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Molecular insights into the circadian clock in marine diatoms


The circadian clock is a fundamental endogenous mechanism of adaptation that coordinates the physiology and behavior of most organisms with diel variations in the external environment to maintain temporal homeostasis. Diatoms are the major primary producers in the ocean. However, little is known about the circadian clock in marine diatoms compared with other organisms. Here, we investigated circadian clock genes, their expression patterns, and responses to environmental stimuli such as light, nitrogen and phosphorus in two marine diatoms, Skeletonema costatum and Phaeodactylum tricornutum, using a combination of qRT-PCR and bioinformatic analysis. We identified 17 and 18 circadian clock genes in P. tricornutum and S. costatum, respectively. Despite significant evolutionary differences, these genes were similar to those of the higher plant Arabidopsis. We also established a molecular model for the marine diatom circadian clock comprising an input pathway, core oscillator, output pathway, and valve effector. Notably, the expression patterns of core clock genes (circadian clock associated 1 (CCA1), late elongated hypocotyl (LHY) and timing of cab 1 (TOC1)) in both species differed from those of terrestrial plants. Furthermore, the expression of these genes was influenced by variations in ambient light, nitrogen and phosphorus availability. Although marine diatoms and higher plants share common circadian clock components, their clock genes have diverged throughout evolution, likely as a result of adapting to contrasting environments.

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Correspondence to Dazhi Wang.

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Foundation item: The National Natural Science Foundation of China under contract Nos 41425021 and 41706131; the National Key Research and Development Program of China under contract No. 2017YFC1404302; the “Ten Thousand Talents Program” for Leading Talents in Science and Technological Innovation to Dazhi Wang.

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Zhang, S., Wu, Y., Lin, L. et al. Molecular insights into the circadian clock in marine diatoms. Acta Oceanol. Sin. 41, 87–98 (2022).

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Key words

  • circadian clock
  • circadian genes
  • marine diatoms
  • Phaeodactylum tricornutum
  • Skeletonema costatum