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Updated: Jul 14, 2026

Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter
Published on: September 17, 2016
Constitutive expression of CIR1 (RVE2) affects several circadian-regulated processes and seed germination in
Xiangbo Zhang1, Yanhui Chen, Zhi-Yong Wang
1National Laboratory for Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology, College of Life Sciences, Peking University, Beijing 100871, China.
Abstract:
Circadian clocks are endogenous auto-regulatory mechanisms that allow organisms, from bacteria to humans, to advantageously time a wide range of activities within 24 h environmental cycles. Here we report the identification and characterization of an MYB-related gene, designated Circadian 1 (CIR1), that is involved in circadian regulation in Arabidopsis. Expression of CIR1 is transiently induced by light and oscillates with a circadian rhythm. The rhythmic expression of CIR1 is controlled by the central oscillator. Constitutive expression of CIR1 resulted in a shorter period length for the rhythms of four central oscillator components, and much lower amplitude for the rhythms of central oscillator components CCA1 and LHY. Furthermore, CIR1 over-expression severely affected the circadian rhythms of its own RNA and those of the slave oscillator EPR1 and effector genes Lhcb and CAT3. Plants that constitutively expressed CIR1 displayed delayed flowering, longer hypocotyls and reduced seed germination in the dark. These results suggest that CIR1 is possibly part of a regulatory feedback loop that controls a subset of the circadian outputs and modulates the central oscillator.
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