The APRR1/TOC1 Quintet Implicated in Circadian Rhythms of Arabidopsis thaliana: I. Characterization with APRR1-Overexpressing Plants

Makino, Seiya; Matsushika, Akinori; Kojima, Masaru; Yamashino, Takafumi; Mizuno, Takeshi

doi:10.1093/pcp/pcf005

Cited by 193 publications

(172 citation statements)

References 46 publications

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“…If the oscillating mRNA and protein abundance of a clock component, such as TOC1, is necessary for oscillator function but becomes pegged at a constant high level through overexpression, arrhythmicity should result. Indeed, TOC1 overexpressors are arrhythmic (Makino et al, 2002;Má s et al, 2003b). CCA1 was identified initially as binding to the LHCB1*3 promoter.…”

Section: The Current Paradigm Applied To Plants: a Model Of The Plantmentioning

confidence: 99%

Plant Circadian Rhythms

2006

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Section: The Current Paradigm Applied To Plants: a Model Of The Plantmentioning

confidence: 99%

Plant Circadian Rhythms

2006

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“…2E) and elevated expression of genes, such as PHYTOCHROME-INTERACTING FACTOR3 (PIF3)-LIKE1 (PIL1; Fig. 2F), whose expression is induced by low R:FR ratios (Makino et al, 2002;Salter et al, 2003). To determine whether FLC levels are affected by FREL, we examined FLC mRNA levels under WL or FREL.…”

Section: Frel Promotes Flowering In Fri and Autonomous-pathway Mutantmentioning

confidence: 99%

Regulation of CONSTANS and FLOWERING LOCUS T Expression in Response to Changing Light Quality

Kim¹,

Yu²,

Michaels³

2008

Plant Physiol.

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In addition to pathways that regulate flowering in response to environmental signals such as photoperiod or cold temperatures (vernalization), flowering time is also regulated by light quality. In many species, far-red (FR) light is known to accelerate flowering. This is environmentally significant because leaves absorb more red light than FR light; thus, plants growing under a canopy experience light that is enriched in FR light. In this article, we have explored the promotion of flowering by FRenriched light (FREL) in Arabidopsis (Arabidopsis thaliana). Previous work has shown that the floral promoter CONSTANS (CO) plays a critical role in day-length perception and exhibits complex regulation; CO mRNA is regulated by the circadian clock and CO protein is stabilized by light and degraded in darkness. We find that plants grown under FREL contain higher levels of CO mRNA in the early part of the day than plants under white light. Furthermore, transgenic plants expressing CO under the control of a constitutive promoter accumulate higher levels of CO protein under FREL, indicating that FREL can increase CO protein levels independently of transcription. Consistent with the model that FREL promotes flowering through CO, mutants for co or gigantea, which are required for CO transcript accumulation, are relatively insensitive to FREL. Because the red:FR ratios used in these experiments are in the range of what plants would experience under a canopy, these results indicate that the regulation of CO by light quality likely plays a key role in the regulation of flowering time in natural environments.

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“…The hypothesized role of TOC1 as a transcription factor is based on similarity to CONSTANS, although DNA binding by TOC1 has not been experimentally established (Strayer et al, 2000). However, TOC1 (APRR1) has been shown to bind to PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), a Myc-related basic helix-loop-helix transcription factor, and to the related PIF3-LIKE 1 (PIL1; Makino et al, 2002). Expression of each of the three clock components, TOC1, CCA1, and LHY, is circadian regulated (Schaffer et al, 1998;Wang and Tobin, 1998;Matsushika et al, 2000;Strayer et al, 2000).…”

mentioning

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Phase-Specific Circadian Clock Regulatory Elements in Arabidopsis

2002

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We have defined a minimal Arabidopsis CATALASE 3 (CAT3) promoter sufficient to drive evening-specific circadian transcription of a LUCIFERASE reporter gene. Deletion analysis and site-directed mutagenesis reveal a circadian response element, the evening element (EE: AAAATATCT), that is necessary for evening-specific transcription. The EE differs only by a single base pair from the CIRCADIAN CLOCK ASSOCIATED 1-binding site (CBS: AAAAAATCT), which is important for morning-specific transcription. We tested the hypothesis that the EE and the CBS specify circadian phase by site-directed mutagenesis to convert the CAT3 EE into a CBS. Changing the CAT3 EE to a CBS changes the phase of peak transcription from the evening to the morning in continuous dark and in light-dark cycles, consistent with the specification of phase by the single base pair that distinguishes these elements. However, rhythmicity of the CBS-containing CAT3 promoter is dramatically compromised in continuous light. Thus, we conclude that additional information normally provided in the context of a morning-specific promoter is necessary for full circadian activity of the CBS.The circadian clock enables an organism to specifically partition aspects of its biology to precise times over the day (Dunlap, 1999). Although the circadian clock is, by definition, endogenous and continues to run in the absence of external time cues, environmental stimuli such as light and temperature act to entrain the internal processes of an organism both to the exact external daily period and in a defined relationship, or phase angle, to the diurnal cycle. For example, in Arabidopsis, light and temperature information are integrated to partition physiological activities such as circadian-regulated leaf movement, stomatal opening, and gene expression to distinct times of day or phases (McClung et al., 2002).A central theme that has emerged in circadian biology is that the core oscillator is composed of a negative feedback loop grounded in positive and negative transcriptional regulation (Dunlap, 1999). It has recently been demonstrated that the Arabidopsis circadian clock entails such a transcriptional feedback loop (Alabadí et al., 2001) that includes at least three components: TIMING OF CAB EXPRESSION 1 (TOC1; also called Arabidopsis PSEUDO-RESPONSE REGULATOR 1, APRR1; Millar et al., 1995;, CIRCADIAN CLOCK ASSOCIATED 1 (CCA1; Wang and Tobin, 1998), and LATE ELON-GATED HYPOCOTYL (LHY; Schaffer et al., 1998).CCA1 and LHY are single-Myb domain transcription factors, and DNA-binding activity of CCA1 to a CCA1-binding site (CBS: AAAAATCT) has been characterized (Wang et al., 1997). The hypothesized role of TOC1 as a transcription factor is based on similarity to CONSTANS, although DNA binding by TOC1 has not been experimentally established (Strayer et al., 2000). However, TOC1 (APRR1) has been shown to bind to PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), a Myc-related basic helix-loop-helix transcription factor, and to the related PIF3-LIKE 1 (PIL1; Makino et al., 2002). Expression o...

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The APRR1/TOC1 Quintet Implicated in Circadian Rhythms of Arabidopsis thaliana: I. Characterization with APRR1-Overexpressing Plants

Cited by 193 publications

References 46 publications

Plant Circadian Rhythms

Plant Circadian Rhythms

Regulation of CONSTANS and FLOWERING LOCUS T Expression in Response to Changing Light Quality

Phase-Specific Circadian Clock Regulatory Elements in Arabidopsis

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