photosynthesis machinery, integral light-harvesting protein complexes and enzymes such as fatty acid desaturases. Differential expression of genes encoding glyoxylate cycle enzymes were also found, representing the first report of this in Symbiodinium. As photosynthate transfer from Symbiodinium to coral hosts provides up to 90% of a coral’s daily energy requirements, the implications of altered metabolic processes from exposure to thermal stress found in this study on coral-Symbiodinium associations are unknown and should be considered when assessing the stability of the symbiotic relationship under future climate conditions.

Item ID: 47474
Item Type: Article (Research - C1)
ISSN: 1664-462X
Keywords: Symbiodinium; thermal stress; transcriptome; gene expression; dinoflagellate; coral; bleaching; RNA-Seq
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Copyright © 2017 Gierz, Forêt and Leggat. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Funders: Australian Research Council Centre of Excellence for Coral Reef Studies (ARC CECRS), Australian Research Council (ARC)
Projects and Grants: ARC CECRS CE140100020, ARC Discovery Project DP130101421, ARC Discovery Project DP160100271
Research Data:
Date Deposited: 24 Mar 2017 02:25
FoR Codes: 31 BIOLOGICAL SCIENCES > 3101 Biochemistry and cell biology > 310199 Biochemistry and cell biology not elsewhere classified @ 30%
31 BIOLOGICAL SCIENCES > 3105 Genetics > 310505 Gene expression (incl. microarray and other genome-wide approaches) @ 50%
31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310801 Phycology (incl. marine grasses) @ 20%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960399 Climate and Climate Change not elsewhere classified @ 40%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 40%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 20%
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