Phytochrome Pr Research Articles

Novel high-efficiency violet-red dual-emitting Lu2GeO5: Bi3+, Eu3+ phosphors for indoor plant growth lighting

A batch of Bi3+/Eu3+ co-doped Lu2GeO5 phosphors were synthesized by high-temperature solid-state reaction, and the corresponding X-ray diffraction, excitation and emission spectra, energy transfer (ET) mechanism, and temperature-dependent spectra of the Lu2GeO5: xBi3+, yEu3+ (abbreviated as LGO: xBi3+, yEu3+) phosphors were systematically studied. In LGO:xBi3+, yEu3+ phosphors, the Bi3+ and Eu3+ ions occupied the Lu3+ sites and they resulted in violet-red dual-emission bands in the 300–750 nm wavelength range under 313 nm excitation. The ET from Bi3+ to Eu3+ could be found in the as-prepared LGO: 3%Bi3+, yEu3+ samples, and the ET efficiency reach as high as 91% when y = 16%. The LGO: 3%Bi3+, 5%Eu3+ phosphors showed high quantum efficiency of 43% and good thermal stability (I423K/I303K = 51%). Importantly, the emission curve of the LGO: 3%Bi3+, 5%Eu3+ phosphors had important spectral overlap with the absorption spectrum of phytochrome PR, indicating that the LGO: Bi3+, Eu3+ phosphors had great prospect to be used in indoor plant growth lighting.

Forward Photodynamics of the Noncanonical Red/Green NpR3784 Cyanobacteriochrome from Nostoc punctiforme.

Cyanobacteriochromes (CBCRs) make up a diverse family of cyanobacterial photoreceptors distantly related to the phytochrome photoreceptors of land plants. At least two lineages of CBCRs have reacquired red-absorbing dark states similar to the phytochrome Pr resting state but are coupled to green-absorbing light-adapted states rather than the canonical far-red-absorbing light-adapted state. One such lineage includes the canonical red/green (R/G) CBCRs that includes AnPixJg2 (UniProtKB Q8YXY7 ) and NpR6012g4 (UniProtKB B2IU14 ) that have been extensively characterized. Here we examine the forward Pr photodynamics of NpR3784 (UniProtKB B2J457 ), a representative member of the second R/G CBCR subfamily. Using broadband transient absorption pump-probe spectroscopy, we characterize both primary (100 fs to 10 ns) and secondary (10 ns to 1 ms) forward (Pr → Pg) photodynamics and compare the results to temperature-jump cryokinetics measurements. Our studies show that primary isomerization dynamics occur on an ∼10 ps timescale, yet remarkably, the red-shifted primary Lumi-Rf photoproduct found in all photoactive canonical R/G CBCRs examined to date is extremely short-lived in NpR3784. These results demonstrate that differences in reaction pathways reflect the evolutionary history of R/G CBCRs despite the convergent evolution of their photocycle end products.

Luminescent properties of Zn2+-doped CaAl12O19:Mn4+ deep-red phosphor for indoor plant cultivation

A series of CaAl12O19: 0.5%Mn4+ phosphors doped with different concentrations of Zn2+ were prepared via solid state reaction process. The micrographs and phases of powders were analyzed by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. The Photoluminescence excitation spectra(PLE) and emission spectra(PL) of CaAl12O19: 0.5%Mn4+ with varying Zn2+ concentrations were investigated, the result indicated that prepared samples after Zn2+-doping exhibited deep red emission (658 nm) under the excitation of ultraviolet (UV), near ultraviolet (NUV). PL spectra indicated that Zn2+-doping could remarkably enhance the luminescent intensity of CaAl12O19:0.5%Mn4+. When the doping concentration of Zn2+ was 4%, the emission intensity of Ca0.96Zn0.04Al12O19:0.5%Mn4+ was improved up to 2.2 times that of pure CaAl12O19:0.5%Mn4+. In addition, the emission band of phosphor is highly compatible with the absorption band of phytochrome PR(660 nm). Besides, the internal quantum efficiency (IQE) was up to 67.1%. All the obtained results indicated that CaAl12O19:Zn2+, 0.5%Mn4+ has potential application value in indoor plant cultivation.

High concentration Eu3+-doped NaYb(MoO4)2 multifunctional material: Thermometer and plant growth lamp matching phytochrome PR

Phytochromes PR and PFR are distributed in various organs of plant, phytochrome PR absorbs red light and phytochrome PFR absorbs far-red light, respectively, so the flower induction, etc. can be controlled by changing the ratio of red light to far-red light. The emission of Eu3+ (transition from 5D0→7F2) is located at the red range and matches with the absorption band of PR. Herein, we synthesized successfully NaYb(MoO4)2: Eu3+ phosphors with the high doping concentration (50%) by hydrothermal method with further calcinations. The LED device was also fabricated by the blue InGaN chip combined with the red phosphors NaYb(MoO4)2: 50%Eu3+ based on the excellent luminescent intensity. Moreover, the effect of temperature on the excitation intensity ratio of MoO42− to Eu3+ has also been studied, which provided the possibility of simultaneous luminescence and temperature measurement. This work is the first time to use Eu3+ as a red source matching PR, and the red phosphors have potential value to control plant growth.

Active and silent chromophore isoforms for phytochrome Pr photoisomerization: An alternative evolutionary strategy to optimize photoreaction quantum yields.

Photoisomerization of a protein bound chromophore is the basis of light sensing of many photoreceptors. We tracked Z-to-E photoisomerization of Cph1 phytochrome chromophore PCB in the Pr form in real-time. Two different phycocyanobilin (PCB) ground state geometries with different ring D orientations have been identified. The pre-twisted and hydrogen bonded PCBa geometry exhibits a time constant of 30 ps and a quantum yield of photoproduct formation of 29%, about six times slower and ten times higher than that for the non-hydrogen bonded PCBb geometry. This new mechanism of pre-twisting the chromophore by protein-cofactor interaction optimizes yields of slow photoreactions and provides a scaffold for photoreceptor engineering.

Electronic transitions and heterogeneity of the bacteriophytochrome Pr absorption band: An angle balanced polarization resolved femtosecond VIS pump–IR probe study

Photoisomerization of biliverdin (BV) chromophore triggers the photoresponse in native Agp1 bacteriophytochrome. We discuss heterogeneity in phytochrome Pr form to account for the shape of the absorption profile. We investigated different regions of the absorption profile by angle balanced polarization resolved femtosecond VIS pump–IR probe spectroscopy. We studied the Pr form of Agp1 with its natural chromophore and with a sterically locked 18Et-BV (locked Agp1). We followed the dynamics and orientations of the carbonyl stretching vibrations of ring D and ring A in their ground and electronically excited states. Photoisomerization of ring D is reflected by strong signals of the ring D carbonyl vibration. In contrast, orientational data on ring A show no rotation of ring A upon photoexcitation. Orientational data allow excluding a ZZZasa geometry and corroborates a nontwisted ZZZssa geometry of the chromophore. We found no proof for heterogeneity but identified a new, to our knowledge, electronic transition in the absorption profile at 644 nm (S0→S2). Excitation of the S0→S2 transition will introduce a more complex photodynamics compared with S0→S1 transition. Our approach provides fundamental information on disentanglement of absorption profiles, identification of chromophore structures, and determination of molecular groups involved in the photoisomerization process of photoreceptors.

Solvatochromism of triarylbilindiones: far-red-absorbing bilindiones formed in aprotic amides and amines

Solvatochromism of triarylbilindiones was investigated to shed light on the mechanism and interactions involved in the phytochrome Pr–Pfr isomerisation. 1,19,21,24-Tetrahydro-5,10,15-tri(4-cyanophenyl)bilin-1,19-dione exhibited an electronic absorption maximum at 631 nm in toluene, while it exhibited the absorption maximum at 729 nm in N,N-dimethylformamide. A similar far-red-absorbing bilindione (Pfr) was formed in aprotic amides such as N,N-dimethylacetamide and 1-methylpyrrolidone, but was not formed in protic amides such as formamide and N-methylformamide. The Pfr was formed in the presence of a relatively high concentration (∼0.1 M) of amines such as butylamine, 1,2-ethanediamine and piperidine in methanol. The formation of Pfr in amides was inhibited by the addition of protic polar solvents, in particular hydrogen donor solvents such as 2,2,2-trifluoroethanol and methanol, while the formation of Pfr in the presence of amines was favourable in polar solvents. Tricyanophenyl bilindione tends to form Pfr than does tri(4-methoxyphenyl)bilindione. These observations suggest that the bilindiones act as hydrogen donors to form a hydrogen bond complex with amides or amines.

Light-Activated Phosphatase

Light influences many plant processes such as development, circadian responses including flowering, and growth. Plants are able to sense and to respond specifically to different wavelengths of light; red and far-red light are sensed by phytochromes, which are light-regulated serine and threonine kinases. Using a yeast two-hybrid screen, Kim et al. identified a protein phosphatase 2A catalytic subunit (from pea) that interacted with the Arabidopsis phytochrome A. The authors designated the phosphatase FyPP for flower-specific, phytochrome-associated protein phosphatase. In vitro, FyPP interacted with phytochrome A and B, with a preference for phytochrome B. When the phytochromes were pretreated with far-red light, they were designated Pfrs and FyPP had a preference for these. If Pfrs were not phosphorylated, they interacted more strongly with FyPP. Red light stimulates the translocation of phytochromes to the nucleus. Using a green-fluorescent protein fusion protein, the authors determined that FyPP was exclusively cytosolic. Thus, FyPP appears to interact specifically with the cytosolic Pfrs. In vitro phosphatase assays demonstrated that FyPP was able to dephosphorylate phytochrome A in the presence of Zn 2+ or Fe 2+ and that dephosphorylation occurred more quickly for the Pfr than for the red phytochrome (Pr). Overexpression of pea FyPP in Arabidopsis delayed flowering, whereas an antisense version produced plants that flowered earlier than wild-type plants. Thus, FyPP appears to be a negative regulator of the long-day flowering response. D.-H. Kim, J.-G. Kang, S.-S. Yang, K.-S. Chung, P.-S. Song, C.-M. Park, A phytochrome-associated protein phsophatase 2A modulates light signals in flowering time control in Arabidopsis . Plant Cell 14 , 3043-3056 (2002). [Abstract] [Full Text]

Excited-state properties of biliproteins: I. Phytochrome Pr

Phytochrome Pr has been investigated by means of picosecond intensity-dependent transmission measurements at several excitation wavelengths inside the S 0→S 1 absorption band. The experimental data exhibit relatively strong excited-state absorption (ESA) within the whole spectral range of the S 0→S 1 absorption, which is followed by fast relaxations on the femtosecond time scale (<200 fs). The ESA cross sections at wavelengths below 640 nm are lower than those of the ground-state absorption, but they are noticeably larger at the maximum and at the long-wavelength side where stimulated emission additionally influences the bleaching behaviour. The spectral characteristics of the emission cross sections have been shown to be a good measure for the correct radiative lifetime τ 0. This confirmed our recently published value of τ 0=4.9 ns.

EXCITED STATE BEHAVIOR OF PHYTOCHROME Pr

AbstractThe primary excited state processes of phytochrome, the plant chromoprotein responsible for most photomorphogenetic responses, are investigated by picosecond intensity‐dependent transmission measurements. At sufficient high excitation intensity (starting at photon flux densities of about 1′1025 cm−2 s−l) a moderate bleaching of the absorption is observed. For the quantitative analysis of the experimental data a rate equation system approach for the energy levels responsible for the ultrafast transformation Pr→ lumi‐R and the photon transport through the sample was utilized. The following was found for the excited state parameters of the phytochrome Pr: (1) an excited state absorption of the same order of magnitude as the ground state absorption (cross section: S̀exc= 4′10−16 cm−2 at 650 nm), (2) a fast relaxation of the higher excited singlet state on the femtosecond time scale.

The kinetics of type 1 phytochrome in green, light-grown wheat (Triticum aestivum L.)

The kinetics of type 1 phytochrome were investigated in green, light-grown wheat. Phytochrome was measured by a quantitative sandwich enzyme-linked immunosorbent assay using monoclonal antibodies. The assay was capable of detecting down to 150 pg of phytochrome. In red light, rapid first-order destruction of the far-red-light-absorbing form of phytochrome (Pfr) with a half-life of 15 min was observed. Following white light terminated by red, phytochrome synthesis was delayed in darkness by about 15 h compared to plants given a terminal far-red treatment. Synthesis of the red-light-absorbing form of phytochrome (Pr) was zero-order in these experiments. Phytochrome synthesis in far-red light was approximately equal to synthesis in darkness in wheat although net destruction occurred in light-grown Avena sativa tissues in continuous far-red light, as has been reported for other monocotyledons. In wheat, destruction of Pfr apparently did not occur below a certain threshold level of Pfr or Pfr/total phytochrome. These results are consistent with an involvement of type 1 phytochrome in the photoperiodic control of flowering in wheat and other long-day plants.

A PHYTOCHROME PHOTOTRANSFORMATION STUDY USING TWO‐LASER/TWO‐COLOR FLASH PHOTOLYSIS: ANALYSIS OF THE DECAY MECHANISM OF I700*

AbstractThe mechanism of I700 decay, representing an early event in the phytochrome Pr→ Pfr phototransformation, was reanalyzed in the microsecond range by conventional laser flash photolysis as well as by two‐laser/two‐color flash photolysis. Three kinetic models that might describe the I700 decay mechanism following Pr excitation were considered: a parallel, a sequential, and an equilibrium model. These models were used to mathematically simulate both the one‐ and two‐laser flash experiments in an effort to select the model best describing the I700 decay. The sequential model could be excluded already on the basis of the one‐laser flash photolysis results alone. Discussion of the two‐laser/two‐color flash rcsults in the context of the equilibrium and the parallel models is presented.

G-protein from Medicago sativa: functional association to photoreceptors.

G-protein subunits were characterized from Medicago sativa (alfalfa) seedlings. Crude membranes and GTP-Sepharose-purified fractions were electrophoresed on SDS/polyacrylamide gels and analysed by Western blotting with 9193 (anti-alpha common) and AS/7 (anti-alpha t, anti-alpha i1 and anti-alpha i2) polyclonal antibodies. These procedures led to the identification of a specific polypeptide band of about 43 kDa. Another polypeptide reacting with the SW/1 (anti-beta) antibody, of about 37 kDa, was also detected. The 43 kDa polypeptide bound specifically [alpha-32P]GTP by a photoaffinity reaction and was ADP-ribosylated by activated cholera toxin, but not by pertussis toxin. Irradiation of etiolated Medicago sativa protoplast preparations at 660 nm for 1 min produced a maximal increase in the guanosine 5'-[gamma-thio]triphosphate (GTP[35S])-binding rate. After this period of irradiation, the binding rate tended to decrease. The effect of a red-light (660 nm) pulse on the binding rate was reversed when it was immediately followed by a period of far-red (> 730 nm) illumination. These results may suggest that activation of GTP[S]-binding rate was a consequence of conversion of phytochrome Pr into the Ptr form.

Polyclonal antibodies raised to phycocyanins contain components specific for the red-absorbing form of phytochrome

Polyclonal antibodies raised in rabbits to a mixture of sodium-dodecyl-sulphate-denatured C- and allo-phycocyanin, isolated from Anabaena cylindrica, cross-react with 124-kilodalton (kDa) phytochrome from etiolated oats, in enzyme-linked immunosorbent assays and on Western blots. The component(s) of the anti-phycocyanin serum that cross-reacts with phytochrome appears to be specific for the red-absorbing form of phytochrome (Pr). These antibodies can be detached from Pr by irradiation with red light, and thus show photoreversible binding. This property has been used to immunopurify the anti-phytochrome component from the antiserum using red light as the eluting agent. Competition assays and epitope-mapping studies indicate that the anti-phytochrome component may bind to a site located between 6 and 10 kDa from the amino-terminus of etiolated oat phytochrome.

Phototransformation of oat phytochrome with millisecond and submillisecond flashes: The level of the photostationary Pfr/Ptot ratio is modified by photoreversible intermediates

Photoconversion of the red‐absorbing form of phytochrome (Pr) to the far‐red‐absorbing form of phytochrome (Pfr) and vice versa has been measured spectrophotometrically at 10°C in immobilized and soluble phytochrome (118 kdalton), prepared from 5‐day‐old etiolated oat seedlings (Avena saliva L. cv. Sol II). The photostationary equilibrium φ= PfrPtot (with Ptot= total amount of phytochrome Pr+ Pfr) for red light depends on whether it is established by repetitive pulses (≥ 5 s) or by repetitive flashes (≥ 4 ms). In the wavelength region around 660 nm, a lower φ is reached with flashes as compared to that with pulses. This difference becomes negligible if the wavelength is shortened to the 600 nm region, and it also disappears if the fluence of each individual flash is reduced. In contrast, in long‐wavelength red light and short‐wavelength far‐red light, a higher φ is reached with flashes than with pulses.We relate the differences in φ for flash and pulse irradiation to photochromic systems between Pr and photoreversible intermediates in the phototransformation pathway Pr→ Pfr. Thus, light absorption by phytochrome intermediates can be limiting for the quantitative relationship between light signal and Pfr formed.

Theoretical studies of biliprotein chromophores and related Bile pigments by molecular orbital and ramachandran type calculations.

Abstract Ramachandran calculations have been used to gain insight into steric hindrance in bile pigments related to biliprotein chromophores. The high optical activity of denatured phycocyanin, as compared to phycoerythrin, has been related to the asymmetric substitution at ring A, which shifts the equilibrium towards the P‐helical form of the chromophore. Geometric effects on the electronic structures and transitions have then been studied by molecular orbital calculations for several conjugation systems including the chromophores of phycocyanin, phytochrome Pr, cations, cation radicals and tautomeric forms. For these different chromophores some general trends can be deduced. For instance, for a given change in the gross shape (e.g. either unfolding of the molecule from a cyclic‐helical to a fully extended geometry, or upon out‐of‐plane twists of the pyrrole ring A) of the molecules under study, the predicted absorption spectra all change in a similar way. Nonetheless, there are characteristic distinctions between the different n‐systems, both in the transition energies and the charge distribution, which can be related to their known differences in spectroscopic properties and their reactivity.

Spectral properties of soluble and pelletable phytochrome from epicotyls of etiolated pea seedlings

The red-light(R)-absorbing form of phytochrome (Pr) was detected spectrophotometrically in a 20,000 g particulate fraction prepared from a 1,000 g supernatant fraction from epicotyl tissue of pea (Pisum sativum L.) seedlings grown in the dark and only briefly exposed to dim green light. The difference spectrum of phytochrome in this fraction was essentially the same as that of soluble phytochrome from the same tissue. When the non-irradiated 20,000 g particulate fraction was incubated in the dark at 25° C, an absorbance change (decrease) of Pr after actinic red irradiation was found only in the far-red (FR) region. When the 20,000 g particulate fraction was irradiated with R and then incubated in the dark, the FR-absorbing form of phytochrome (Pfr) disappeared spectrally at a rate about half that in the soluble fraction, and the difference spectrum of the Pr which became detectable after dark incubation of the 20,000 g particulate fraction was markedly distorted. In contrast, Pfr in a 20,000 g particulate fraction prepared from tissues irradiated with R did not change optically during dark incubation at 25° C for 60 min, while Pfr in the soluble fraction from the same tissue disappeared in the dark. No dissociation of either Pr or Pfr from the 20,000 g particulate fraction was indicated during a 60-min dark incubation at 25° C, but Pfr in a 20,000 g particulate fraction prepared in vitro from R-irradiated 1,000 g supernatant fraction in the presence of CaCl2 disappeared spectrally and the difference spectrum of Pr in the 20,000 g particulate fraction became quite distorted during the dark incubation.

Possible interpretation of long-wavelength spectral shifts in phytochrome Pr and Pfr forms

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPossible interpretation of long-wavelength spectral shifts in phytochrome Pr and Pfr formsR. Pasternak and G. WagniereCite this: J. Am. Chem. Soc. 1979, 101, 7, 1662–1667Publication Date (Print):March 1, 1979Publication History Published online1 May 2002Published inissue 1 March 1979https://doi.org/10.1021/ja00501a003RIGHTS & PERMISSIONSArticle Views61Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (596 KB) Get e-Alerts Get e-Alerts

Spectral characteristics of phytochrome in vivo and in vitro

The absorption maximum of the far-red absorbing form of phytochrome in the difference spectrum for phototransformation (Pfr λmax) was investigated in vivo and in in vitro pellets from dark grown Hordeum vulgare L. primary leaves. Exposure of pellets in Honda medium from tissue pre-irradiated with red light to far red light gave a Pfr λmax of 734 nm, a slightly longer wavelength than was seen in vivo (730 nm). After incubation as the red absorbing form of phytochrome (Pr) for 2 h at 0° C irradiation with red light showed that Pfr λmax had shifted to shorter wavelength (716 nm) in Honda medium. Further incubation as Pfr for 2 h at 0° C and irradiation with far red light showed that Pfr λmax had shifted to longer wavelength (726 nm). Similar shifts were also seen in other media, although the peak positions were different. Phytochrome remained pelletable throughout these experiments and Pfr λmax is compared to that of soluble phytochrome in similar media. The results are interpreted as indicating changes in molecular environment of the putative phytochrome membrane receptor site and that Pfr λmax can be used to probe the nature of this binding.

Studies on plant bile pigments, II[1]. Chemical and photochemical oxygenation of a phytochrome Pr chromophore model pigment to purpurins.

The chemical and photochemical oxygenation of 2,3-dihydrooctaethyl-1,19(21,24H)-bilindione (1), as a model for the chromophores of both phytochrome Pr and phycocyanin, has been studied in neutral and alkaline solution, and in the presence of zinc ions. By comparison with octaethyl-1,19(21,24H)-bilindione (5), the influence of ring A hydrogenation on the reactivity of bilins has been assessed. In the dark, 1 is attacked selectively and rapidly at C-5 yielding "purpurins", while 5 reacts slowly, and is attacked predominantly at C-10. Photooxidation of 5 yields the tripyrrinic "purpurin" 7 only. Photoreactivity of 1 is considerably enhanced, yielding "purpurins" and "violins" rapidly. In spite of UV-vis and mass spectroscopic similarities, the "purpurin" 7 differs from the "purpurins" 6a,b by the loss of ring A. The facile cleavage at the C-5 methine bridge and the spectroscopic properties of "purpurins" are discussed.