Light-Independent Phytochrome Signaling Mediated by Dominant GAF Domain Tyrosine Mutants of<i>Arabidopsis</i>Phytochromes in Transgenic Plants

Su, Yi-shin; Lagarias, J. Clark

doi:10.1105/tpc.107.051516

Cited by 136 publications

(236 citation statements)

References 92 publications

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“…Previous screens have used a COLD, CIRCADIAN RHYTHM AND RNA BINDING2 (CCR2)::LUCIFERASE (LUC) reporter (Columbia accession [Col]) to measure circadian rhythms in the dark (Martin-Tryon et al, 2007), and so we generated Col plants containing both the YHB allele and the CCR2::LUC reporter in addition to introducing a CCA1:: LUC2 reporter into existing YHB (Landsberg erecta [Ler]) lines (Hu et al, 2009). Introduction of the YHB allele confers shortened hypocotyls and expanded cotyledons in Ler seedlings grown in darkness or in constant light (Su and Lagarias, 2007;Hu et al, 2009). Similar short hypocotyls were observed in our newly generated YHB (Col) lines when compared with wildtype Col controls grown under white light (P , 0.05; Fig.…”

Section: Yhb Sustains Core Clock Transcript Cycling In Light-grown Plsupporting

confidence: 58%

“…Previous work has demonstrated that YHB is sufficient to induce photomorphogenesis and to initiate transcriptional cascades that mimic red light-induced phy signaling in the absence of light (Su and Lagarias, 2007;Hu et al, 2009). The circadian system is exquisitely sensitive to changes in day length and light intensity (Salomé et al, 2008;Jones, 2009), so we were curious whether the YHB allele would mimic phyB-mediated light input into the circadian system.…”

Section: Yhb Sustains Core Clock Transcript Cycling In Light-grown Plmentioning

confidence: 99%

“…Following an Wild-type (Col-0) and Col-0 seedlings transformed with a PHYB::PHYB-Y276H construct (YHB) were grown on Murashige and Skoog (MS) medium for 6 d. B, Quantification of hypocotyl lengths of Col-0, YHB (Col-0), Ler, and YHB (Ler) seedlings grown as described in (A). Previously described Ler seedlings similarly transformed with YHB are presented for comparison (Su and Lagarias, 2007). SEM is presented, n .…”

Section: Circadian Period Of Yhb Plants Is Insensitive To Fluence Ratementioning

confidence: 99%

“…C, Immunoblot analysis of phyB/YHB protein levels showing relative phyB accumulation in Col-0 and YHB (Col-0) seedlings. Ler wild type and various transgenic plants harboring the Ler YHB transgenic allele derived from YHB/phyA201phyB-5 line #5 (Su and Lagarias, 2007) are presented for comparison. entrainment period, wild-type, YHB, and phyB-9 seedlings grown on Suc-free medium were released into Rc, with circadian period and amplitude measured via activity of the CCR2::LUC reporter (Fig.…”

Section: Circadian Period Of Yhb Plants Is Insensitive To Fluence Ratementioning

confidence: 99%

“…In addition, period length in phyABCDE mutants is modestly sensitive to different fluence rates of red light (Hu et al, 2013), suggesting that metabolic processes may complicate the assessment of the role of Phys in light input to the circadian clock. To better understand phy-dependent and phy-independent light signaling inputs to the circadian system, we now exploit the phytochrome B-Y276H (YHB) mutant allele that induces constitutive phyB signaling in the absence of light (Su and Lagarias, 2007;Hu et al, 2009). By introducing the YHB allele into the phyABCDE background, we resolve the direct roles of red light from those of phyB activation on clock output/function.…”

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confidence: 99%

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

Jones

Litthauer

et al. 2015

Plant Physiology

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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.

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Section: Yhb Sustains Core Clock Transcript Cycling In Light-grown Plsupporting

confidence: 58%

Section: Yhb Sustains Core Clock Transcript Cycling In Light-grown Plmentioning

confidence: 99%

Section: Circadian Period Of Yhb Plants Is Insensitive To Fluence Ratementioning

confidence: 99%

Section: Circadian Period Of Yhb Plants Is Insensitive To Fluence Ratementioning

confidence: 99%

mentioning

confidence: 99%

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

Jones

Litthauer

et al. 2015

Plant Physiology

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Structural communication between the chromophore‐binding pocket and the N‐terminal extension in plant phytochrome phyB

et al. 2017

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The N-terminal extension (NTE) of plant phytochromes has been suggested to play a functional role in signaling photoinduced structural changes. Here, we use resonance Raman spectroscopy to study the effect of the NTE on the chromophore structure of B-type phytochromes from two evolutionarily distant plants. NTE deletion seems to have no effect on the chromophore in the inactive Pr state, but alters the torsion of the C-D ring methine bridge and the surrounding hydrogen bonding network in the physiologically active Pfr state. These changes are accompanied by a shift of the conformational equilibrium between two Pfr substates, which might affect the thermal isomerization rate of the C-D double bond and, thus, account for the effect of the NTE on the dark reversion kinetics.

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The Role of Phytochromes in Triggering Plant Developmental Transitions

Kaiserli

Chory

2016

Encyclopedia of Life Sciences

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Light is an essential stimulus for energy production, plant growth, development and adaptation to constantly changing environmental conditions. Plants sense different wavelengths of light through the action of specialised families of photoreceptor proteins. The molecular and physiological role of the phytochrome family of red/far‐red light receptors is well characterised. Upon light activation, phytochromes trigger multicomponent signalling cascades to induce fundamental cellular processes ranging from gene expression to protein abundance and nuclear architecture to regulate various aspects of plant development. Phytochrome responses are cell autonomous but in some cases mediate interorgan communication to control major developmental and adaptive responses such as flowering initiation and shade avoidance. Reciprocal interactions and integration between phytochrome and circadian signalling pathways are essential for optimising growth and reproductive success during the life cycle of the model plant Arabidopsis thaliana . Key Concepts Light is a vital informational signal for plant survival and growth. The phytochrome family of plant photoreceptors acts as molecular photoswitches in response to red and far‐red light. Plant phytochrome signal transduction regulates molecular and cellular processes. Phytochromes induce cell‐autonomous responses and interorgan communication. Phytochromes regulate light‐induced developmental transitions as well as adaptation to growth under dense canopy. Plant phytochromes have antagonistic and synergistic roles in regulating photoperiodic flowering in Arabidopsis . Phytochromes inform the endogenous clock about seasonal and daily changes to optimise plant growth and establish reproductive success.

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Light-Independent Phytochrome Signaling Mediated by Dominant GAF Domain Tyrosine Mutants ofArabidopsisPhytochromes in Transgenic Plants

Cited by 136 publications

References 92 publications

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

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

Structural communication between the chromophore‐binding pocket and the N‐terminal extension in plant phytochrome phyB

The Role of Phytochromes in Triggering Plant Developmental Transitions

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