Featured
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| Open AccessResponses of unicellular predators to cope with the phototoxicity of photosynthetic prey
Photosynthesis generates reactive oxygen species that can damage cells. Here, the authors show that unicellular predators of photosynthetic prey have shared responses to photosynthetic oxidative stress and these may also have been important for the evolution of endosymbiosis.
- Akihiro Uzuka
- , Yusuke Kobayashi
- & Shin-ya Miyagishima
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Review Article
| Open AccessMolecular mechanisms underlying phytochrome-controlled morphogenesis in plants
Perception of red and far-red light by photosensory phytochromes regulates plant development and adaptive responses to light. Here, Legris et al. review current models of phytochrome function connecting light-induced conformational changes to physiological outputs and highlight open questions for future research.
- Martina Legris
- , Yetkin Çaka Ince
- & Christian Fankhauser
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Article
| Open AccessUVR8 disrupts stabilisation of PIF5 by COP1 to inhibit plant stem elongation in sunlight
UV-B light suppresses the shade avoidance response in plants by reducing the abundance of PIF transcription factors by an undefined mechanism. Here the authors show that UV-B perceived by the UVR8 receptor inhibits the shade avoidance response by preventing stabilisation of PIF5 by COP1.
- Ashutosh Sharma
- , Bhavana Sharma
- & Keara A. Franklin
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Article
| Open AccessA phyB-PIF1-SPA1 kinase regulatory complex promotes photomorphogenesis in Arabidopsis
SPA proteins repress plant photomorphogenesis by promoting the E3 ligase activity of COP1. Here the authors show that SPAs also act as serine/threonine kinase and are required for phyB-mediated light-dependent phosphorylation and degradation of the PIF1 transcription factor.
- Inyup Paik
- , Fulu Chen
- & Enamul Huq
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Article
| Open AccessThe CONSTANS flowering complex controls the protective response of photosynthesis in the green alga Chlamydomonas
In flowering plants, the CONSTANS (CO) and Nuclear Factor Y (NF-Y) transcription factors connect light perception to floral induction. Here Tokutsu et al. show that in the green alga Chlamydomonas, CO and NF-Y form an analogous complex that can prevent photodamage in response to excess light.
- Ryutaro Tokutsu
- , Konomi Fujimura-Kamada
- & Jun Minagawa
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Article
| Open AccessPIF transcription factors link a neighbor threat cue to accelerated reproduction in Arabidopsis
In plants, phytochrome B senses light cues indicative of neighbouring competitors leading to accelerated flowering. Here the authors show that PHYTOCHROME INTERACTING FACTORs 4, 5 and 7 (PIF4, PIF5 and PIF7) mediate neighbor proximity-induced flowering acting downstream of phyB to promote expression of FT and TSF.
- Vinicius Costa Galvāo
- , Anne-Sophie Fiorucci
- & Christian Fankhauser
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Article
| Open AccessPlant circadian rhythms regulate the effectiveness of a glyphosate-based herbicide
Glyphosate is the world’s most widely-used herbicide. Here, Belbin et al. show that plant responses to glyphosate, and therefore herbicide activity, depend on plant circadian rhythms suggesting that considering the time-of-day of application could lead to more efficient agrochemical use.
- Fiona E. Belbin
- , Gavin J. Hall
- & Antony N. Dodd
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Article
| Open AccessSHB1 and CCA1 interaction desensitizes light responses and enhances thermomorphogenesis
The PIF4 transcription factor promotes adaptation to elevated temperature but is degraded under red light to trigger photomorphogenesis. Here Sun et al. show that the core circadian component CCA1 recruits SHB1 to sustain PIF4 expression after dawn to balance thermomorphogenesis and light responses.
- Qingbin Sun
- , Shulei Wang
- & Min Ni
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Article
| Open AccessOrthogonal regulation of phytochrome B abundance by stress-specific plastidial retrograde signaling metabolite
MEcPP is an evolutionarily conserved metabolite that acts as a plastid-to-nucleus retrograde signal to regulate adaptive responses to fluctuating light. Here the authors show that MEcPP regulates seedling development by stabilizing the phyB photoreceptor in an auxin and Ca2+ dependent manner.
- Jishan Jiang
- , Liping Zeng
- & Katayoon Dehesh
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Article
| Open AccessNCP activates chloroplast transcription by controlling phytochrome-dependent dual nuclear and plastidial switches
Phytochrome signaling in the nucleus can activate expression of photosynthesis-associated genes in plastids. Here Yang et al. show that NCP is a dual-targeted protein that promotes phytochrome B localization to photobodies in the nucleus while facilitating PEP polymerase assembly in the plastids.
- Emily J. Yang
- , Chan Yul Yoo
- & Meng Chen
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Article
| Open AccessPhytochrome activates the plastid-encoded RNA polymerase for chloroplast biogenesis via nucleus-to-plastid signaling
Light initiates chloroplast biogenesis by controlling gene expression in plastids. Here Yoo et al. show that nuclear phytochrome signaling triggers plastid gene expression via a novel dual-localized protein necessary for nuclear phytochrome signaling and subsequent anterograde signaling to the plastid.
- Chan Yul Yoo
- , Elise K. Pasoreck
- & Meng Chen
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Article
| Open AccessSingle-molecule trapping and spectroscopy reveals photophysical heterogeneity of phycobilisomes quenched by Orange Carotenoid Protein
Upon photoactivation the Orange Carotenoid Protein (OCP) binds to the phycobilisome and prevents damage by thermally dissipating excess energy. Here authors use an Anti-Brownian ELectrokinetic trap to determine the photophysics of single OCP-quenched phycobilisomes and observe two distinct OCP-quenched states with either one or two OCPs bound.
- Allison H. Squires
- , Peter D. Dahlberg
- & W. E. Moerner
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Article
| Open AccessDaytime temperature is sensed by phytochrome B in Arabidopsis through a transcriptional activator HEMERA
The phyB photoreceptor senses nighttime temperature in Arabidopsis plants cultivated in short-day photoperiods. Here the authors show that phyB can also promote thermomorphogenesis during constant light or the daytime, and acts via a HEMERA-dependent mechanism that promotes the activity and accumulation of PIF4.
- Yongjian Qiu
- , Meina Li
- & Meng Chen
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Article
| Open AccessOCP–FRP protein complex topologies suggest a mechanism for controlling high light tolerance in cyanobacteria
Cyanobacterial photoprotection is controlled by OCP and FRP proteins, but their dynamic interplay is not fully understood. Here, the authors combine protein engineering, disulfide trapping and structural analyses to provide mechanistic insights into the transient OCP-FRP interaction.
- Nikolai N. Sluchanko
- , Yury B. Slonimskiy
- & Eugene G. Maksimov
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Article
| Open AccessA phosphorylation switch turns a positive regulator of phototropism into an inhibitor of the process
Light conditions modify plant growth and development via photoreceptors such as phototropins. Here the authors show that while phot1 promotes phototropism under low light, it can act to suppress phototropism in high-light environments through phosphorylation of PKS4.
- Paolo Schumacher
- , Emilie Demarsy
- & Christian Fankhauser
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Article
| Open AccessRedox regulation of PEP activity during seedling establishment in Arabidopsis thaliana
The plastid-encoded RNA polymerase PEP is regulated according to plastid redox state. Here, the authors show that the redox-regulated PRIN2 protein is reduced to monomeric form in a thiol-dependent manner in response to light and that PRIN2 monomers are required for PEP activity and retrograde signaling.
- Manuel Guinea Díaz
- , Tamara Hernández-Verdeja
- & Åsa Strand
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Article
| Open AccessThe F-box protein FKF1 inhibits dimerization of COP1 in the control of photoperiodic flowering
CONSTANS promotes flowering under long-day conditions in Arabidopsis but is rapidly degraded in short-day conditions. Here the authors show that the blue-light photoreceptor FKF1 can interact with the E3 ligase COP1 in a light-dependent manner and prevent degradation of CO in long-day conditions.
- Byoung-Doo Lee
- , Mi Ri Kim
- & Nam-Chon Paek
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Article
| Open AccessDecision-making in plants under competition
Plants may respond to light competition by growing upwards, via physiological changes that maximise performance under low light, or by growing laterally. Here Gruntman et al. show that the light-competition scenario determines the strategy employed by the clonal plant Potentilla reptans.
- Michal Gruntman
- , Dorothee Groß
- & Katja Tielbörger
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Article
| Open AccessPCH1 and PCHL promote photomorphogenesis in plants by controlling phytochrome B dark reversion
Dark reversion of the red-light receptor phytochrome B (phyB) converts the receptor to the inactive state. Here, Enderle et al. show that PCH1 and PCHL bind phyB and suppress dark reversion, and that far-red and blue-light induced upregulation of PCH1 and PCHL increases red light sensitivity in Arabidopsis.
- Beatrix Enderle
- , David J. Sheerin
- & Andreas Hiltbrunner
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Article
| Open AccessDifferent carotenoid conformations have distinct functions in light-harvesting regulation in plants
Carotenoids can dissipate excess energy captured by photosynthetic light-harvesting complexes to prevent photodamage. Here, via spectroscopic and in silico approaches, Liguori et al. resolve different carotenoid dark states and propose conformational changes that permit them to act as either energy donors or quenchers.
- Nicoletta Liguori
- , Pengqi Xu
- & Roberta Croce
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Article
| Open AccessMechanism of early light signaling by the carboxy-terminal output module of Arabidopsis phytochrome B
Plant phytochromes mediate the degradation of PIF transcription factors to transduce light signaling. Here, contrary to previous models, Qiu et al. show that degradation of PIF3 does not require the N-terminal photosensory module of PHYB but can instead be mediated by the C-terminal output module.
- Yongjian Qiu
- , Elise K. Pasoreck
- & Meng Chen
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Article
| Open AccessBlue light and CO2 signals converge to regulate light-induced stomatal opening
Stomata open in response to low CO2 conditions in the light to maximise photosynthesis. Here, Hiyama et al. identify two kinases that promote stomatal opening by inhibiting S-type anion channels downstream of phototropin and HT1 thereby acting as a convergence point for blue light and CO2 signaling.
- Asami Hiyama
- , Atsushi Takemiya
- & Ken-ichiro Shimazaki
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Article
| Open AccessPhytochrome-interacting factors directly suppress MIR156 expression to enhance shade-avoidance syndrome in Arabidopsis
Plants employ developmental strategies to avoid shade and compete with neighbors for light. Here, Xie et al. show that phytochrome-interacting factors, which are regulated in a light-dependent manner, directly repress MIR156 genes and promote the expression of SPL genes to enhance shade-avoidance responses.
- Yurong Xie
- , Yang Liu
- & Haiyang Wang
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Article
| Open AccessPhotosynthesis-dependent H2O2 transfer from chloroplasts to nuclei provides a high-light signalling mechanism
Multiple plastid-derived signals have been proposed but not shown to move to the nucleus to promote plant acclimation to fluctuating light. Here the authors use a fluorescent hydrogen peroxide sensor to provide evidence that H2O2 is transferred directly from chloroplasts to nuclei to control nuclear gene expression.
- Marino Exposito-Rodriguez
- , Pierre Philippe Laissue
- & Philip M. Mullineaux
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Article
| Open AccessMolecular basis for blue light-dependent phosphorylation of Arabidopsis cryptochrome 2
Plant cryptochromes are regulated by blue-light dependent phosphorylation. Here the authors map thein vivo phosphorylation sites of Arabidopsiscryptochrome 2 and identify four closely related kinases that act to both activate and destabilize the receptor in response to blue light.
- Qing Liu
- , Qin Wang
- & Chentao Lin
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Article
| Open AccessPPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3
Phytochrome photoreceptors mediate degradation of PIF transcription factors in the nucleus in response to light. Here Niet al. identify a family of nuclear protein kinases that interact with photoactivated phytochrome B and facilitate phytochrome-induced phosphorylation and degradation of PIF3.
- Weimin Ni
- , Shou-Ling Xu
- & Peter H. Quail
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Article
| Open AccessUVR2 ensures transgenerational genome stability under simulated natural UV-B in Arabidopsis t haliana
As sessile organisms, plants are exposed to recurrent solar UV-B radiation that can induce DNA damage. Here, the authors characterize mutations that occur in Arabidopsisunder light regimes simulating natural UV-B exposure and find that the UVR2 photolyase is the major component required to maintain genome stability.
- Eva-Maria Willing
- , Thomas Piofczyk
- & Ales Pecinka
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Article
| Open AccessRewiring of jasmonate and phytochrome B signalling uncouples plant growth-defense tradeoffs
Plant immune responses are often associated with reduced growth. Here, the authors show that combining mutations in transcriptional repressors of the defense and light perception pathways can confer both robust growth and strong herbivore defense, demonstrating that growth-defense tradeoffs can be uncoupled.
- Marcelo L. Campos
- , Yuki Yoshida
- & Gregg A. Howe
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Article
| Open AccessPhytochrome B and REVEILLE1/2-mediated signalling controls seed dormancy and germination in Arabidopsis
Seed dormancy prevents germination under adverse environmental conditions. Here the authors show that the RVE1 and RVE2 transcription factors suppress biosynthesis of the germination-promoting hormone GA and act downstream of phytochrome signalling to promote dormancy and repress light-induced germination.
- Zhimin Jiang
- , Gang Xu
- & Rongcheng Lin
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Article
| Open AccessDELLA-mediated PIF degradation contributes to coordination of light and gibberellin signalling in Arabidopsis
Gibberellins (GA) negatively regulate light-mediated suppression of hypocotyl elongation in plants. Here, Li et al. show that GA-mediated destabilization of DELLA proteins promotes accumulation of the light-regulated PIF transcription factors thus contributing to the crosstalk between light and GA signalling.
- Kunlun Li
- , Renbo Yu
- & Xing Wang Deng
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Article
| Open AccessPhytochrome and retrograde signalling pathways converge to antagonistically regulate a light-induced transcriptional network
Retrograde signals from dysfunctional chloroplasts influence plant response to light. Here the authors show that the GUN1 retrograde signalling pathway acts antagonistically to the phytochrome-mediated red light perception pathway to control the expression of GLK1, a key transcriptional regulator of photomorphogenesis.
- Guiomar Martín
- , Pablo Leivar
- & Elena Monte
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Article |
The transcriptional regulator BBX24 impairs DELLA activity to promote shade avoidance in Arabidopsis thaliana
Plants respond to shade by elongating their stems to grow toward the light. Here, Crocco et al. show that the BBX24 transcriptional regulator promotes the shade avoidance response by activating gibberellin signalling and the PIF4 transcription factor under low light conditions.
- Carlos D. Crocco
- , Antonella Locascio
- & Javier F. Botto
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Article
| Open AccessArabidopsis cell expansion is controlled by a photothermal switch
Light and temperature interact to control hypocotyl elongation in Arabidopsis. Here, Johansson et al.use experimental data and mathematical modelling to describe a photothermal molecular switch where temperature governs whether light represses or activates elongation.
- Henrik Johansson
- , Harriet J. Jones
- & Karen J. Halliday
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Article |
Light-regulated gene repositioning in Arabidopsis
Light induces the expression of many plant genes including chlorophyll a/b-binding proteins—CABs—but whether this occurs via altered genomic organization is unknown. Here, Feng et al. use a rolling-circle amplification model to show that CABgenes undergo nuclear repositioning in response to light.
- Chun-Miao Feng
- , Yongjian Qiu
- & Meng Chen
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Article |
Mechanism of signal transduction of the LOV2-Jα photosensor from Avena sativa
Fusion proteins containing blue-light-activated domains have been used as molecular switches to investigate cell signalling, but molecular understanding of the transduction pathway is lacking. Here, MD simulations are used to elucidate the transduction mechanism in a light oxygen voltage2-Ja photosensor.
- Emanuel Peter
- , Bernhard Dick
- & Stephan A. Baeurle