Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock

Kamioka, Mari; Takao, Saori; Suzuki, Takamasa; Taki, Kazumi; Higashiyama, Tetsuya; Kinoshita, Toshinori; Nakamichi, Norihito

doi:10.1105/tpc.15.00737

Cited by 212 publications

(242 citation statements)

References 97 publications

(160 reference statements)

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“…Previously, genetic results implied that CCA1 and LHY directly act as transcriptional activators for the morningphased genes PSEUDO RESPONSE REGULATOR9 (PRR9) and PRR7 (Farré et al, 2005). However, recent transient induction analysis demonstrated that CCA1 can directly repress the expression of both PRR9 and PRR7 (Kamioka et al, 2016), suggesting that the previous result can be caused by indirect effects of cca1 and lhy mutations.…”

Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 98%

“…1). At dawn, two MYB transcription factors, CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), repress evening-phased genes (Nagel et al, 2015;Kamioka et al, 2016). This repression is partly dependent on the function of the CONSTITUTIVE PHOTOMORPHOGENIC10 (COP10)-DE-ETIOLATED1-DAMAGED DNA BINDING1 complex, a negative regulator for photomorphogenesis (Lau et al, 2011).…”

Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 99%

“…Chromatin immunoprecipitation sequencing analyses brought us, to our knowledge, a new insight regarding potential variation in CCA1 binding sites. In addition to Evening Element and the CCA1 Binding Site, DNA motifs that contain G-box or CT repeats are significantly enriched in the CCA1 binding regions (Nagel et al, 2015;Kamioka et al, 2016), indicating that CCA1 may form complexes with different transcription factors that alter the DNA binding preferences of complexes that contain CCA1. Previously, genetic results implied that CCA1 and LHY directly act as transcriptional activators for the morningphased genes PSEUDO RESPONSE REGULATOR9 (PRR9) and PRR7 (Farré et al, 2005).…”

Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 99%

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Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

2016

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Plants sense changes in day length (= photoperiod) as a reliable seasonal cue to regulate important developmental transitions such as flowering. Integration of various external light information into the circadian clock-controlled mechanisms enables plants to precisely measure photoperiod changes in the surrounding environment. The core mechanism of photoperiodic measurement is regulation of CONSTANS (CO) activity, which takes place in phloem companion cells in leaves. Until recently, it remained unclear whether plants possess specific variations of the clock for this regulation. Now it is known that a specific circadian timing mechanism in the vascular tissue is essential for photoperiodic flowering. In addition to spatial tissue-specific regulation, temporal regulation of CO activity is also important. The identification and characterization of multiple regulators that physically interact with CO and influence its function in the morning in long days are two recent advances in photoperiodic regulation of flowering time. It seems that CO acts as a network hub to integrate various external and internal signals into the photoperiodic flowering pathway. CO regulates the amount of FLOWERING LOCUS T (FT) transcripts and FT protein moves from companion cells of leaf phloem to the shoot apical meristem. The protein that helps long-distance transport of FT protein was also identified recently. Here, we introduce recent advances in tissue-specific variations of the circadian clock and the emerging picture of the intricate connections of transcriptional regulators through CO in the morning, which all facilitate plants knowing when to flower.Properly timing the floral transition is crucial for reproductive success. It can also influence the early development of offspring. To optimize this timing, plants constantly monitor changes in the surrounding environment. Among various environmental factors, observing changes in day length (= photoperiod) is the most reliable way for many organisms to know the specific time of year. Therefore, photoperiodic regulation is one of the major flowering time mechanisms and it has been studied since it was first reported in 1920 (Song et al., 2015). Arabidopsis (Arabidopsis thaliana), as it flowers mainly in spring, can sense lengthening days to induce flowering and became a suitable model to study photoperiodic flowering regulation. (Andrés and Coupland, 2012;Song et al., 2013;Pajoro et al., 2014;Shim and Imaizumi, 2015).In principle, photoperiodic flowering mechanisms can be divided into three parts: light input, circadian clock, and output. Light information is integrated into innate photoperiodic timing mechanisms governed by the circadian clock to induce genes that trigger flowering.

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Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 98%

Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 99%

Section: A Molecular Framework Of the Circadian Oscillatormentioning

confidence: 99%

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Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

2016

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“…TOC1 (also known as PRR1) represses transcription of CCA1 and LHY (Huang et al, 2012). CCA1 and LHY also repress transcription of EARLY FLOWERING3 (ELF3),ELF4,LUXARRHYTHMO(LUX;alsoknownasPHYTOCLOCK1), PRR5, and GIGANTEA (GI), and they all positively regulate expression of CCA1 and LHY except PRR5 (Hazen et al, 2005;Kikis et al, 2005;Onai and Ishiura, 2005;Kamioka et al, 2016). In addition, CCA1 and LHY promote transcription of two TOC1 homologs, PRR7 and PRR9, as they in turn, repress expression of CCA1 and LHY (Farré et al, 2005;Nakamichi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Blue Light- and Low Temperature-Regulated COR27 and COR28 Play Roles in the Arabidopsis Circadian Clock

et al. 2016

Plant Cell

104

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Light and temperature are two key environmental signals that profoundly affect plant growth and development, but underlying molecular mechanisms of how light and temperature signals affect the circadian clock are largely unknown. Here, we report that COR27 and COR28 are regulated not only by low temperatures but also by light signals. COR27 and COR28 are negative regulators of freezing tolerance but positive regulators of flowering, possibly representing a trade-off between freezing tolerance and flowering. Furthermore, loss-of-function mutations in COR27 and COR28 result in period lengthening of various circadian output rhythms and affect central clock gene expression. Also, the cor27 cor28 double mutation affects the pace of the circadian clock. Additionally, COR27 and COR28 are direct targets of CCA1, which represses their transcription via chromatin binding. Finally, we report that COR27 and COR28 bind to the chromatin of TOC1 and PRR5 to repress their transcription, suggesting that their effects on rhythms are in part due to their regulation of TOC1 and PRR5. These data demonstrate that blue light and low temperature-regulated COR27 and COR28 regulate the circadian clock as well as freezing tolerance and flowering time.

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“…In turn, the expression of EC genes and formation of the EC itself are also tightly regulated by the circadian clock through multiple regulatory mechanisms (Herrero et al, 2012;Choudhary et al, 2015). The ELF3, ELF4, and LUX promoters are bound by the key clock protein CCA1, a morning phased myb transcription factor that acts together with its paralog LATE ELONGATED HYPOCOTYL (LHY) to repress evening-phased genes during the day (Lu et al, 2012;Adams et al, 2015;Nagel et al, 2015;Kamioka et al, 2016). Autoregulation of the EC may also be achieved through binding of the LUX protein to its own promoter .…”

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confidence: 99%

EARLY FLOWERING3 Redundancy Fine-Tunes Photoperiod Sensitivity

et al. 2017

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Three pea (Pisum sativum) loci controlling photoperiod sensitivity, HIGH RESPONSE (HR), DIE NEUTRALIS (DNE), and STERILE NODES (SN), have recently been shown to correspond to orthologs of Arabidopsis (Arabidopsis thaliana) circadian clock genes EARLY FLOWERING3 (ELF3), ELF4, and LUX ARRHYTHMO, respectively. A fourth pea locus, PHOTOPERIOD (PPD), also contributes to the photoperiod response in a similar manner to SN and DNE, and recessive ppd mutants on a springflowering hr mutant background show early, photoperiod-insensitive flowering. However, the molecular identity of PPD has so far remained elusive. Here, we show that the PPD locus also has a role in maintenance of diurnal and circadian gene expression rhythms and identify PPD as an ELF3 co-ortholog, termed ELF3b. Genetic interactions between pea ELF3 genes suggest that loss of PPD function does not affect flowering time in the presence of functional HR, whereas PPD can compensate only partially for the lack of HR. These results provide an illustration of how gene duplication and divergence can generate potential for the emergence of more subtle variations in phenotype that may be adaptively significant.

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Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock

Cited by 212 publications

References 97 publications

Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

Blue Light- and Low Temperature-Regulated COR27 and COR28 Play Roles in the Arabidopsis Circadian Clock

EARLY FLOWERING3 Redundancy Fine-Tunes Photoperiod Sensitivity

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