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 inmarine diatoms compared with other organisms. Here, we investigated circadian clock genes, their expressionpatterns, 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 bioinformaticanalysis. We identified 17 and 18 circadian clock genes in P. tricornutum and S. costatum, respectively. Despitesignificant evolutionary differences, these genes were similar to those of the higher plant Arabidopsis. We alsoestablished a molecular model for the marine diatom circadian clock comprising an input pathway, coreoscillator, output pathway, and valve effector. Notably, the expression patterns of core clock genes (circadianclock associated 1 (CCA1), late elongated hypocotyl (LHY) and timing of cab 1 (TOC1)) in both species differedfrom those of terrestrial plants. Furthermore, the expression of these genes was influenced by variations inambient light, nitrogen and phosphorus availability. Although marine diatoms and higher plants share commoncircadian clock components, their clock genes have diverged throughout evolution, likely as a result of adapting tocontrasting environments.

Shufeng Zhang;Yue Wu;Lin Lin;Dazhi Wang

State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China;College of the Environment and Ecology, Xiamen University, Xiamen 361102, China;Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

海洋学报（英文版）

[1]Shufeng Zhang;Yue Wu;Lin Lin;Dazhi Wang-.Molecular insights into the circadian clock in marine diatoms)[J].海洋学报（英文版）,2022(08):87-98

inmarine,expressionpatterns,bioinformaticanalysis,Despitesignificant,alsoestablished,coreoscillator,circadianclock,LHY,differedfrom,inambient,commoncircadian,tocontrasting

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