Water Soluble Pigments Containing Xylose and Glucose in Gametangia of the Green Alga, Bryopsis maxima

Several water-soluble pigments were purified from gametangiaof Bryopsis maxima by liquid chromatography and characterizedby pyridylamination and high-performance anion-exchange chromatography.The structure of the main red pigment is proposed based on thedata of infrared spectrum, Mass spectrum, ¹H and ¹³C NMR spectraand pyridylamino analysis. As a consequence, this pigment containeda tetrapyrrole with phytol and a sugar chain comprised of xyloseand glucose. The sequence of the sugars in the chain was determinedbased on its Mass spectrum. The pigment was similar to chlorophyll-originpigments observed in other plants. No aldehyde group, however,was present at C5 in the open tetrapyrrole chain. (Received August 3, 1994; Accepted November 10, 1994)     

Pigment Composition of a Novel Oxygenic Photosynthetic Prokaryote Containing Chlorophyll d as the Major Chlorophyll

The principal pigment found in the majority of oxygenic photosyntheticorganisms is known to be chlorophyll a. However, we isolateda new oxygenic photosynthetic prokaryote that contained chlorophylld as a predominant pigment with chlorophyll a being a minorpigment. Chlorophyll d had previously been noted but its naturaloccurrence and function remained unclear. Cells of the new prokaryotehad an absorption maximum at red region of 714–718 nmdue to chlorophyll d absorption, but no characteristic absorptionpeak of chlorophyll a around 680 nm was observed. Chlorophylld of the new organism was identified spectrophotometricallyin several solvents and its chemical structure was confirmedby NMR and FABMS analysis. The cell also contained a chlorophyllc-like pigment, zeaxanthin and a-carotene but not chlorophyllb and ß-carotene. The content of chlorophyll d accountedfor more than 2% of the cell dry weight, while the content ofchlorophyll a was less than 0.1%. The chlorophyll a/d ratioremained between 0.03 and 0.09 under different culture conditions.The light absorption characteristics and the high content ofchlorophyll d along with the small content of chlorophyll aindicated the existence of a new light utilization mechanisminvolving chlorophyll d. (Received October 7, 1996; Accepted December 16, 1996)     

Some Photosynthetic Characteristics of Tropical Timber Trees as Affected by the Light Regime During Growth

The stomatal conductance and rate of photosynthesis of tropicaltree seedlings are reported (Terminalia ivorensis, T. superba,Triplochiton scleroxylon and Khaya senegalensis). The seedlingswere grown in various light regimes, defined by the photon fluxdensity and red: far-red ratio. Mesophyll conductance and apparentquantum efficiency were calculated. The maximum rates of photosynthesison an area or weight basis depended on the photon flux densityduring growth, being increased by growth at high photon fluxdensity except in the shade tolerant seedlings of K. senegalensis.The stomatal conductance was also highest in leaves which hadbeen grown at high photon flux density. Using plants which hadbeen grown at low photon flux density and contrasting red: far-redratio, it was found that the highest rates of photosynthesiswere attained when the red: far-red ratio was low. The resultsare discussed in relation to what is known of the natural lightclimate, and evaluated in relation to the carbon balance ofseedlings. Terminalia ivorensis, Terminalia superba, Triplochiton scleroxylon, Khaya senegalensis, tropical tree, photosynthesis, stomata, shade, red: far-red     

Pigment Bodies in Fruits of Crimson and High Pigment Lines of Tomatoes

Pigment bodies in fruits of crimson (og^c), high pigment (hp),and crimson-high pigment (og^c hp) lines of tomatoes were observedby electron and light microscopy and compared with those ofnormal red lines and a yellow cultivar. During chloroplast-chromoplasttransformation, two main structurally distinct bodies are produced,their total and relative amounts apparently accounting for theentire range of colours (from very deep red to yellow) characterizingthe mature fruits of these different colour lines. The longnarrow crystalloids, believed to be lycopene, form in associationwith an extended thylakoid system; in senescing (over-ripe)fruit many of these are reduced to shorter irregular forms.The rounded globules are believed to be beta-carotene dissolvedin lipid material derived from membrane lysis. Analytical resultscorroborate microscopic observations that the effect of theog^c gene, as compared with the r⁺ gene for normal red colour,is to increase the lycopene content and lower the beta-carotenecontent. The effect of the hp gene is to increase the levelsof both pigments. The results support the view that the genescontrol the development of fruit pigments which affect chromoplastultrastructure. Lycopersicon esculentum Mill, tomato, fruit, pigment bodies, beta-carotene, lycopene     

The Role of Phytochrome in Anthocyanin Synthesis in Seedlings of Vigna radiata (L.) Wilczek

Previously, it has been demonstrated that the red light-inducedanthocyanin accumulation in mung bean seedlings is mediatedby phytochrome [Dumortier and Vendrig Z. Pflanzenphysiol. 87:313 (1978)]. In this paper the importance of phytochrome forthe accumulation of anthocyanins in seedlings of mung beanswas studied in non-irradiated seedlings and in seedlings irradiatedwith 5 min R. A short FR-irradiation given early after sowing reduced theamount of anthocyanins which were normally found in non-irradiatedseedlings. This indicates that P_FR may be important for at leastpart of the anthocyanin synthesis in the dark. As for the redlight-mediated anthocyanin accumulation, irradiation appearedto be most effective when given to seedlings at the age of 36–48hr. Although the seedlings were sensitive to red light irradiationbefore that time, they were not able to synthesize anthocyaninsuntil they had reached the age of 36 hr. Complete escape ofred/far-red reversibility occurred only when far-red was given12 hr after red, although partial escape could be observed witha shorter time-interval. Furthermore, the time-course of anthocyaninaccumulation after a two-fold R-irradiation was compared withthe effect of a single R-exposure. From the results could beconcluded that the pattern of anthocyanin accumulation is dependenton the time during which P_FR is present in the seedlings. Theseexperiments also indicate that P_FR not only plays a role inthe synthesis of anthocyanins but probably also in their degradation. The results of our study show that phytochrome is importantfor anthocyanin accumulation in non-irradiated mung bean seedlingsas well as in R-irradiated, and that it probably is also involvedin the degradation of the pigment. (Received January 18, 1982; Accepted April 30, 1982)     

Effect of Age and Rehydration on Greening of Wheat Leaves

Photosynthetic pigment synthesis was enhanced upto 15 day withincreasing age of etiolated wheat (Triticum aestivum L. cv.Sonalika) seedlings. The adverse effect of water stress on chlorophyll(Chl) synthesis was observed even after complete rehydrationof the seedlings. Younger seedlings were more prone to stressthan the older ones. The older rehydrated seedlings showed stressrecovery ability in the post lag phase of greening. (Received August 15, 1985; Accepted October 21, 1986)     

The participation of phytochrome in the signal transduction pathway of salt stress responses in Mesembryanthemum crystallinum L.

Continuous irradiation of Mesembryanthemum crystallinum plantswith light of equal amounts of photosynthetically active radiation,but widely different red:far red ratios was used to intervenein phytochrome-mediated signal transduction pathways in thepresence and absence of salt stress. Light with a low ratioof red:far red (in contrast to light with a high ratio of red:farred), caused induction of PEP carboxylase activity, accumulationof the CAM isoform of PEP carboxylase, and the accumulationof malate anion. Taking these as indicators of CAM inductionit is concluded that phytochrome can participate in the signaltransduction pathway leading to CAM in M. crystallinum. A lowratio of red: far red light acted synergystically with saltstress in the induction of these CAM indicators. The simplestinterpretation of this interaction is that the phytochrome-mediatedeffects and salt stress effects acted on the same signal transductionpathway. The accumulation of pinitol was also increased by light witha low ratio of red:far red, consistent with the existence ofa stress syndrome in M. crystallinum which utilizes a commontransduction pathway. A low ratio of red:far red light induced a strong shade avoidanceresponse and, compared to light with a high red:far red ratio,modified chlorophyll content and betacyanin pigment complement. Plants grown in light with a low ratio of red:far red floweredearlier than plants grown in light with a high red:far red ratio. It is concluded that phytochrome can participate in the signaltransduction pathway leading to the induction of both CAM andthe processes which result in pinitol accumulation and pigmentationin M. crystallinum, as well as in the mediation of shade avoidanceand flowering responses. Key words: Mesembryanthemum crystallinum, CAM, phytochrome, signal transduction, drought stress     

Establishment of photoperiodic sensitivity by benzyladenine and a brief red irradiation in dark grown seedlings of Pharbitis nil Chois.

Flowering of etiolated seedlings of Pharbitis nil resulted followinga single, brief red irradiation prior to an inductive dark period.Following this irradiation benzyladenine sprayed on the seedlingsenhanced flowering dramatically and this effect was maximalfor concentrations between 44 and 120µM. In the presenceof benzyladenine a brief (4 to 10 sec) low energy red irradiation(2.6 Wm^–2) resulted in flowering and repeated far-redphotoreversal of this red promotion provided clear evidenceof the sole involvement of phytochrome. However, after suchbrief irradiations the critical dark period for flowering waslonger than is normally found in seedlings grown in light whichindicated that additional photoresponses might be importantin natural conditions. An examination of seedling photosynthesisand assimilate transport indicated that the benzyladenine effecton flowering may relate to its promotion of assimilate and floralstimulus transport to the shoot apex. ¹ Present address: Faculty of Agriculture, Mie University, TsuCity, Mie Prefecture, Japan. (Received August 21, 1978; )     

Accumulation of Pigments during the Greening of Etiolated Seedlings of Hordeum vulgare L.

The pigment changes that occur during transformation of etioplaststo fully developed chloroplasts have been studied in seedlingsof barley (Hordeum vulgare L.) by greening with white lightof low (15–25 µmol m^–2 s^–1) and medium(150 µmol m^–2 s^–1) intensity. At least 24h longer was required in the low light regime for the same concentrationof pigment to be accumulated in the seedlings. The increasein pigment content was mainly due to the synthesis of chlorophyllsa and b. Of the carotenoids present, the increases in the levelsof neoxanthin and, especially, ß-carotene were muchgreater than those observed for the other carotenoids. Levelsof lutein also increased but this change was small by comparisonto those observed for neoxanthin and ß-carotene. Inthe long-term the concentration of violaxanthin remained unalteredalthough significant transient changes were recorded. The levelsof antheraxanthin and zeaxanthin were markedly reduced duringgreening. The rate of pigment synthesis decreased with increasingcell age, i.e. from the base to the tip of the primary leaf.Overall, carotenoid levels increased by approximately 100% atthe base of the seedling but hardly at all at the tip. Key words: Hordeum vulgare, carotenoids, violaxanthin-cycle, etiolation     

Photoregulation of Phenylalanine Ammonia Lyase is not Correlated with Anthocyanin Induction in Photomorphogenetic Mutants of Tomato(Lycopersicon esculentum)

Photoregulation of phenylalanine ammonia lyase (PAL)(EC 4.3.1.5 [EC] )was analyzed in wild type (WT) and mutants: phytochrome dencient-awrea(au), high pigment exhibiting exaggerated phytochrome response(hp) and the double mutant (au.hp) of tomato (Lycopersicon esculentum(Mill.) cv. Ailsa Craig). Red light, acting via phytochrome,stimulates PAL activity in cotyledons and hypocotyls of tomatoseedlings. The time course of photoinduction of PAL in cotyledonsof the mutants (au and au.hp) and WT seedlings has a peak ofactivity at 4 h, after which the activity falls sharply, exceptin hp seedlings where activity is maintained at a high level.In hypocotyls, photoinduction of PAL also shows an initial rise,reaching a maximum at 3 h, followed by a sharp decline in themutants (au and au.hp) and WT seedlings. However in hp seedlingsphotoinduction of PAL is about 3 fold that in WT. The photoinductionof PAL appears to be dependent on de novo synthesis of proteinand nucleic acids. The use of a PAL specific inhibitor a-aminooxyß-phenylpropionic acid indicated that PAL is an essentialcomponent of the anthocyanin biosyn-thetic pathway in the tomatoseedlings. However, a comparison of anthocyanin biosynthesis[Adamse et al. (1989) Photochem. Photobiol. 50: 107] and PALphotoinduction data revealed that phytochrome mediated inductionof PAL and anthocyanin in the tomato seedlings are not correlated.While au and au.hp mutant seedlings show a similar increasein PAL level as in the WT, there is little formation of anthocyaninin these mutant seedlings. The results indicate that, in contrastto the photoregulation of anthocyanin synthesis which is dependenton the presence of the labile phytochrome (IP) pool in tomatoseedlings, the photoinduction of PAL is mediated via a smallpool of phytochrome in au mutant: stable phytochrome (sP) ora residual /P pool. (Received August 6, 1991; Accepted September 27, 1991)     

Time Dependence of Phytochrome-mediated Carotenoid and Chlorophyll Synthesis in Sorghum bicolor L

In 5-day-old etiolated Sorghum seedlings, red light irradiationfor 1 s enhanced carotenoid and chlorophyll accumulation, and5 min of red light treatment saturated the photoresponse. Thedegree of red/far-red photoreversibility of carotenoid accumulationwas dependent on the age of the plant. No significant escapefrom far-red reversibility was observed up to 30 min after theonset of a saturating red light pulse in 5-day-old etiolatedseedlings. Thereafter, the escape was relatively fast and completedwithin 180 min. Sorghum bicolor L, carotenogenesis, phytochrome, time dependence, chlorophyll synthesis     

Action spectrum and characteristics of the light activated disappearance of phytochrome in oat seedlings

The action spectrum for the light-activated destruction of phytochrome in etiolated Avena seedlings has been determined. There are 2 broad maxima, one between 380 and 440 mμ, the other between 600 and 700 mμ. peaking at about 660 mμ. On an incident energy basis, the red region of the spectrum is more efficient than the blue by about one order of magnitude in activating phytochrome disappearance. Both the red absorbing as well as the far-red absorbing forms of phytochrome are destroyed after exposure of Avena seedling to either red or blue light.

From the action spectrum and photoreversibility of pigment loss, we conclude that phytochrome acts as a photoreceptor for the photoactivation of its metabolically-based destruction. We suggest that another pigment might also be associated with the disappearance of phytochrome in oat seedlings exposed to blue light.

     

Gene profiling of the red light signalling pathways in roots

Red light, acting through the phytochromes, controls numerousaspects of plant development. Many of the signal transductionelements downstream of the phytochromes have been identifiedin the aerial portions of the plant; however, very few elementsin red-light signalling have been identified specifically forroots. Gene profiling studies using microarrays and quantitativeReal-Time PCR were performed to characterize gene expressionchanges in roots of Arabidopsis seedlings exposed to 1 h ofred light. Several factors acting downstream of phytochromesin red-light signalling in roots were identified. Some of thegenes found to be differentially expressed in this study havealready been characterized in the red-light-signalling pathwayfor whole plants. For example, PHYTOCHROME KINASE 1 (PKS1),LONG HYPOCOTYL 5 (HY5), EARLY FLOWERING 4 (ELF4), and GIGANTEA(GI) were all significantly up-regulated in roots of seedlingsexposed to 1 h of red light. The up-regulation of SUPPRESSOROF PHYTOCHROME A RESPONSES 1 (SPA1) and CONSTITUTIVE PHOTOMORPHOGENIC1-like (COP1-like) genes suggests that the PHYA-mediated pathwaywas attenuated by red light. In addition, genes involved inlateral root and root hair formation, root plastid development,phenylpropanoid metabolism, and hormone signalling were alsoregulated by exposure to red light. Interestingly, members ofthe RPT2/NPH3 (ROOT PHOTOTROPIC 2/NON PHOTOTROPIC HYPOCOTYL3) family, which have been shown to mediate blue-light-inducedphototropism, were also differentially regulated in roots inred light. Therefore, these results suggest that red and bluelight pathways interact in roots of seedlings and that manyelements involved in red-light-signalling found in the aerialportions of the plant are differentially expressed in rootswithin 1 h of red light exposure. Key words: Arabidopsis, gene profiling, microarray, photomorphogenesis, red light, roots     

Effect of Hypocotyl Excision on Red Light-Mediated Betacyanin Formation in Amaranthus Seedlings

The effect of hypocotyl excision on red light-mediated betacyanininduction in cotyledons of Amaranthus caudatus L. was studiedusing etiolated, 3-day-old half-seedlings and isolated cotyledons.The removal of the hypocotyl promoted betacyanin formation undersafelight conditions in a manner competitive with brief (5 mins),but additive with prolonged (6 h) red illumination. If a papersupport was provided in order to improve the aeration, betacyaninformation in safelight conditions was further stimulated, reducingthe inductive effect of brief, but not changing the action ofprolonged red illumination. These results demonstrate that betacyaninphotoregulation is restricted to cotyledons of A. caudatus seedlings,with no evidence for transmission of light signals between differentorgans. Excision and aeration appear to promote selectivelya very low fluence response (VLFR) induced by safelight, suggestingdifferent mechanisms of phytochrome phototransduction underVLFR, low fluence response induced by brief saturating red light(LFR) and high irradiance reaction (HIR) occurring under prolongedred illumination. Amaranthus caudatus L, betacyanin photoregulation, red light, very low fluence phytochrome reaction     

Intravacuolar Spherical Bodies in Polygonum cuspidatum

The vacuoles in the epidermal cells of light-grown seedlingsof Polygonum cuspidatum were found to contain intensely pigmentedspherical bodies (anthocyanoplasts). Dark-grown seedlings containedsimilar spherical bodies that were unpigmented. The unpigmentedspherical bodies accumulated anthocyanin and turned into anthocyanoplastswhen dark-grown seedlings were irradiated. The unpigmented sphericalbodies of dark-grown seedlings were heavily stained upon treatmentof seedlings with neutral red. The absorption spectra of sphericalbodies and vacuoles showed that the contents of the sphericalbody were different from those of the vacuole. The sphericalbody was stable in darkness or at low temperature but was unstableat 25°C in the light. There was no correlation between theamount of anthocyanin and the percentage of cells that containedspherical bodies, suggesting that, in P. cuspidatum, the sphericalbody is not the main site of anthocyanin synthesis. ²Present address: Department of Applied Biology, Faculty ofTextile Science and Technology, Shinshu University, Ueda, 386Japan     

The Role of the Red/Far-Red Ratio in the Response of Tropical Tree Seedlings to Shade

The West African species Khaya senegalensis and Terminalia ivorensiswere grown in a controlled environment, varying the photon fluxdensity in the range 18–610 µmol m^–2 s^–1and the red/far-red ratio over an appropriate range to simulatethe shade of a tree canopy versus unattenuated daylight. Theshade tolerant seedlings of Khaya were relatively insensitiveto the red/far-red ratio. The light demanding Terminalia wasconsiderably affected: when the ratio was low the specific leafarea was increased and the leaves produced were very much largerin area. Thus, the Leaf Area Ratio was enhanced and the plantsdisplayed an increase in Relative Growth Rate. Khaya, Terminalia, tropical trees, shade, red/far-red ratio     

Phytochrome-regulated PIL1 derepression is developmentally modulated

We define the photoresponsiveness, during seedling de-etiolation,of PHYTOCHROME-INTERACTING FACTOR 3-LIKE 1 (PIL1), initiallyidentified by microarray analysis as an early-response genethat is robustly repressed by first exposure to light. We showthat PIL1 mRNA abundance declines rapidly, with a half-timeof 15 min, to a new steady-state level, 10-fold below the initialdark level, within 45 min of first exposure to red light. Analysisof phy-null mutants indicates that multiple phytochromes, includingphyA and phyB, impose this repression. Conversely, PIL1 expressionis rapidly derepressed by subsequent far-red irradiation ofpreviously red light-exposed seedlings. However, the magnitudeof this derepression is modulated over time, in a biphasic manner,in response to increasing duration of pre-exposure to continuousred light: (i) an early phase (up to about 6 h) of relativelyrapidly increasing effectiveness of far-red reversal of repression,as declining phyA levels relieve initial very low fluence suppressionof this response; and (ii) a second phase (beyond 6 h) of graduallydeclining effectiveness of far-red reversal, to only 20% ofmaximal derepression, within 36 h of continuous red light exposure,with no evidence of circadian modulation of this responsiveness,an observation in striking contrast to a previous report forentrained, green seedlings exposed to vegetative shade. Thesedata, together with analysis of phytochrome signaling mutantsand overexpressors with aberrant de-etiolation phenotypes, suggestthat the second-phase decline in robustness of PIL1 derepressionis an indirect consequence of the global developmental transitionfrom the etiolated to the de-etiolated state, and that circadiancoupling of derepression requires entrainment.     

On the Relationship between Photocontrol of Phycoerythrin Formation and Photoreversible Pigment of Scheibe

Dose-response of photocontrolled phycobiliprotein formationwas studied with two types of Tolypothrix tenuis cells havingdifferent content of photoreversible pigment (PRP) of Scheibe[cf. Scheibe (1972) Science 176: 1037]. PRP was not detectablein cells grown in a medium rich in nitrogen source under weakred light (normal cells) while the content was much larger (morethan 10 times) in cells incubated in light under nitrogen-deficientconditions [nitrogen-deficient cells, cf. Ohki and Fujita (1979)Plant & Cell Physiol. 20: 1341]. Both cells were found toform phycoerythrin (PE) in the dark after a short green illumination,while red illumination suppressed its formation. The amount of PE formation depended on the dose of green orred preillumination. Despite a large difference in content ofPRP of Scheibe, the dose-response of PE formation induced bygreen light was almost the same in both types of cells. Suppressionby red light in normal cells required a dose larger than thatin nitrogen-deficient cells. The results indicate that PRP ofScheibe formed during the incubation under nitrogen-deficientconditions does not act as the photoreceptor in photocontrolof PE formation. (Received September 29, 1980; Accepted January 6, 1981)     

Virulence of Agrobacterium on Larix decidua and Their Cellular Interactions as Depicted by Scanning Electron Microscopy

European larch (Larix decidua Mill.) seedlings were inoculatedwith a number of Agrobacterium strains to screen susceptibilityto infection by agrobacteria. Nine of fourteen Agrobacteriumstrains tested were virulent on this conifer species. The attachmentof virulent Agrobacterium to larch seedling tissues was examinedusing scanning electron microscopy. Electron micrographs showedthe attachment specificity of virulent Agrobacterium to larchcells at wound sites in a manner similar to that described forcells of susceptible dicotyledonous angiosperms, indicatinga host-parasite relationship between oncogenic Agrobacteriumspp. and young seedlings of European larch. These unique electronmicrographs provide the first opportunity to document the compatibleinteractions of Agrobacterium and a conifer at the cellularlevel. Further, the evaluation of tumour formation frequencysuggested that the interactions between Agrobacterium and Europeanlarch were affected by wound site, position of inoculation,age of plant tissues, and time of co-culture. Successful infectionof Agrobacterium resulted in genetic transformation of hostcells. Agrobacterium-mediated DNA transfer and expression of bacterialgenes in larch tissues were confirmed by both Southern blotanalysis and opine assay with the transformed tissues. Key words: Agrobacterium, Larix decidua, cellular interaction, transformation, DNA transfer, scanning electron microscopy     

PHOTOCONTROL AND TEMPERATURE DEPENDENCE OF GERMINATION OF RUMEX SEEDS

1. Light is not obligatory for the germination of the seed ofRumex obtusifolius L. subsp.agrestis DANSER, which has beenregarded as being a typical light sensitive seed. Even in continuousdarkness, a short period of high (30°) or low temperature(5°) treatment evokes germination very readily. 2. Germination is markedly promoted by 1 min exposure to a redlight and this red light effect is completely removed by 1-hrexposure to a far-red light. Alternations of the red and far-redradiation bring about an alternate promotion and inhihibitionof germination. 3. When a dark interval is inserted between the red and thefar-red treatments, inhibition of germination becomes less distinctas the duration of darkness increases. When the seeds are irradiatedwith far-red prior to red, with an inserted darkness, germinationpromotion due to the red light also decreases with the durationof inserted darkness. 4. Complicated interdependence between the light and temperatureeffects are demonstrated. This suggests a participation of somereactants besides pigments in the photoreaction. 5. The observed interdependence between the light and temperatureeffects on the germination of Rumex seeds implies that, if,as BORTHWICK has assumed, two forms of pigment, viz., a far-red-absorbingform and a red-absorbing one, are participating in the photoreaction,they should be presumed to coexist from the start of imbibition. (Received September 27, 1960; )