Differential transcriptional responses of carotenoid biosynthesis genes in the marine green alga Tetraselmis suecica exposed to redox and non-redox active metals
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The green microalga, Tetraselmis suecica, is commonly used in scientific, industrial, and aquacultural purposes because of its high stress tolerance and ease of culture in wide spectrums of environments. We hypothesized that carotenoids help to protect Tetraselmis cells from environmental stress by regulating genes in biosynthetic pathways. Here, we determined three major carotenogenic genes, phytoene synthase (PSY), phytoene desaturase (PDS), and β-lycopene cyclase (LCY-B) in T. suecica, and examined the physiological parameters and gene expression responses when exposed to redox-active metals and non-redox-active metals. Phylogenetic analyses of each gene indicated that T. suecica clustered well with other green algae. Real-time PCR analysis showed that TsPSY, TsPDS, and TsLCY-B genes greatly responded to the redox-active metals in CuSO4 followed by CuCl2, but not to the non-redox-active metals. The redox-active metals strongly affected the physiology of the cells, as determined by cell counting, reactive oxygen species (ROS) imaging, and photosynthetic efficiency. This suggests that carotenoids protect the cells from oxidative damage caused by metals, thereby contributing to cell survival under various stress conditions.
KeywordsGene expression Marine green algae Carotenoids Non-redox-active metals Redox-active metals Tetraselmis suecica
We thank Dr. H. Wang for critical comments on the early version of manuscript. This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (2015M1A5A1041805 and 2016R1D1A1A09920198), and by a grant from the National Institute of Fisheries Science (R2018043) funded to J.-S. Ki.
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies conducted on human or animal subjects.
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