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1.
Nat Commun ; 12(1): 5614, 2021 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-34556672

RESUMO

Photoactivated phytochrome B (PHYB) binds to antagonistically acting PHYTOCHROME-INTERACTING transcription FACTORs (PIFs) to regulate hundreds of light responsive genes in Arabidopsis by promoting PIF degradation. However, whether PHYB directly controls the transactivation activity of PIFs remains ambiguous. Here we show that the prototypic PIF, PIF3, possesses a p53-like transcription activation domain (AD) consisting of a hydrophobic activator motif flanked by acidic residues. A PIF3mAD mutant, in which the activator motif is replaced with alanines, fails to activate PIF3 target genes in Arabidopsis, validating the functions of the PIF3 AD in vivo. Intriguingly, the N-terminal photosensory module of PHYB binds immediately adjacent to the PIF3 AD to repress PIF3's transactivation activity, demonstrating a novel PHYB signaling mechanism through direct interference of the transactivation activity of PIF3. Our findings indicate that PHYB, likely also PHYA, controls the stability and activity of PIFs via structurally separable dual signaling mechanisms.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fitocromo B/genética , Ativação Transcricional/genética , Proteína Supressora de Tumor p53/genética , Sequência de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Sítios de Ligação/genética , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Modelos Genéticos , Fitocromo A/genética , Fitocromo A/metabolismo , Fitocromo B/metabolismo , Plantas Geneticamente Modificadas , Ligação Proteica/efeitos da radiação , Homologia de Sequência de Aminoácidos , Ativação Transcricional/efeitos da radiação , Proteína Supressora de Tumor p53/metabolismo
2.
BMC Plant Biol ; 21(1): 401, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34461825

RESUMO

BACKGROUND: Timing is everything when it comes to the fitness outcome of a plant's ecological interactions, and accurate timing is particularly relevant for interactions with herbivores or mutualists that are based on ephemeral emissions of volatile organic compounds. Previous studies of the wild tobacco N. attenuata have found associations between the diurnal timing of volatile emissions, and daytime predation of herbivores by their natural enemies. RESULTS: Here, we investigated the role of light in regulating two biosynthetic groups of volatiles, terpenoids and green leaf volatiles (GLVs), which dominate the herbivore-induced bouquet of N. attenuata. Light deprivation strongly suppressed terpenoid emissions while enhancing GLV emissions, albeit with a time lag. Silencing the expression of photoreceptor genes did not alter terpenoid emission rhythms, but silencing expression of the phytochrome gene, NaPhyB1, disordered the emission of the GLV (Z)-3-hexenyl acetate. External abscisic acid (ABA) treatments increased stomatal resistance, but did not truncate the emission of terpenoid volatiles (recovered in the headspace). However, ABA treatment enhanced GLV emissions and leaf internal pools (recovered from tissue), and reduced internal linalool pools. In contrast to the pattern of diurnal terpenoid emissions and nocturnal GLV emissions, transcripts of herbivore-induced plant volatile (HIPV) biosynthetic genes peaked during the day. The promotor regions of these genes were populated with various cis-acting regulatory elements involved in light-, stress-, phytohormone- and circadian regulation. CONCLUSIONS: This research provides insights into the complexity of the mechanisms involved in the regulation of HIPV bouquets, a mechanistic complexity which rivals the functional complexity of HIPVs, which includes repelling herbivores, calling for body guards, and attracting pollinators.


Assuntos
Ritmo Circadiano , Herbivoria/fisiologia , Luz , Tabaco/fisiologia , Compostos Orgânicos Voláteis/metabolismo , Ácido Abscísico/farmacologia , Animais , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/fisiologia , Larva/fisiologia , Mariposas/fisiologia , Fitocromo B/genética , Fitocromo B/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Terpenos/metabolismo
3.
Nat Plants ; 7(9): 1213-1219, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34354260

RESUMO

To compensate for a sessile nature, plants have developed sophisticated mechanisms to sense varying environmental conditions. Phytochromes (phys) are light and temperature sensors that regulate downstream genes to render plants responsive to environmental stimuli1-4. Here, we show that phyB directly triggers the formation of a repressive chromatin loop by physically interacting with VERNALIZATION INSENSITIVE 3-LIKE1/VERNALIZATION 5 (VIL1/VRN5), a component of Polycomb Repressive Complex 2 (PRC2)5,6, in a light-dependent manner. VIL1 and phyB cooperatively contribute to the repression of growth-promoting genes through the enrichment of Histone H3 Lys27 trimethylation (H3K27me3), a repressive histone modification. In addition, phyB and VIL1 mediate the formation of a chromatin loop to facilitate the repression of ATHB2. Our findings show that phyB directly utilizes chromatin remodelling to regulate the expression of target genes in a light-dependent manner.


Assuntos
Aclimatação/genética , Adaptação Ocular/genética , Montagem e Desmontagem da Cromatina/genética , Proteínas de Homeodomínio/metabolismo , Fitocromo B/metabolismo , Proteínas do Grupo Polycomb/metabolismo , Estresse Fisiológico/genética , Arabidopsis/genética , Montagem e Desmontagem da Cromatina/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Proteínas de Homeodomínio/genética , Mutação , Dedos de Zinco PHD/genética , Dedos de Zinco PHD/fisiologia , Fitocromo B/genética , Proteínas do Grupo Polycomb/genética , Estresse Fisiológico/fisiologia
4.
New Phytol ; 232(3): 1201-1211, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34289130

RESUMO

Plants monitor their surrounding ambient light environment by specialized photoreceptor proteins. Among them, phytochromes monitor red and far-red light. These molecules perceive photons, undergo a conformational change, and regulate diverse light signaling pathways, resulting in the mediation of key developmental and growth responses throughout the whole life of plants. Posttranslational modifications of the photoreceptors and their signaling partners may modify their function. For example, the regulatory role of phosphorylation has been investigated for decades by using different methodological approaches. In the past few years, a set of studies revealed that ubiquitin-like short protein molecules, called small ubiquitin-like modifiers (SUMOs) are attached reversibly to different members of phytochrome signaling pathways, including phytochrome B, the dominant receptor of red light signaling. Furthermore, SUMO attachment modifies the action of the target proteins, leading to altered light signaling and photomorphogenesis. This review summarizes recent results regarding SUMOylation of various target proteins, the regulation of their SUMOylation level, and the physiological consequences of SUMO attachment. Potential future research directions are also discussed.


Assuntos
Proteínas de Arabidopsis , Fitocromo , Proteínas de Arabidopsis/metabolismo , Luz , Transdução de Sinal Luminoso , Fitocromo/metabolismo , Fitocromo B/metabolismo , Transdução de Sinais , Sumoilação
5.
Biochim Biophys Acta Bioenerg ; 1862(8): 148445, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-33940040

RESUMO

The effects of high-intensity light (HIL, 4 and 24 h) and UV-B (1 h) on the net photosynthesis rate, activity of photosystem II (PSII), content of photosynthetic pigments, anthocyanin and UV-absorbing pigments as well as the expression of certain light-responsive genes (HY5,CAB1) chalcone synthase (CHS) and main antioxidants enzyme genes (APX1, GPX and GR) in the leaves of phyB and phyA mutant A. thaliana plants were studied. Both UV-B and 4 and 24 h HIL decreased the PSII maximum quantum yield (Fv/Fm), PSII performance index (PIABS), photosynthesis and respiration rates in plants. Moreover, all stress treatments increased the dissipation of the absorbed energy (DI0/RC) as well as the flux of absorbed energy per RC (ABS/RC). The maximal changes in photosynthesis and chlorophyll fluorescence parameters were observed in the phyB mutant. The WT and the phyA mutant showed similar responses. In addition, the phyB mutant exhibited decreases in the expression of genes encoding enzyme CHS, the transcription factor HY5 and the antioxidant enzymes APX1 and GPX. One of the possible mechanisms protecting the photosynthetic apparatus from light excess or UV radiation is the elevated content of various pigments that can act as antioxidants or optical filters. We assume that the greater decrease in photosynthetic activity in the phyB mutant under HIL and UV-B conditions was due to the decreased content of carotenoids and UV-absorbing pigments in this mutant.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Fotossíntese , Folhas de Planta/metabolismo , Raios Ultravioleta , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Luz , Fitocromo A/genética , Fitocromo A/metabolismo , Fitocromo B/genética , Fitocromo B/metabolismo , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/efeitos da radiação
6.
J Integr Plant Biol ; 63(6): 1133-1146, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33982818

RESUMO

Light serves as a crucial environmental cue which modulates plant growth and development, and which is controlled by multiple photoreceptors including the primary red light photoreceptor, phytochrome B (phyB). The signaling mechanism of phyB involves direct interactions with a group of basic helix-loop-helix (bHLH) transcription factors, PHYTOCHROME-INTERACTING FACTORS (PIFs), and the negative regulators of photomorphogenesis, COP1 and SPAs. H2A.Z is an evolutionarily conserved H2A variant which plays essential roles in transcriptional regulation. The replacement of H2A with H2A.Z is catalyzed by the SWR1 complex. Here, we show that the Pfr form of phyB physically interacts with the SWR1 complex subunits SWC6 and ARP6. phyB and ARP6 co-regulate numerous genes in the same direction, some of which are associated with auxin biosynthesis and response including YUC9, which encodes a rate-limiting enzyme in the tryptophan-dependent auxin biosynthesis pathway. Moreover, phyB and HY5/HYH act to inhibit hypocotyl elongation partially through repression of auxin biosynthesis. Based on our findings and previous studies, we propose that phyB promotes H2A.Z deposition at YUC9 to inhibit its expression through direct phyB-SWC6/ARP6 interactions, leading to repression of auxin biosynthesis, and thus inhibition of hypocotyl elongation in red light.


Assuntos
Proteínas de Arabidopsis/isolamento & purificação , Arabidopsis/metabolismo , Luz , Fitocromo B/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Hipocótilo/metabolismo , Hipocótilo/efeitos da radiação
7.
EMBO Rep ; 22(7): e51944, 2021 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-34018302

RESUMO

Iron (Fe) deficiency affects global crop productivity and human health. However, the role of light signaling in plant Fe uptake remains uncharacterized. Here, we find that light-induced Fe uptake in tomato (Solanum lycopersicum L.) is largely dependent on phytochrome B (phyB). Light induces the phyB-dependent accumulation of ELONGATED HYPOCOTYL 5 (HY5) protein both in the leaves and roots. HY5 movement from shoots to roots activates the expression of FER transcription factor, leading to the accumulation of transcripts involved in Fe uptake. Mutation in FER abolishes the light quality-induced changes in Fe uptake. The low Fe uptake observed in phyB, hy5, and fer mutants is accompanied by lower photosynthetic electron transport rates. Exposure to red light at night increases Fe accumulation in wild-type fruit but has little effects on fruit of phyB mutants. Taken together, these results demonstrate that Fe uptake is systemically regulated by light in a phyB-HY5-FER-dependent manner. These findings provide new insights how the manipulation of light quality could be used to improve Fe uptake and hence the nutritional quality of crops.


Assuntos
Proteínas de Arabidopsis , Fitocromo B , Proteínas de Arabidopsis/biossíntese , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/biossíntese , Fatores de Transcrição de Zíper de Leucina Básica/genética , Regulação da Expressão Gênica de Plantas , Hipocótilo/metabolismo , Ferro , Mutação , Fosfotransferases/biossíntese , Fosfotransferases/genética , Fitocromo B/genética , Fitocromo B/metabolismo , Fatores de Transcrição/genética
8.
Sci Rep ; 11(1): 7540, 2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33824368

RESUMO

In plants, during growth and development, photoreceptors monitor fluctuations in their environment and adjust their metabolism as a strategy of surveillance. Phytochromes (Phys) play an essential role in plant growth and development, from germination to fruit development. FR-light (FR) insensitive mutant (fri) carries a recessive mutation in Phytochrome A and is characterized by the failure to de-etiolate in continuous FR. Here we used iTRAQ-based quantitative proteomics along with metabolomics to unravel the role of Phytochrome A in regulating central metabolism in tomato seedlings grown under FR. Our results indicate that Phytochrome A has a predominant role in FR-mediated establishment of the mature seedling proteome. Further, we observed temporal regulation in the expression of several of the late response proteins associated with central metabolism. The proteomics investigations identified a decreased abundance of enzymes involved in photosynthesis and carbon fixation in the mutant. Profound accumulation of storage proteins in the mutant ascertained the possible conversion of sugars into storage material instead of being used or the retention of an earlier profile associated with the mature embryo. The enhanced accumulation of organic sugars in the seedlings indicates the absence of photomorphogenesis in the mutant.


Assuntos
Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Fitocromo A/fisiologia , Cotilédone/metabolismo , Expressão Gênica/genética , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/genética , Luz , Lycopersicon esculentum/crescimento & desenvolvimento , Metabolômica/métodos , Células Fotorreceptoras/metabolismo , Fotossíntese , Fitocromo/genética , Fitocromo/fisiologia , Fitocromo A/genética , Fitocromo B/metabolismo , Proteoma/genética , Proteoma/metabolismo , Proteômica/métodos , Plântula/genética , Plântula/crescimento & desenvolvimento , Transcriptoma/genética
9.
Plant Cell ; 33(6): 1961-1979, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-33768238

RESUMO

Light is a key environmental cue that fundamentally regulates plant growth and development, which is mediated by the multiple photoreceptors including the blue light (BL) photoreceptor cryptochrome 1 (CRY1). The signaling mechanism of Arabidopsis thaliana CRY1 involves direct interactions with CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1)/SUPPRESSOR OF PHYA-105 1 and stabilization of COP1 substrate ELONGATED HYPOCOTYL 5 (HY5). H2A.Z is an evolutionarily conserved histone variant, which plays a critical role in transcriptional regulation through its deposition in chromatin catalyzed by SWR1 complex. Here we show that CRY1 physically interacts with SWC6 and ARP6, the SWR1 complex core subunits that are essential for mediating H2A.Z deposition, in a BL-dependent manner, and that BL-activated CRY1 enhances the interaction of SWC6 with ARP6. Moreover, HY5 physically interacts with SWC6 and ARP6 to direct the recruitment of SWR1 complex to HY5 target loci. Based on previous studies and our findings, we propose that CRY1 promotes H2A.Z deposition to regulate HY5 target gene expression and photomorphogenesis in BL through the enhancement of both SWR1 complex activity and HY5 recruitment of SWR1 complex to HY5 target loci, which is likely mediated by interactions of CRY1 with SWC6 and ARP6, and CRY1 stabilization of HY5, respectively.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas Cromossômicas não Histona/metabolismo , Criptocromos/metabolismo , Histonas/metabolismo , Arabidopsis/citologia , Proteínas de Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Clorofila/biossíntese , Clorofila/metabolismo , Proteínas Cromossômicas não Histona/genética , Criptocromos/genética , Regulação da Expressão Gênica de Plantas , Histonas/genética , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/metabolismo , Luz , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Fitocromo A/genética , Fitocromo A/metabolismo , Fitocromo B/genética , Fitocromo B/metabolismo , Plantas Geneticamente Modificadas , Mapas de Interação de Proteínas , Tabaco/genética , Tabaco/metabolismo
10.
Trends Plant Sci ; 26(5): 509-523, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33461868

RESUMO

Major strides have been made over the past decade in elucidating the mechanisms that mediate shade-avoidance responses. The canonical PHYTOCHROME INTERACTING FACTOR (PIF)-auxin pathway that begins with inactivation of phytochrome B (phyB) by a low red:far-red (R:FR) ratio, and that leads to increased elongation, has been thoroughly characterized in arabidopsis (Arabidopsisthaliana) seedlings. Nevertheless, studies in other life stages and plant species have demonstrated the role of other wavelengths, photoreceptors, and hormones in the orchestration of shade-avoidance responses. We highlight recent developments that illustrate how canopy light cues regulate signaling through auxin, gibberellins (GAs), jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), and strigolactones (SLs) to modulate key aspects of plant growth, metabolism, and defense.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fitocromo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Hormônios , Luz , Fitocromo/metabolismo , Fitocromo B/metabolismo
11.
Plant J ; 105(1): 22-33, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33098600

RESUMO

Plants experience temperature fluctuations during the course of the daily cycle, and although stem growth responds rapidly to these changes we largely ignore whether there is a short-term memory of previous conditions. Here we show that nighttime temperatures affect the growth of the hypocotyl of Arabidopsis thaliana seedlings not only during the night but also during the subsequent photoperiod. Active phytochrome B (phyB) represses nighttime growth and warm temperatures reduce active phyB via thermal reversion. The function of PHOTOPERIODIC CONTROL OF HYPOCOTYL1 (PCH1) is to stabilise active phyB in nuclear bodies but, surprisingly, warmth reduces PCH1 gene expression and PCH1 stability. When phyB was active at the beginning of the night, warm night temperatures enhanced the levels of nuclear phyB and reduced hypocotyl growth rate during the following day. However, when end-of-day far-red light minimised phyB activity, warm night temperatures reduced the levels of nuclear phyB and enhanced the hypocotyl growth rate during the following day. This complex growth pattern was absent in the phyB mutant. We propose that temperature-induced changes in the levels of PCH1 and in the size of the physiologically relevant nuclear pool of phyB amplify the impact of phyB-mediated temperature sensing.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Metalochaperonas/metabolismo , Fitocromo B/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Metalochaperonas/fisiologia , Fotoperíodo , Fitocromo B/fisiologia , Plântula/metabolismo , Plântula/fisiologia , Temperatura
12.
New Phytol ; 229(4): 2050-2061, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33078389

RESUMO

In Arabidopsis thaliana, phytochrome B (phyB) is the dominant receptor of photomorphogenic development under red light. Phytochrome B interacts with a set of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR 3 (PIF3). The interaction between PIF3 and photoactivated phyB leads to the rapid phosphorylation and degradation of PIF3 and also to the degradation of phyB, events which are required for proper photomorphogenesis. Here we report that PIF3 is SUMOylated at the Lys13 (K13) residue and that we could detect this posttranslational modification in a heterologous experimental system and also in planta. We also found that the SUMO acceptor site mutant PIF3(K13R) binds more strongly to the target promoters than its SUMOylated, wild-type counterpart. Seedlings expressing PIF3(K13R) show an elongated hypocotyl response, elevated photoprotection and higher transcriptional induction of red-light responsive genes compared with plantlets expressing wild-type PIF3. These observations are supported by the lower level of phyB in plants which possess only PIF3(K13R), indicating that SUMOylation of PIF3 also alters photomorphogenesis via the regulation of phyB levels. In conclusion, whereas SUMOylation is generally connected to different stress responses, it also fine-tunes light signalling by reducing the biological activity of PIF3, thus promoting photomorphogenesis.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Fitocromo B , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Luz , Fitocromo B/genética , Fitocromo B/metabolismo , Sumoilação
13.
Plant J ; 105(6): 1689-1702, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33354819

RESUMO

Adventitious roots (ARs) are an important root type for plants and display a high phenotypic plasticity in response to different environmental stimuli. Previous studies found that dark-light transition can trigger AR formation from the hypocotyl of etiolated Arabidopsis thaliana, which was used as a model for the identification of regulators of AR biogenesis. However, the central regulatory machinery for darkness-induced hypocotyl AR (HAR) remains elusive. Here, we report that photoreceptors suppress HAR biogenesis through regulating the molecular module essential for lateral roots. We found that hypocotyls embedded in soil or in continuous darkness are able to develop HARs, wherein photoreceptors act as negative regulators. Distinct from wound-induced ARs that require WOX11 and WOX12, darkness-induced HARs are fully dependent on ARF7, ARF19, WOX5/7, and LBD16. Further studies established that PHYB interacts with IAA14, ARF7, and ARF9. The interactions stabilize IAA14 and inhibit the transcriptional activities of ARF7 and ARF19 and thus suppress biogenesis of darkness-induced HARs. This finding not only revealed the central machinery controlling HAR biogenesis but also illustrated that AR formation could be initiated by multiple pathways.


Assuntos
Proteínas de Arabidopsis/metabolismo , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/metabolismo , Fitocromo B/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Escuridão , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética
14.
Plant Physiol ; 184(3): 1563-1572, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32913044

RESUMO

Perception of a change in light intensity leads to the activation of multiple physiological, metabolic, and molecular responses in plants. These responses allow acclimation to fluctuating light conditions, e.g. sunflecks in field grown plants, preventing cellular damage associated with excess light stress. Perception of light stress by a single Arabidopsis (Arabidopsis thaliana) leaf was recently shown to activate different local and systemic responses that include rapid changes in stomatal aperture size; these were found to be coordinated by a systemic process of reactive oxygen species (ROS)-derived ROS production (i.e. the ROS wave). How light intensity is perceived, and how long the ROS wave stays "on" during this process are, however, unknown. Here we show that triggering of the ROS wave by a local excess light stress treatment results in the induction and maintenance of high levels of systemic ROS for up to 6 h. Despite these high systemic ROS levels, stomatal aperture size returns to control size within 3 h, and the systemic stomatal response can be retriggered within 6 h. These findings suggest that the ROS wave triggers a systemic stress memory mechanism that lasts for 3 to 6 h, but that within 3 h of its activation, stomata become insensitive to ROS and open. We further show that the excess light stress-triggered ROS wave, as well as the excess light stress-triggered local and systemic stomatal aperture closure responses, are dependent on phytochrome B function. Our findings reveal a delicate interplay between excess light stress, phytochrome B, ROS production, and rapid systemic stomatal responses.


Assuntos
Aclimatação/efeitos dos fármacos , Arabidopsis/metabolismo , Luz , Fitocromo B/metabolismo , Folhas de Planta/metabolismo , Estômatos de Plantas/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Variação Genética , Genótipo , Mutação
15.
Development ; 147(19)2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-32994167

RESUMO

High ambient temperature attributable to global warming has a profound influence on plant growth and development at all stages of the life cycle. The response of plants to high ambient temperature, termed thermomorphogenesis, is characterized by hypocotyl and petiole elongation and hyponastic growth at the seedling stage. However, our understanding of the molecular mechanism of thermomorphogenesis is still rudimentary. Here, we show that a set of four SUPPRESSOR OF PHYA-105 (SPA) genes is required for thermomorphogenesis. Consistently, SPAs are necessary for global changes in gene expression in response to high ambient temperature. In the spaQ mutant at high ambient temperature, the level of SPA1 is unaffected, whereas the thermosensor phytochrome B (phyB) is stabilized. Furthermore, in the absence of four SPA genes, the pivotal transcription factor PIF4 fails to accumulate, indicating a role of SPAs in regulating the phyB-PIF4 module at high ambient temperature. SPA1 directly phosphorylates PIF4 in vitro, and a mutant SPA1 affecting the kinase activity fails to rescue the PIF4 level in addition to the thermo-insensitive phenotype of spaQ, suggesting that the SPA1 kinase activity is necessary for thermomorphogenesis. Taken together, these data suggest that SPAs are new components that integrate light and temperature signaling by fine-tuning the phyB-PIF4 module.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fitocromo B/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Ontologia Genética , Fitocromo B/genética , Temperatura
16.
Plant J ; 104(4): 1038-1053, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32890447

RESUMO

Phytochromes are red/far-red light receptors in plants involved in the regulation of growth and development. Phytochromes can sense the light environment and contribute to measuring day length; thereby, they allow plants to respond and adapt to changes in the ambient environment. Two well-characterized signalling pathways act downstream of phytochromes and link light perception to the regulation of gene expression. The CONSTITUTIVELY PHOTOMORPHOGENIC 1/SUPPRESSOR OF PHYA-105 (COP1/SPA) E3 ubiquitin ligase complex and the PHYTOCHROME INTERACTING FACTORs (PIFs) are key components of these pathways and repress light responses in the dark. In light-grown seedlings, phytochromes inhibit COP1/SPA and PIF activity and thereby promote light signalling. In a yeast-two-hybrid screen for proteins binding to light-activated phytochromes, we identified COLD-REGULATED GENE 27 (COR27). COR27 and its homologue COR28 bind to phyA and phyB, the two primary phytochromes in seed plants. COR27 and COR28 have been described previously with regard to a function in the regulation of freezing tolerance, flowering and the circadian clock. Here, we show that COR27 and COR28 repress early seedling development in blue, far-red and in particular red light. COR27 and COR28 contain a conserved Val-Pro (VP)-peptide motif, which mediates binding to the COP1/SPA complex. COR27 and COR28 are targeted for degradation by COP1/SPA and mutant versions with a VP to AA amino acid substitution in the VP-peptide motif are stabilized. Overall, our data suggest that COR27 and COR28 accumulate in light but act as negative regulators of light signalling during early seedling development, thereby preventing an exaggerated response to light.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Transdução de Sinal Luminoso , Fitocromo B/metabolismo , Proteínas Repressoras/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Relógios Circadianos , Mutação , Complexo de Endopeptidases do Proteassoma , Proteólise , Proteínas Repressoras/genética , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Ubiquitina-Proteína Ligases/genética
17.
ACS Synth Biol ; 9(9): 2291-2300, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32786352

RESUMO

Multiobjective optimization of microbial chassis for the production of xenobiotic compounds requires the implementation of metabolic control strategies that permit dynamic distribution of cellular resources between biomass and product formation. We addressed this need in a previous study by engineering the T7 RNA polymerase to be thermally responsive. The modified polymerase is activated only after the temperature of the host cell falls below 18 °C, and Escherichia coli cells that employ the protein to transcribe the heterologous lycopene biosynthetic pathway exhibit impressive improvements in productivity. We have expanded our toolbox of metabolic switches in the current study by engineering a version of the T7 RNA polymerase that drives the transition between biomass and product formation upon stimulation with red light. The engineered polymerase is expressed as two distinct polypeptide chains. Each chain comprises one of two photoactive components from Arabidopsis thaliana, phytochrome B (PhyB) and phytochrome-integrating factor 3 (PIF3), as well as the N- or C-terminus domains of both, the vacuolar ATPase subunit (VMA) intein of Saccharomyces cerevisiae and the polymerase. Red light drives photodimerization of PhyB and PIF3, which then brings together the N- and C-terminus domains of the VMA intein. Trans-splicing of the intein follows suit and produces an active form of the polymerase that subsequently transcribes any sequence that is under the control of a T7 promoter. The photodimerization also involves a third element, the cyanobacterial chromophore phycocyanobilin (PCB), which too is expressed heterologously by E. coli. We deployed this version of the T7 RNA polymerase to control the production of lycopene in E. coli and observed tight control of pathway expression. We tested a variety of expression configurations to identify one that imposes the lowest metabolic burden on the strain, and we subsequently optimized key parameters such as the source, moment, and duration of photostimulation. We also identified targets for future refinement of the circuit. In summary, our work is a significant advance for the field and greatly expands on previous work by other groups that have used optogenetic circuits to control heterologous metabolism in prokaryotic hosts.


Assuntos
Escherichia coli/metabolismo , Luz , Optogenética/métodos , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Vias Biossintéticas/genética , RNA Polimerases Dirigidas por DNA/genética , Dimerização , Escherichia coli/genética , Engenharia Metabólica , Fitocromo B/genética , Fitocromo B/metabolismo , Plasmídeos/genética , Plasmídeos/metabolismo , ATPases Vacuolares Próton-Translocadoras/genética , ATPases Vacuolares Próton-Translocadoras/metabolismo , Proteínas Virais/genética
18.
Mol Cells ; 43(7): 645-661, 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32732458

RESUMO

Leaf senescence is a developmental process by which a plant actively remobilizes nutrients from aged and photosynthetically inefficient leaves to young growing ones by disassembling organelles and degrading macromolecules. Senescence is accelerated by age and environmental stresses such as prolonged darkness. Phytochrome B (phyB) inhibits leaf senescence by inhibiting phytochrome-interacting factor 4 (PIF4) and PIF5 in prolonged darkness. However, it remains unknown whether phyB mediates the temperature signal that regulates leaf senescence. We found the light-activated form of phyB (Pfr) remains active at least four days after a transfer to darkness at 20°C but is inactivated more rapidly at 28°C. This faster inactivation of Pfr further increases PIF4 protein levels at the higher ambient temperature. In addition, PIF4 mRNA levels rise faster after the transfer to darkness at high ambient temperature via a mechanism that depends on ELF3 but not phyB. Increased PIF4 protein then binds to the ORE1 promoter and activates its expression together with ABA and ethylene signaling, accelerating leaf senescence at high ambient temperature. Our results support a role for the phy-PIF signaling module in integrating not only light signaling but also temperature signaling in the regulation of leaf senescence.


Assuntos
Envelhecimento/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fitocromo B/metabolismo , Folhas de Planta/metabolismo , Ácido Abscísico/metabolismo , Envelhecimento/genética , Envelhecimento/efeitos da radiação , Arabidopsis/genética , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Imunoprecipitação da Cromatina , Escuridão , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Reguladores de Crescimento de Plantas/farmacologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Plantas Geneticamente Modificadas/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Transdução de Sinais/efeitos da radiação , Temperatura , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
19.
Plant Cell Environ ; 43(9): 2224-2238, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32542798

RESUMO

The ratio of red light to far-red light (R:FR) is perceived by phytochrome B (phyB) and informs plants of nearby competition. A low R:FR indicative of competition induces the shade avoidance syndrome and suppresses branching by incompletely understood mechanisms. Phytochrome interacting factors (PIFs) are transcription factors targeted by phytochromes to evoke photomorphogenic responses. PIF4 and PIF5 promote shade avoidance responses and become inactivated by direct interaction with active phyB in the nucleus. Here, genetic and physiological assays show that PIF4 and PIF5 contribute to the suppression of branching resulting from phyB loss of function and a low R:FR, although roles for other PIFs or pathways may exist. The suppression of branching is associated with PIF4/PIF5 promotion of the expression of the branching inhibitor BRANCHED 1 and abscisic acid (ABA) accumulation in axillary buds and is dependent on the function of the key ABA biosynthetic enzyme Nine-cis-epoxycarotenoid dioxygenase 3. However, PIF4/PIF5 function is not confined to a single hormonal pathway, as they also promote stem indole-3-acetic acid accumulation and stimulate systemic auxin signalling, which contribute to the suppression of bud growth when phyB is inactive.


Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ácidos Indolacéticos/metabolismo , Ácido Abscísico/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Dioxigenases/genética , Dioxigenases/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Luz , Fitocromo/metabolismo , Fitocromo B/genética , Fitocromo B/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Caules de Planta/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
20.
Plant Biotechnol J ; 18(12): 2520-2532, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32531863

RESUMO

Maize is a major staple crop widely used for food, feedstocks and industrial products. Shade-avoidance syndrome (SAS), which is triggered when plants sense competition of light from neighbouring vegetation, is detrimental for maize yield production under high-density planting conditions. Previous studies have shown that the red and far-red photoreceptor phytochromes are responsible for perceiving the shading signals and triggering SAS in Arabidopsis; however, their roles in maize are less clear. In this study, we examined the expression patterns of ZmPHYC1 and ZmPHYC2 and found that ZmPHYC1, but not ZmPHYC2, is highly expressed in leaves and is regulated by the circadian clock. Both ZmPHYC1 and ZmPHYC2 proteins are localized to both the nucleus and cytoplasm under light conditions and both of them can interact with themselves or with ZmPHYBs. Heterologous expression of ZmPHYCs can complement the Arabidopsis phyC-2 mutant under constant red light conditions and confer an attenuated SAS in Arabidopsis in response to shading. Double knockout mutants of ZmPHYC1 and ZmPHYC2 created using the CRISPR/Cas9 technology display a moderate early-flowering phenotype under long-day conditions, whereas ZmPHYC2 overexpression plants exhibit a moderately reduced plant height and ear height. Together, these results provided new insight into the function of ZmPHYCs and guidance for breeding high-density tolerant maize cultivars.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fitocromo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Sistemas CRISPR-Cas/genética , Regulação da Expressão Gênica de Plantas/genética , Fitocromo/genética , Fitocromo/metabolismo , Fitocromo B/metabolismo , Zea mays/genética , Zea mays/metabolismo
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