Cloning of the
            <i>Arabidopsis</i>
            Clock Gene
            <i>TOC1</i>
            , an Autoregulatory Response Regulator Homolog

Strayer, Carl A.; Oyama, Tokitaka; Schultz, Thomas F.; Raman, Ramanujam; Somers, David E.; Más, Paloma Díaz; Panda, Satchidananda; Kreps, Joel A.; Kay, Steve A.

doi:10.1126/science.289.5480.768

Cited by 771 publications

(744 citation statements)

References 22 publications

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“…However, if the clock system is reset by the light-to-dark transition at dusk, expression of these genes should rise at a constant time after transfer to DD regardless of when LL begins. Expression of PnLHY and PnTOC1 exhibited circadian rhythms peaking approximately at circadian time (CT) 0 in the subjective morning and CT 8 in the subjective evening, respectively, consistent with peak times in circadian expression of LHY and TOC1 in Arabidopsis, 24,25 (Figure 1B,E, H, K, Supplementary Figure 1A-D). Expression of both of these genes also began to rise constantly from transfer to LL, indicating that circadian phases in expression of PnLHY and PnTOC1 are set by the dark-to-light transition without being affected by light-to-dark transitions (Figure 1B,E, H, K, Supplementary Figure 1A-D).…”

supporting

confidence: 68%

Differential effects of light-to-dark transitions on phase setting in circadian expression among clock-controlled genes in Pharbitis nil

Hayama

Mizoguchi

Coupland

2018

Plant Signaling & Behavior

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The circadian clock is synchronized by the day-night cycle to allow plants to anticipate daily environmental changes and to recognize annual changes in day length enabling seasonal flowering. This clock system has been extensively studied in Arabidopsis thaliana and was found to be reset by the dark to light transition at dawn. By contrast, studies on photoperiodic flowering of Pharbitis nil revealed the presence of a clock system reset by the transition from light to dark at dusk to measure the duration of the night. However, a Pharbitis photosynthetic gene was also shown to be insensitive to this dusk transition and to be set by dawn. Thus Pharbitis appeared to have two clock systems, one set by dusk that controls photoperiodic flowering and a second controlling photosynthetic gene expression similar to that of Arabidopsis. Here, we show that circadian mRNA expression of Pharbitis homologs of a series of Arabidopsis clock or clock-controlled genes are insensitive to the dusk transition. These data further define the presence in Pharbitis of a clock system that is analogous to the Arabidopsis system, which co-exists and functions with the dusk-set system dedicated to the control of photoperiodic flowering.

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supporting

confidence: 68%

Differential effects of light-to-dark transitions on phase setting in circadian expression among clock-controlled genes in Pharbitis nil

Hayama

Mizoguchi

Coupland

2018

Plant Signaling & Behavior

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“…PRRs were originally identified as components of the circadian clock in A. thaliana and generally proposed to contribute to day‐length measurement through control of the time‐keeping mechanism associated with CO transcription (Strayer et al , 2000; Yanovsky & Kay, 2002; Ito et al , 2003, 2008; Yamamoto et al , 2003; Murakami et al , 2004; Nakamichi et al , 2007; Para et al , 2007). By contrast, we defined a previously unidentified role of these circadian‐clock components in regulating CO activity, where they interact with and stabilize CO protein during the day, ensuring its accumulation under LDs.…”

Section: Discussionmentioning

confidence: 99%

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

et al. 2017

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Seasonal reproduction in many organisms requires detection of day length. This is achieved by integrating information on the light environment with an internal photoperiodic time‐keeping mechanism. Arabidopsis thaliana promotes flowering in response to long days (LDs), and CONSTANS (CO) transcription factor represents a photoperiodic timer whose stability is higher when plants are exposed to light under LDs. Here, we show that PSEUDO RESPONSE REGULATOR (PRR) proteins directly mediate this stabilization. PRRs interact with and stabilize CO at specific times during the day, thereby mediating its accumulation under LDs. PRR‐mediated stabilization increases binding of CO to the promoter of FLOWERING LOCUS T (FT), leading to enhanced FT transcription and early flowering under these conditions. PRRs were previously reported to contribute to timekeeping by regulating CO transcription through their roles in the circadian clock. We propose an additional role for PRRs in which they act upon CO protein to promote flowering, directly coupling information on light exposure to the timekeeper and allowing recognition of LDs.

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“…PIF3, a basic helix-loop-helixclass transcriptional regulator, interacts specifically with the Pfr form of phy while bound to its DNA target site and appears to be involved in Rc-regulated gene expression (for review, see Quail, 2002). There is a growing list of other proteins that are also nuclear localized and implicated in phy-mediated signaling, including some that are involved in the circadian clock and photoperiod sensitivity, like ELF3, GI, TOC1, and PSEUDO RESPONSE REGULATOR 7 (Huq et al, 2000;Strayer et al, 2000;Liu et al, 2001;Kaczorowski and Quail, 2003). As we show here, ELF4 is also localized to the nucleus (Fig.…”

Section: Discussionmentioning

confidence: 99%

EARLY FLOWERING 4Functions in Phytochrome B-Regulated Seedling De-Etiolation

Khanna

Kikis²,

Quail³

2003

Plant Physiology

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To define the functions of genes previously identified by expression profiling as being rapidly light induced under phytochrome (phy) control, we are investigating the seedling de-etiolation phenotypes of mutants carrying T-DNA insertional disruptions at these loci. Mutants at one such locus displayed reduced responsiveness to continuous red, but not continuous far-red light, suggesting a role in phyB signaling but not phyA signaling. Consistent with such a role, expression of this gene is induced by continuous red light in wild-type seedlings, but the level of induction is strongly reduced in phyB-null mutants. The locus encodes a novel protein that we show localizes to the nucleus, thus suggesting a function in light-regulated gene expression. Recently, this locus was identified as EARLY FLOWERING 4, a gene implicated in floral induction and regulating the expression of the gene CIRCADIAN CLOCK-ASSOCIATED 1. Together with these previous data, our findings suggest that EARLY FLOWERING 4 functions as a signaling intermediate in phy-regulated gene expression involved in promotion of seedling de-etiolation, circadian clock function, and photoperiod perception.

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Cloning of the Arabidopsis Clock Gene TOC1 , an Autoregulatory Response Regulator Homolog

Cited by 771 publications

References 22 publications

Differential effects of light-to-dark transitions on phase setting in circadian expression among clock-controlled genes in Pharbitis nil

Differential effects of light-to-dark transitions on phase setting in circadian expression among clock-controlled genes in Pharbitis nil

PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length

EARLY FLOWERING 4Functions in Phytochrome B-Regulated Seedling De-Etiolation

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