Ambient Temperature Signal Feeds into the Circadian Clock Transcriptional Circuitry Through the EC Night-Time Repressor in Arabidopsis thaliana

Mizuno, Takeshi; Nomoto, Yuji; Oka, Haruka; Kitayama, Miki; Takeuchi, Aya; Tsubouchi, Mayuka; Yamashino, Takafumi

doi:10.1093/pcp/pcu030

Cited by 170 publications

(215 citation statements)

References 65 publications

Supporting

Mentioning

196

Contrasting

Unclassified

Order By: Relevance

“…Another bHLH subfamily, PHYTOCHROME INTERACTING FACTORS 4 and 5 (PIF4 and PIF5), is involved in enhancing flowering at warm temperatures (28°C) by stimulating the expression of FT (41). Furthermore, it has been proposed that temperature signals feed into the clock through the Evening Complex (EC) to regulate the expression of several clock components and also of PIF4 (42). Together, these studies suggest a dual role for FBH1 in modulating the clock response to warm temperatures and the regulation of flowering.…”

Section: Discussionmentioning

confidence: 99%

FBH1 affects warm temperature responses in the Arabidopsis circadian clock

Nagel

Pruneda‐Paz

Kay

2014

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

In Arabidopsis, the circadian clock allows the plant to coordinate daily external signals with internal processes, conferring enhanced fitness and growth vigor. Although external cues such as temperature can entrain the clock, an important feature of the clock is the ability to maintain a relatively constant period over a range of physiological temperatures; this ability is referred to as "temperature compensation." However, how temperature actually is perceived and integrated into the clock molecular circuitry remains largely unknown. In an effort to identify additional regulators of the circadian clock, including putative components that could modulate the clock response to changes in environmental signals, we identified in a previous large-scale screen a transcription factor that interacts with and regulates the promoter activity of a core clock gene. In this report, we characterized this transcription factor, FLOWERING BASIC HELIX-LOOP-HELIX 1 (FBH1) that binds in vivo to the promoter of the key clock gene CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and regulates its expression. We found that upon temperature changes, overexpression of FBH1 alters the pace of CCA1 expression by causing a period shortening and thus preventing the clock from buffering against this change in temperature. Furthermore, as is consistent with the current mechanistic model of feedback loops observed in the clock regulatory network, we also determined that CCA1 binds in vivo to the FBH1 promoter and regulates its expression. Together these results establish a role for FBH1 as a transcriptional modulator of warm temperature signals and clock responses in Arabidopsis.T o adapt better to the daily and seasonal environmental changes, most organisms have an internal timekeeping mechanism known as the "circadian clock." The clock is a self-sustaining machinery that enables organisms to anticipate external fluctuations and in turn coordinate important physiological and developmental processes to occur at optimal times during the day, enhancing fitness (1, 2). In Arabidopsis, the clock consists of a complex network of interlocked regulatory feedback loops between multiple components (3-6). Synchronization of these components with external cues reinforces robust rhythms and allows the clock to coordinate efficiently the regulation of numerous biological outputs such as photosynthesis, photoperiodic flowering, hormone levels, and responses to biotic and abiotic stresses (1,3,(7)(8)(9). Key players in this interconnected network are the transcriptional components CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), two Myb-domain transcription factors, and TIMING OF CAB EXPRESSION 1 (TOC1). These three components, CCA1, LHY, and TOC1, form the core regulatory framework of the Arabidopsis circadian clock; their activity consists of transcriptional repression of each other and direct temporal regulation of most other clock components throughout the day (9-11).Integration and synchronization of environmental signals such as light and te...

show abstract

Section: Discussionmentioning

confidence: 99%

FBH1 affects warm temperature responses in the Arabidopsis circadian clock

Nagel

Pruneda‐Paz

Kay

2014

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…2G,3A,and 6,A and B). ELF4 forms part of the Evening Complex (Nusinow et al, 2011), which directly represses expression of clock genes such as PRR7, PRR9, GI, and ARRHYTHMO (LUX; Herrero et al, 2012;Mizuno et al, 2014;Box et al, 2015). Intriguingly, ELF4 also is necessary for red light-mediated induction of CCA1 and LHY (Kikis et al, 2005).…”

Section: Yhb Mimics Continuous Light Input Into the Circadian System mentioning

confidence: 99%

A Constitutively Active Allele of Phytochrome B Maintains Circadian Robustness in the Absence of Light

Jones

Litthauer

et al. 2015

Plant Physiology

View full text Add to dashboard Cite

The sensitivity of the circadian system to light allows entrainment of the clock, permitting coordination of plant metabolic function and flowering time across seasons. Light affects the circadian system via both photoreceptors, such as phytochromes and cryptochromes, and sugar production by photosynthesis. In the present study, we introduce a constitutively active version of phytochrome B-Y276H (YHB) into both wild-type and phytochrome null backgrounds of Arabidopsis (Arabidopsis thaliana) to distinguish the effects of photoreceptor signaling on clock function from those of photosynthesis. We find that the YHB mutation is sufficient to phenocopy red light input into the circadian mechanism and to sustain robust rhythms in steady-state mRNA levels even in plants grown without light or exogenous sugars. The pace of the clock is insensitive to light intensity in YHB plants, indicating that light input to the clock is constitutively activated by this allele. Mutation of YHB so that it is retained in the cytoplasm abrogates its effects on clock function, indicating that nuclear localization of phytochrome is necessary for its clock regulatory activity. We also demonstrate a role for phytochrome C as part of the red light sensing network that modulates phytochrome B signaling input into the circadian system. Our findings indicate that phytochrome signaling in the nucleus plays a critical role in sustaining robust clock function under red light, even in the absence of photosynthesis or exogenous sources of energy.

show abstract

“…Hypocotyl elongation is controlled by several signaling pathways that converge upon phytohormones to regulate cell expansion (Lincoln et al, 1990;Collett et al, 2000). Examples of signals that adjust hypocotyl elongation include phytochrome-mediated signals concerning the ratio of red to far red light (Casal, 2013), blue light (Liscum and Hangarter, 1991), UV-B light (Kim et al, 1998;Hayes et al, 2014), temperature (Koini et al, 2009;Wigge, 2013;Mizuno et al, 2014), photoperiod and the circadian oscillator (Dowson-Day and Millar, 1999;Más et al, 2003;Nusinow et al, 2011). These signals are integrated by the PHYTOCHROME INTERACTING FACTOR (PIF) family of basic helix-loop-helix transcription factors.…”

mentioning

confidence: 99%

The Energy-Signaling Hub SnRK1 Is Important for Sucrose-Induced Hypocotyl Elongation

et al. 2017

View full text Add to dashboard Cite

Emerging seedlings respond to environmental conditions such as light and temperature to optimize their establishment. Seedlings grow initially through elongation of the hypocotyl, which is regulated by signaling pathways that integrate environmental information to regulate seedling development. The hypocotyls of Arabidopsis (Arabidopsis thaliana) also elongate in response to sucrose. Here, we investigated the role of cellular sugar-sensing mechanisms in the elongation of hypocotyls in response to Suc. We focused upon the role of SnRK1, which is a sugar-signaling hub that regulates metabolism and transcription in response to cellular energy status. We also investigated the role of TPS1, which synthesizes the signaling sugar trehalose-6-P that is proposed to regulate SnRK1 activity. Under light/dark cycles, we found that Suc-induced hypocotyl elongation did not occur in tps1 mutants and overexpressors of KIN10 (AKIN10/SnRK1.1), a catalytic subunit of SnRK1. We demonstrate that the magnitude of Suc-induced hypocotyl elongation depends on the day length and light intensity. We identified roles for auxin and gibberellin signaling in Suc-induced hypocotyl elongation under short photoperiods. We found that Suc-induced hypocotyl elongation under light/dark cycles does not involve another proposed sugar sensor, HEXOKINASE1, or the circadian oscillator. Our study identifies novel roles for KIN10 and TPS1 in mediating a signal that underlies Suc-induced hypocotyl elongation in light/dark cycles.

show abstract

Ambient Temperature Signal Feeds into the Circadian Clock Transcriptional Circuitry Through the EC Night-Time Repressor in Arabidopsis thaliana

Cited by 170 publications

References 65 publications

FBH1 affects warm temperature responses in the Arabidopsis circadian clock

FBH1 affects warm temperature responses in the Arabidopsis circadian clock

A Constitutively Active Allele of Phytochrome B Maintains Circadian Robustness in the Absence of Light

The Energy-Signaling Hub SnRK1 Is Important for Sucrose-Induced Hypocotyl Elongation

Contact Info

Product

Resources

About