bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Growth Regulators and Herbicides on Photosynthetic Partial Reactions in Isolated Leaf Cells
Authors: KULANDAIVELU G. , GNANAM A.
Published: April 2006

The effect of indoleacetic acid, gibberellic acid, 2,4‐dichloro‐phenoxyacetic acid and amitrole at various concentration levels ranging from 0.05 to 1.0 mM on the photosynthetic evolution of O2 and 14CO2 fixation by isolated leaf cells was studied. The plant growth regulators enhanced O2 evolution and 14CO2 fixation at low concentrations and were inhibitory beyond a critical level. The amitrole had an inhibitory effect at all the concentration levels used. All the substances exhibited similar patterns of effect on the ferricyanide reduction by isolated chloroplasts and on the electron transport rates of sub‐chloro‐plast particles containing PS‐I and PS‐II independently, under non‐phosphorylating conditions. As was seen from the response in all the three electron transport systems of the chloroplast studied, the electron transport chain connecting PS‐II and PS‐I could be considered as a possible site of action at least for the growth regulating substances as it is the only part that is common to all the three reactions. The phosphorylation associated with this part of the electron transport was “inhibited” by the substances even at the lowest concentration used. The stimulation of non‐phosphorylating electron flow, with a simultaneous reduction in the rate of ATP synthesis, at low concentration levels indicated that these substances played a possible uncoupling role. The amitrole on the other hand appeared to have a generalized non‐specific inhibitory action on all the partial reactions of photosynthesis.
Enhancement of Gibberellin Activity by Ethylenediaminetetraacetic Acid in Celery Seeds and Embryoless Barley Seeds
Authors: PALEVITCH D. , THOMAS T. H.
Published: April 2006

The phytochrome‐controlled dormancy of celery seeds (Apium graveolens L.) can be broken by exogenously applied growth regulators. Gibberellins, especially the mixture of GA4 and GA7 appeared to be the primary stimuli for germination of darkincubated seeds. However, concentrations less than 1 mM were ineffective in replacing the light requirement in one celery cultivar (cv.Utah), and in another cultivar (cv.Lathom Blanching), concentrations above 1 mM were insufficient. The addition of ethylenediaminetetraacetic acid (EDTA) to gibberellins, increased markedly their activity and reduced by several orders of magnitude the gibberellin concentrations needed to stimulate a light treatment. This synergistic activity is similar to the effect of benzyladenine (BA) or Succinic acid‐2,2‐dimethylhydrazide (SADH) when added to gibberellins. In a diverse plant system, the mixture of gibberellin with EDTA increased significantly the amount of reducing sugars released by embryoless barley seeds.
Phase Change in Hedera helix: Induction of the Mature to Juvenile Phase Change by Gibberellin A3
Authors: ROGLER CHARLES E. , HACKETT WESLEY P.
Published: April 2006

A sensitive and reproducible method to obtain GA3 induced morphological reversion of mature Hedera helix to the juvenile form has been developed. Dose response experiments indicate that GA3 stimulates reversion over a 50–100 fold range with a half maximal response at approximately 0.5 μg GA3 per plant. The individual characteristics involved in phase change revert to the juvenile form in a sequential manner as GA3 dose is increased. Variations in light intensity from 1.2–3.6 × 104 lux and temperature from 15 to 26°C do not affect this hormonal response. Other growth regulators including indoleacetic acid, kinetin, abscisic acid and (2‐chloroethyl)phosphonic acid (Ethephon) are inactive but other gibberellins (GA1 and a mixture of A4–A7) are active in stimulating reversion. Therefore, the response is specific for gibberellins as a class of hormones but non‐specific for a particular form of gibberellin. The significance of this response in relation to juvenility in woody plants is discussed.
Redistribution of Endogenous Indoleacetic Acid, Abscisic Acid and Gibberellins in Geotropically Stimulated Ribes nigrum Shoots
Authors: EL‐ANTABLY HAMED M. M.
Published: April 2006

The presence of IAA, ABA and gibberellins in extracts of shoots of Ribes nigrum was demonstrated by gas‐liquid chroma‐tography (GLC) for both IAA and ABA and by the lettuce hypocotyl assay for gibberellins. Quantitative estimation of the three substances in extracts from upper and lower halves of shoots which had been kept horizontal, and which showed negative geotropic response after 4 h, indicated a redistribution of hormones during the geotropic stimulation. The ratio of the hormones in lower and upper halves was 3.8:1 and 2.8:1 for IAA and giberellins respectively, whereas the ratio of ABA in upper and lower halves was 2.1:1. There is, however, no evidence for the participation of gibberellins and ABA in the early development of negative geotropic curvatures, since shoots of intact Vicia faba seedlings treated with 100 mg/1 solution of GA3, ABA and 10 mg/1 IAA for 30 min prior to geotropic stimulation, developed negative geotropic curvatures, although shoots pretreated with 50 and 100 mg/1 IAA did not develop curvature.
Influence of UV‐B Radiation on Early Seedling Growth and Translocation of 65Zn from Cotyledons in Cotton
Authors: AMBLER J. E. , KRIZEK D. T. , SEMENIUK P.
Published: April 2006

The influence of UV‐B radiation from filtered or unfiltered fluorescent sunlamps on early seedling growth and translocation of 65Zn from cotyledons to the shoot was examined in two cultivars of cotton, Acala and Gregg. Ten‐day‐old seedlings which had been irradiated in the greenhouse for 6 h continuously each day for 14 days with 0.81 or 1.61 W × m‐2 UV‐B radiation under two unfiltered FS‐40 sunlamps, showed pronounced phytotoxic damage. This was characterized at first by bronzing and glazing of the cotyledons and later by upward curling of the leaves and abscission. Leaf expansion, dry matter accumulation, and mobilization of 65Zn from the cotyledons was severely impaired in the young developing shoot under unfiltered UV‐B radiation. A significant stress response also was observed in seedlings exposed to 0.61 W × m‐2 UV‐B radiation through a polystyrene filter and 0.73 W × m‐2 UV‐B radiation through a cellulose‐acetate filter. This stress response was characterized by the formation of a red pigment in the petioles of the cotyledons, reduced leaf expansion, and reduced transport of 65Zn. Control seedlings exposed to 0.03 W × m‐2 UV‐B radiation through a mylar filter were green, had maximum leaf size and dry‐matter accumulation, and had the greatest percentage of 65Zn translocated from the cotyledons.
Influence of Ultraviolet Radiation on Germination and Early Seedling Growth
Authors: KRIZEK DONALD T.
Published: April 2006

The influence of UV‐B radiation (280–320 nm) from filtered and unfiltered FS‐40 fluorescent sunlamps on germination and early seedling growth was examined for a range of vegetables (tomato, radish, cucumber, lettuce, and bean) and field crops (wheat, cotton, soybean, and millet). Continuous exposure of seeds for 3 days to 26.9 × 10−2 W × m−2 UV‐B radiation (280–320 nm) at 25°C, had a slight effect on fresh weight of seedlings but no appreciable influence on germination percentage, or dry weight of seedlings. Extending the time of exposure to 6 days, however, resulted in abnormal seedling growth in all species but wheat. Typical responses were short, stubby roots, bronzing of the cotyledons, increased pigmentation, and abnormal curvature of the shoots.
Abscisic Acid Analysis in Vitis vinifera in the Period of Endogenous Bud Dormancy by High Pressure Liquid Chromatography
Authors: DÜRING H. , BACHMANN O.
Published: April 2006

In buds and nodes of Vitis vinifera L. cv. Riesling, the content of abscisic acid (ABA) was measured by high pressure liquid chromatography and related to bud dormancy. In the period of endogenous bud dormancy (rate of bud break is low or zero under favourable climatic conditions) the ABA content increased twelvefold. This indicates a causal relationship between endogenous bud dormancy and ABA.
Simulation of Hormone Transport in Petiole Segments of Coleus
Authors: VEEN H. , FRISSEL M. J.
Published: April 2006

Translocation and distribution of abscisic‐(1‐14C) acid and of (5‐3H)indol‐3yl‐acetic acid in agar cylinders and in boiled and fresh petiole segments of Coleus scutellarioides Bentham have been studied by liquid scintillation counting. The hormones were simultaneously applied in donor blocks of agar. Transport and distribution data of the two compounds were compared with those of (36Cl‐)chloride in the same systems. From the data on movement in agar cylinders, diffusion coefficients of the transported compounds were approximated using a simulation model in which it was assumed that the movement was controlled by diffusion only. Movement in boiled tissue segments fitted the model if a correction factor was included in the equation for diffusion. Acropetal movement of indol‐3yl‐acetic acid in fresh petiole segments can be entirely explained in terms of passive transport and for basipetal transport it seems to be a major component. Movement of abscisic acid and of chloride in fresh petiole segments fit also a model based on diffusion. The limitations of the simulation model are discussed.
Emergence and Seedling Growth of a Cultivated and a Wild Strain of Safflower under Various Amounts of Simulated Rainfall
Authors: BASSIRI ABDOLLAH , SIONIT NASSER
Published: April 2006

Two separate experiments were conducted to investigate the effects of different planting depths and irrigation regimes on the emergence and seedling heights of a cultivated (Carthamus tinctorius L. cv. Arak 2811) and a wild strain (C. oxyacantha Bieb.) of safflower. In the first experiment, three planting depths (0.5, 2.0 and 3.5 cm) and four water levels (6,9,12, and 15 mm) were used. Water was applied only once at the start of the experiment. For Arak 2811, the highest emergence percentage and seedling height were obtained when seeds were planted 0.5 cm deep in the soil and irrigated with the equivalent of 12 mm of rainfall.

In the second experiment, five water levels (3, 6, 9, 12 and 15 mm) were applied at 3‐day intervals for a period of 25 days and the planting depth was 0.5 cm. For Arak 2811, the seedlings emerged within 4 to 7 days after the first watering while for the wild strain, the emergence started on the 4th day and continued up to the 17th day. The emergence percentage of the wild safflower was almost half of that of the cultivated strain. However, the emerged wild seedlings were much more resistant to low available water than the seedlings of the cultivated variety of safflower.
Freeze Preservation of Cultured Plant Cells
Authors: NAG K. K. , STREET H. E.
Published: April 2006

A basic technique for successful freeze preservation and storage at ‐196°C of cultured plant cells and an assay of percentage survival following the freezing‐storage‐thawing procedure are described. These techniques have been applied to suspension cultures of carrot (3 cell lines), belladonna and sycamore. Dimethyl sulfoxide (DMSO) and glycerol, when appropriately applied, were the most effective cryoprotectants tested. Although these cryoprotectants were of low toxicity and did not cause alterations in the cytology and growth potential of the recovered cells, the cell lines differed in their sensitivity to the toxicity of these cryoprotectants. Small meristematic cells survived the freezing‐thawing procedure better than larger more highly vacuolated cells. Specific differences in survival are in part explained in terms of differences in cell morphology.
Freeze Preservation of Cultured Plant Cells
Authors: NAG K. K. , STREET H. E.
Published: April 2006

A slow rate of cooling (1–2°C/min) is essential for high survival during the freezing phace. Death of cells during this phase takes place at temperatures below the freezing point of the suspending media, predominantly in the temperature range 10°C to −50°C. In the absence of cryoprotectants survival drops to zero between −30°C and −40°C. Fast thawing (water bath at 37°C giving a rate of temperature rise of 120°C/min between −50°C and −10°C) yields the highest recovery of viable cells. An interaction between cooling rate and thawing rate was demonstrated; this served to emphasize the importance of fast thawing. Under the best conditions realized in these experiments the percentage survival of cells cooled to −196°C was for carrot 70–75%, for belladonna 30–40% and for sycamore 20–25%. Storage for long periods (up to 10 months) at −196°C did not lead to any decline in percentage survival. Carrot cultures which had been stored for 10 months at −196°C showed no change in cell morphology or growth potential in culture and retained embryogenic potential.
Effects of AMO‐1618 and B‐995 on Growth and Endogenous Gibberellin Content of Cupressus arizonica seedlings
Authors: KUO C. G. , PHARIS R. P.
Published: April 2006

Soil drenches of 250, 500 or 1000 mg/l of the growth retardants AMO‐1618 or B‐995 effectively reduced dry matter production and stem elongation in young seedlings of Cupressus arizonica Greene. In seedlings treated with AMO‐1618, the acidic, ethyl acetate‐soluble gibberellin‐like substances (GAs), as detected. by bioassay, were reduced to almost undetectable levels. However, the endogenous GA content in seedlings treated with B‐995 were at least 11‐fold greater than in control seedlings and differed as well in chromatographic characteristics, being of a more polar nature than the endogenous GAs of control seedlings. It was concluded that while AMO‐1618 probably acts through interference with GA biosynthesis, B‐995 may act through the interconversion of GAs.
Effects of Activated Charcoal on Growth and Morphogenesis in Cell Cultures
Authors: FRIDBORG GUNNAR , ERIKSSON TAGE
Published: April 2006

The effects of activated charcoal on growth and morphogenesis in plate cultures of different plant cells have been studied. It was shown that medium containing charcoal induced embryogenesis in cultures of Daucus carota in which embryo formation could not be brought about by omitting auxin from the medium. Charcoal‐medium also induced abundant root formation in older cultures of Allium cepa, which normally did not produce roots. The growth of cultures of Glycine max and Haplopappus gracilis was totally inhibited by charcoal. It is thought that activated charcoal removes substances from the medium, one of which might be auxin.
Control of Light‐Induced Carotenoid Synthesis in Raphanus Seedlings by Phytochrome
Authors: LICHTENTHALER HARTMUT K.
Published: April 2006

The effect of short pulses of red and or far‐red light on the formation of individual carotenoids was tested in etiolated radish seedlings (Raphanus sativus L.). Red light induces an enhanced synthesis of β‐carotene, lutein. violaxanthin and neoxanthin, while the level of antheraxanthin is decreased. Far‐red light reverses the red light effects to the level of the far‐red light control. The data indicate that in radish seedlings active phytochrome Pfr initiates the light‐induced carotenoid synthesis, which is bound to thylakoid formation.
Acidification of the Medium Associated with Normal and Fusicoccin‐Induced Seed Germination
Authors: LADO PIERA , RASI‐CALDOGNO FRANCA , COLOMBO ROBERTA
Published: April 2006

Fusicoccin, a toxin stimulating cell enlargement and inducing proton extrusion in various plant tissues, has been shown to replace kinetin, gibberellic acid and red light in breaking seed dormancy. It also removes the inhibitory effect of abscisic acid.

The present data also show that the stimulating effect of fucicoccin on embryo growth of decoated radish (Raphanus sativus L.) and maize (Zea mays) seeds and on the development of maize embryos is accompanied by an early, significant acidification of the medium. Acidification of the medium is also observed when fusicoccin reverses the abscisic acid‐induced inhibition of germination. These results support the hypothesis that the mode of action of fusicoccin in promoting germination involves, as in stimulation of cell enlargement, the activation at the cell membrane level of proton extrusion processes.

The physiological significance of fusicoccin‐induced release of protons at the onset of germination is discussed in comparison with the results concerning the mechanism of action of fusicoccin on cell enlargement in other plant materials.
A System for Continuous Measurement of Photosynthetic Rate and Dark Respiration at Constant CO2‐Level
Authors: NILSEN STEIN , KRISTIANSEN ERNST , HALLDAL PER
Published: April 2006

A system for maintaining a constant CO2‐level during photosynthesis and dark respiration in an assimilation chamber is described. The assimilation chamber has two loops for control of the CO2‐level. If the CO2‐concentration is increased over a preset value, CO2 is removed by passing the gas flow over a lime filter. If CO2 is consumed, concentrated CO2 is added to the system. The system is operated through the computer in the Phytotron and has been constructed mainly for studies of dusk and dawn effects on photosynthesis where a high degree of control of the CO2‐level in the system is of the utmost importance.
Preconditioning of Tobacco and Bean Leaves to Heat Shock by High Temperature or NaCl
Authors: BENZIONI ALIZA , ITAI CHANNAN
Published: April 2006

The present paper examines whether leaves subjected to heat or salt pretreatment are better adapted to heat shock than untreated leaves. Such adaptation could result from either acquired thermo‐stability and/or better recovery. The rates of metabolic processes such as 14CO2 fixation, 14C‐leucine incorporation into the TCA insoluble fraction, 32P incorporation into phospholipids and 36Cl efflux were used as indicators of adaptability. It was found that pretreatments (heat or salt) protect leaves only slightly against the short‐term effects of a heat treatment, but have a pronounced effect on recovery. Cytokinin level was reduced by heat shock, and as in the case of metabolic response, pretreatment had no effect on this reduction.
Lower and Upper Critical Zinc Levels in Relation to Cotton Growth and Development
Authors: OHKI KENNETH
Published: April 2006

Solution culture experiments in the greenhouse were conducted to determine the lower and upper critical Zn levels relative to early cotton (Gossypium hirsutum L.) growth and development. Upland cotton ‘Coker 310’ was grown in nutrient solution with fourteen Zn levels ranging from 0 to 10,000 μg/liter. The plants were grown for 31 days, harvested and analyzed for Zn.

At Zn levels of less than 20 μg/I, top dry weight, root dry weight, plant height, node number and squares produced were reduced as compared to plants supplied with adequate Zn. Toxicities were induced at 2000 μg/I and higher. Root dry weight was not influenced by Zn levels to 10,000 μg/I. The lower critical Zn levels where Zn is required at a minimum concentration for maximum growth were from 8 to 11 μg/I in blades 1 through 5, respectively. The upper critical Zn levels where maximum Zn concentration in blade tissue can be tolerated for maximum growth were from 130 to 300 μg/g for blades 1 to 5, respectively. Blade 3, the recently matured leaf, was selected as the representative tissue for analysis. The lower and upper critical Zn levels in blade 3 were 11 and 200 μg/g, respectively.
Isolation and Partial Characterization of DNA in Capsular Preparations of Rhizobium trifolii
Authors: WULLSTEIN L. H. , BRUENING M. L. , WULLSTEIN B. M. , SHERWOOD M.
Published: April 2006

The capsular polysaccharides from thymidine‐(methyl‐3H) labeled cultures of Rhizobium trifolii; strain 162S7 (Nitragin Co.) were centrifuged from bacterial cells and collected by ethanol precipitation. Following the addition of unlabeled carrier nucleic acids, labeled DNA, termed cap‐DNA, was isolated from the capsular polysaccharides. Cap‐DNA absorbed maximally at H‐260 nm and was DNase sensitive. Approximately 11 μg of 3H‐cap‐DNA were consistently isolated per liter of 48 h cultures. Cap‐DNA production was generally synchronized with the synthesis of the capsular polysaccharide and bacterial growth, attaining maximum recoverable amounts in 48 h cultures. By five days of culture growth, significant decreases in the amount of recoverable cap‐DNA were noted. The presence of label in the cap‐DNA demonstrated that the cap‐DNA originated via de novo synthesis by the Rhizobium cells rather than from an anomalous source. The cap‐DNA and intracellular Rhizobium DNA had similar buoyant densities of p= 1.719, indicating that cap‐DNA arose specifically from the intracellular DNA. In 48‐h cultures the specific activity of the cap‐DNA was about one‐third that of the intracellular DNA. This implies intracellular DNA was released during early growth with a relatively low specific activity which diluted the isotopic label of DNA released later. The evidence suggests lysogeny was the principal release mechanism.
The effect of Aging on Ion Uptake by Excised Barley Roots
Authors: JACOBSON L. , YOUNG L. C. T.
Published: April 2006

When excised barley (Hodeum Vulgare L.) roots were aged, the rate of uptake of K and C1 increased raching a maximum in about 14 to 18 h. At its maximum the uptake rate was approxiamately twice that of the freshly excised root materila. Respiratory activity declined markedly during the aging period. Although excision was an essential requirement for uptake enhancement, washing was not. Both the uptake and aging processes were shown ot be unresponsive to the presence or absence of Ca in the tratment solutions. Because of cation exchange properties, the change in the total cation content of the root material was a more meaningful measure of the metabolically mediated cation uptake than was the change in content of the test cation itself. The pluggin of xylem vessels with protein and pectin‐like substances was observed to increase with aging. It is proposed that the occlusion of the vessels may account for an apparent increaase in uptake since the obstruction could reduce a concurrent loss of ions through the cut ends of the root segments.
Rapid Effects on Ion and Water Uptake Induced by Changes of Water Potential in Young Wheat Plants
Authors: ERLANDSSON GUNVOR
Published: April 2006

The effect of rapid changes in the water potential of the root medium or the atmosphere was investigated with particular respect to water and ion uptake in young wheat plants. Either PEG 400 or PEG 6000 were added to the nutrient solution, so that the water potential was decreased from about 0 to –5 bars and –13 bars, respectively. Both water and ion uptake immediately decreased when the water potential of the medium was reduced. By raising the humidity around the shoots from 1400 N m−2 (60% RH) to about 2300 N m−2 (100% RH) water uptake decreased, whereas ion uptake transiently increased. If sodium chloride was added to reduce the water potential of the mutrient solution, ion uptake was found to decrease to essentially the same level as when PEG was used. It is suggested that a change in the water potential of the plants has effects on the active‐ion‐transport mechanism.
Metabolism of Gibberellin A4 by Vegetative Shoots of Douglas Fir at Three Stages of Ontogeny
Authors: WAMPLE R. L. , DURLEY R. C. , PHARIS R. P.
Published: April 2006

Vegetative shoots of coastal Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings rapidly metabolized 1,2[3H]‐gibberllin A4 (GA4) to GA2, GA34 and 6 unknown acidie, ethyl acetate‐soluble compounds. The kinetics of formation of each compound depended upon the stage of ontogeny, metabolism being most rapid during bud set and bud break and least rapid during elongation. Translocation of radioactivity was greatest at the bud set stage. By hour 72 large amounts (65%) of neutral, ehter‐soluble compunds were formed at the stage of bud break and lesser, but significant amounts (40%) at bud set. Less than 15% of the radioactivity went into neutral ether during the elongation stage. Douglas fir appears to have an efficient system for con‐version of the relatively non‐polar GA34. This, coupled with the formation of neutral, ether‐soluble and acidie, n‐butanol‐soluble substances, may regulate the effective level of biologically active exogenous and/or endogenous GAs in this conifer.
The Recovery of Cytokinins during Extraction and Purification of Clubroot Tissue
Authors: DEKHUIJZEN H. M. , GEVERS Ch. Th.
Published: April 2006

Losses of one naturally occurring cytokinin (zeatin) and one synthetic cytoknin (kinetin) were determined during purification of turnips (Brassica compestris) infected by Plasmodiophora brassicae (clubroot). A known amount of zeatin and 8‐14C‐kinetin was added after homogenization of plant material in ethanol or water. The commonly used practice to purify the aqueous residues of the homogenate by partitioning with petroleum ether was omitted because of emulsion formation. Losses due to emulsion formation and occlusion of 8‐14C‐kinetin into non‐water soluble plant material could be prevented by extractionof clubroot tissue with water instead of ethanol. To minimize enzyme activity the aqueous homogenate was kept at 100°C for 5 min. High molecular weight compounds were removed by dialysis against water and the diffusible fraction was partitioned with n‐butanol at pH 8.2.

It was shown that a rapid evaporation of n‐butanol under reduced pressure at high temperature caused less breakdown of 8‐14C‐kinetin than prologned treatment at a low temperature.

To minimize breakdown to zeatin riboside the butanol fraction was purified further on cation cellulose‐phosphate exchanger instead of on strong acid Dowex H+. 8‐14C‐kinetin was separated from zeatin by column chromatography on Sephadex LH20, and yielded 86% of the amount originally added to a plant homogenate.

The zeatin containing fractions were further purified on thin layer chromatography (TLC) silicagel plates and injected into a high pressure liquid chromatograph. A yield of 60% could be estimated from the amount (15 μg) orignally added to 50 g clubroot tissue.
Effect of Salinity and Potassium on the Uptake of Nitrogen and on Nitrogen Metabolism in Young Barley Plants
Authors: HELAL M. , KOCH K. , MENGEL K.
Published: April 2006

In a solution culture experiment with 4‐week‐old barley plants (variety Villa) the influence of NaCl salinization and of KCl additions on the uptake and turnover of labelled N (15NH415NO3) was studied. Labelled N was applied for 24 h at the end of the growth period.

Salinization impaired growth and uptake of labelled N. The incorporation of labelled N into the protein fraction, however, was improved by NaCl salinization. Additions of KCl to the nutrient solution diminished the negative effect of NaCl salinization on growth. At both NaCl salinization levels (60 and 120 mM) K additions favoured the uptake of labelled N and particularly its incorporation into the protein fraction.

It is suggested that the negative influence of the NaCl stress is not primarily due to an impaired protein synthesis, but is possibly caused by a deterimental effect of Na on other metabolic processes.
Blue Light Induction of Barley Leaf Unfolding. A Phytochrome Reaction?
Authors: DEUTCH BENTE , DEUTCH† BERNHARD I.
Published: April 2006

Low‐energy blue light (450, 475 nm) has been found to induced unfolding of etiolated barley leaves (Hordeum rulgare cv. Ingrid). This induction can be reversed by far‐red light. Barley leaf unfolding is normally stimulated by red light, reversed by far‐red light, and can be considered to be a typical phytochrome controlled response. It is possible to explain the effects by red and blue light as mediated by the same photoreceptor. The phototransformation of this pigment results in two forms, P2 and P4, to which physiological activity can be ascribed. The red and blue light affect different steps in a cyclical photoconversion. Calculated theoretical dose response curves are presented for such a model in agreement with the experimental data.
Recovery of Cytokinins from Cation Exchange Resins
Authors: VREMAN HENDRIK J. , CORSE JOSEPH
Published: April 2006

Cytokinins exhibit great affinity for the polystyrene matrix of Dowex‐50 cation exchange resins. Model experiments showed that only c. 20% of the applied 2‐methylthio‐trans‐zeatin and c. 70% of the trans‐zeatin are eluted from AG 50W columns with six bed volumes of 1 N NH4 OH. Inclusion of 70% (v/v) ethanol in the eluant increases the recovery to c. 55 and 85% respectively. No additional recovery was obtained upon continued elution to 14 bed volumes. Similar experiments with Duolite CS‐101, a weak acid cation exchange resin with acrylic matrix, showed that c. 95% of the applied 2‐methylthio derivatives of isopentenyladenine and zeatin are recovered from the resin with six bed volumes of 70% (v/v) ethanol (pH 10) or 1 N NH4OH in 70% (v/v) ethanol. The less modified cytokinins, isopentenyladenosine and ribosylzeatin, are recovered completely under these conditions. Recovery of cytokinins was determined by means of high‐pressure liquid chromatography of the column eluates.
Veränderungen der Aktivitäten von Glutamatdehydrogenase, Malatdehydrogenase und Isocitratdehydrogenase im Verlauf des Wachstums batchvermehrter Zellsuspensionskulturen von Pisum unter Langtag‐ und Dauerdunkelbedingungen
Authors: PAHLICH E. , MAYWALD H. , HARMS H.
Published: April 2006

Changes of the Specific Activities of Glutamate Dehydrogenase Malate Dehydrogenase and Isocitrate Dehydrogenase in Light‐ and Dark‐Grown Suspension Cultures of Root Cells from Pisum sativum.
The Movement and Physiological Effect of Indoleacetic Acid Following Point Applications to Root Tips of Zea mays
Authors: DAVIES PETER J. , DORO JOSEPH A. , TARBOX ANDREW W.
Published: April 2006

Pinpoint applications of labeled and non‐labeled indoleacetic acid (IAA) on resin beads were made, without injury, to vertical roots of intact seedlings of Zea mays. Points of application were at the extreme tip of the root, 0.5, 2 and 5 mm from the root tip. The movement of label and bending of the roots was recorded. Radiolabel was found to move basipetally from the extreme tip and 0.5 mm applications to a similar extent, reaching 8 mm from the tip. The level of label in the growing zone after 4 h was 10% of that found in the extreme tip. Movement from 2 and 5 mm applications was equal in both directions. Higher amounts of non‐labeled IAA caused bending towards the point of application if applied at 0.5 or 2 mm but not at 5 mm from the tip. It is proposed that any endogenous IAA in the root cap could move to the growing zone and cause a unilateral inhibition of growth, provided that it was in the same transport pool as the exogenously applied IAA.
The Identification of Zeatin Glucoside from Coconut Milk
Authors: VAN STADEN J.
Published: April 2006

By means of chromatographic, mass spectrometric and enzymatic techniques the major cytokinin in butanol extracts from the milk of Cocos nucifera fruits was identified as zeatin glucoside.
Changes in the Amount of Complex Lipids in the Seeds and in the Pericarp during the Development of Ivy Fruit (Hedera helix)
Authors: GROSBOIS MICHÈLE
Published: April 2006

By a combination of thin‐layer chromatography and gas liquid chromatography, a complete study of the development of the different lipid classes and of their fatty acids, during the development of the fruit of Hedera helix L., the English Ivy, has been achieved. In any part of the fruit observed, at any particular stage, the phospholipids and the neutral lipids are the most abundant lipid classes. They accumulate during the entire process of maturation, whereas significant changes occur in their relative proportions, phospholipids being largely dominant until fruit blackening.

The accumulation of fatty acids during maturation is characterized by large amounts of C18:1 in the neutral lipids, especially in the seed, where petroselinic acid (C18:1Δ6) reaches 86% of the total fatty acids. To a smaller extent, the phospholipids also accumulate and thus have the character of reserve molecules. However, their composition remains more stable, which relates them to the “structural lipids” such as galactolipids that maintain their characteristic fatty acid composition, despite the radical changes occurring in the fatty acid metabolism during fruit ripening.
Callus Induction by (2‐Chloroethyl) Phosphonic Acid on Cultured Cotton Ovules
Authors: LEE HSU CECILIA , STEWART JAMES McD.
Published: April 2006

The response of cultured cotton (Gossypium hirsutum L.) ovules to the ethylene releasing growth regulator, (2‐chloroethyl) phosphonic acid (ethephon), was measured. Control ovules grown on a complete liquid medium without hormones continued the differentiation normal for cotton, although at a slower rate than in vivo. When ethephon was added to the medium, normal organ and fiber development was inhibited but callus was induced from the micropylar end of the ovule. The callus was extremely friable and produced many free cells in the culture medium. Dry weight of the callused ovules increased over 4‐fold and total cell number increased 56% over the controls. Apparently ethylene released from the ethephon stimulated both cell division and cell expansion in forming the callus.
Water Stress in Plants
Authors: RASMUSSEN OLE S.
Published: April 2006

The abscisic acid (ABA) content was determined quantitatively in the leaves from wilted and unwilted tomato plants (Lycopersicon esculentum Mill. CV. Revermun) by the use of the wheat coleoptile test and gas‐liquid chromatography (GLC). Plants which have received an insufficient daily water supply for 18 days showed adaptation to wilting conditions. The plants adjust to the added amount of water by regulating their water loss through transpiration. The concentration of ABA was not higher in the leaves of plants adapted to water stress than in plants that were watered abundantly. Wilted detached leaves and leaves from rapidly wilted intact plants showed the well‐known reaction by increasing the ABA level. A possible role of ABA in the early stages of the adaptation process is discussed.
Properties of Phenylalanyl‐tRNA Synthetase and Phenylalanine Ammonia‐lyase of Pine Suspension Cultures
Authors: COWLES JOE R. , FOWLER JO ANN
Published: April 2006

Phenylalanyl‐tRNA synthetase and phenylalanine ammonia‐lyase activities were demonstrated in partially purified extracts of pine (Pinus elliottii) suspension cultures. The optimum pH for the phenylalanyl‐tRNA synthetase reaction was 7.5 and the optimum ATP and Mg2+ concentrations were 1.0 and 15 mM respectively. Pine, calf liver and yeast tRNA were inadequate substitutes for pea tRNA in the synthetase reaction mixtures. The optimum pH for the phenylalanine ammonia‐lyase reaction was 9.0. The Km for phenylalanine was approximately 6.6 × 10−5M. The activity of both enzymes in the partially purified extracts was unstable on storage.
Nitrate Reductase and Nitrite Reductase Activity in Dark‐Grown Radish Seedlings: Relation to the Supply of NADPH
Authors: STULEN INEKE , LANTING L.
Published: April 2006

Functioning of nitrate reductase and nitrite reductase was measured in intact cotyledons from radish seedlings (Raphanus sativus L.) grown in the dark in a nitrate medium. Reduction of nitrate to nitrate did proceed during the whole period of 45 h, whereas the reduction of nitrite in the intact cotyledons dropped abruptly between 20 and 23 h after exposing the roots to nitrate.

The activity of the enzymes glucose‐6‐P dehydrogenase (G6PDH) and 6‐P‐gluconate dehydrogenase (6PGDH), measured in cotyledon extracts, showed a sharp decline simultaneously with the drop in nitrite reductase activity of the intact cotyledons. It was concluded that the amount of NADPH generated by the enzymes G6PDH and 6PGDH is not sufficient to allow continuous functioning of nitrite reductase after 20 h in cotyledons of seedlings grown in the dark. Therefore, the results from our experiments point to the functioning of nitrite reductase as the rate limiting step in the reduction pathway of nitrate in the dark.
Enhancement by Low pH of Gibberellin Effects on Dormant Celery Seeds and Embryoless Half‐Seeds of Barley
Authors: PALEVITCH D. , THOMAS T. H.
Published: April 2006

The action of gibberellins on celery (Apium graveolens L.) seed germination and the release of reducing sugars from barley (Hordeum vulgare L.) seed endosperm were enhanced by decreasing the pH of the incubation solution to below the pKa point. In most cases, low pH was obtained by mixing the solution with weak acids such as succinic acid 2.2 dimethylhydrazide (SADH), 2‐chloroethylphosphonic acid (CEPA), or citric acid. However, lowering the pH of the gibberellin solution with strong acid (HCl) also increased markedly the activity of low concentrations of GA4/7. The synergistic action of ethylenediaminetetraacetic acid (EDTA) with gibberellin was not dependent on the pH level of the incubation solution. The response of celery seeds to gibberellins was increased when their distal ends were removed: solution pH and EDTA had no effect on this response.

The possible explanations of the synergism between low pH compounds and gibberellins are discussed.
Temperature Response and Effect of Ca2+ and Mg2+ on ATPases from Roots of Oats and Wheat as Influenced by Growth Temperature and Nutritional Status
Authors: KÄHR M. , MØLLER I. MAX
Published: April 2006

Activation by Ca2+, Mg2+, Zn2+, or Mn2+ of adenosine triphosphatases in a microsomal fraction from wheat roots depends upon the growth temperature when the plants are grown under low salt conditions, but not when the plants get a full‐strength culture medium. At low ionic strength, cultivation at 25°C gives only half as high activation as cultivation at 18°C or at high ionic strength at both temperatures.

Corresponding data for activation of ATPases from oats also show that low ionic strength during growth gives the highest temperature dependence. Low temperature together with low salt conditions during growth gives the highest ATPase activity after stimulation with divalent cations. High growth temperature and full‐strength medium decrease the ATPase activity.

Activation energies (Ea) were calculated for the two temperature intervals 35–20°C and 20–5°C. The dominating ATPase stimulation (Ca2+ in wheat, Mg2+ in oats) is characterized by high specific activity combined with a low Ea value.

The differences in ATPase activity between oats and wheat can be correlated with different cultivation requirements known from agriculture.
Variations in Zinc Content of Subcellular Fractions from Young and Old Roots, Stems and Leaves of Broad Beans (Vicia faba)
Authors: POLAR E.
Published: April 2006

65Zn labelled seeds of broad beans (Vicia faba L.) germinated and grown in a complete nutrient solution containing the radioisotope were used to investigate the change in the subcellular distribution of this trace element during subsequent development of the labelled seeds. Homogenates of leaves, stems and roots were fractionated into cell‐wall debris, nuclei, chloroplasts, mitochondria, ribosomes and “soluble” fraction. The concentration of the radioisotope in these fractions, expressed as cpm/mg dry weight, was highest in the soluble fraction and in the ribosomes isolated from young tissues. However, as roots and leaves aged, a general decrease in the overall zinc concentration was followed by a similar drop in the concentration of the metal associated with the “soluble” fraction and ribosomes, causing a more or less uniform zinc distribution pattern. On the other hand, there was a general increase in the zinc concentration of the “soluble” and in the particulate fractions of relatively high sedimentation coefficient from older stem samples. Taking also into consideration the dry weight change per unit volume of the tissues under investigation, the relationship between these variations and the metabolism of the plant is discussed.
Anaerobic ATP Levels in the Blue‐Green Alga Anabaena: Dark‐Light Transients and Effects of Light Intensity
Authors: IMAFUKU HIROSHI
Published: April 2006

An enzymatic method was used to determine ATP extracted from anaerobically incubated samples of the blue‐green alga Anabaena variabilis. The dark‐light‐dark transients of the ATP level in the whole cells were studied in the presence and in the absence of 3 (p‐chlorophenyl)‐l.l‐dimethylurea (CMU). When O2 evolution was completely inhibited by CMU, there was no significant difference between the transient under illumination of a low intensity and that of fourfold intensity. On the other hand in the absence of CMU, the ATP level decreased more rapidly after high intensity illumination than after low intensity one. The increase in ATP content during the first 5 s illumination was smaller in the absence of CMU than in the presence of CMU. With or without CMU the increase was saturated at the vicinity of the intensity at which photosynthetic O2 evolution compensates for respiratory O2 consumption. The calculated quantum requirement of cyclic photophosphorylation in vivo was 2.2 quanta per ATP.
Étude conductimétrique des effets de trois auxines sur un parenchyme de réserve
Authors: MEYLAN S.
Published: April 2006

Conductimetric study of the effects of three auxins on a storage tissue.

The change of conductivity of calibrated disks of potato tuber tissue was measured after a 6 h immersion in a mixed aqueous solution of 1 × 10−3M auxin and 0.2 M mannitol, or pure auxin, or mannitol, of the same concentrations; then measured anew after a l h immersion in 0.1 M KCI. The auxins used were: β‐indolyl‐acetic acid (AIA), α‐naphtyl‐acetic acid (ANA) and β‐naphtoxyacetic acid (ANOX). A final higher conductivity was observed, the effect increasing from AIA to ANA and ANOX. The physiological significance of the results is discussed.
Apical Growth Cessation and Shoot Tip Abscission in Salix
Authors: JUNTTILA OLAVI
Published: April 2006

Time course of apical shoot growth and shoot tip abortion in northern ecotypes (lat. 69°39′N, long. 18°37′E) of Salix pentandra and S. caprea have been investigated. In trees more than 15 years old growing under natural climatic conditions apical growth cessation and shoot tip abortion normally occurred in June‐July when the day length still was 24 h. Application of GA3, in spring to the apex effectively delayed growth cessation and shoot tip abortion. Application of kinetin was without effect. First‐year seedlings of both species grew continuously at temperatue of 9 to 24°C in 24 h photoperiod. Short days induced apical growth cessation, but two to four (S. pentandra) or three to five (S. caprea) weeks of 12 h photoperiod were required to stop the elongation growth. The results indicated that the critical photoperiod for apical growth cessation in the used ecotype of S. pentandra was 16 to 18 h at 18°C. Short days had a minor effect only on the formation of apical leaf primordia in small seedlings. Development of axillary buds and radial growth were stimulated by short days when compared with long days. Small seedlings of both species (3 to 8 cm high at the start) formed terminal buds in short days, but in large seedlings (more than about 15 cm high) apical growth cessation was accompanied by shoot tip abortion. Abscisic acid applied to the apex or through a leaf did not induce growth cessation in S. pentandra seedlings grown in continuous light. The growth retardants CCC, B‐9 and Phosphon D reduced growth rate under continuous light and induced shoot tip abortion in some plants. The effect of CCC was counteracted by GA3. Apical growth cessation in short days was significantly delayed by a single GA1 application.
Nitrogen and Cation Nutrition of Three Ecologically Different Plant Species
Authors: INGESTAD TORSTEN
Published: April 2006

Experiments on nutrient requirements of the ecologically very different plant species Betula verrucosa Ehrh., Cucumis sativus L., and Vaccinium vitis idaea L. are discussed with regard to the nitrogen and cation nutrition. The nutrient solution technique used allows a strict control of nitrogen source and cation uptake at maximum growth rate.

The nitrogen sources were equally efficient except for growth reductions in cucumber at ammonium nutrition. Increase in tissue pH resulting from a high total uptake rate of NH4+ and other cations is probably an important factor in ammonium toxicity. No evidence was found for the concept of “ammonium plants”; but at high nitrate supply to Vaccinium a high cation uptake may account for decrease in growth rate.

No large or fundamental differences in cation or anion requirements among the species were found; the difference in ion balance (C — A) in relation to dry matter depends mainly on differences in xeromorphy.

In cucumber, the relations between cation and nitrate nutrition are in agreement with models proposed in the literature. Vaccinium and birch have a cation uptake and retention of high efficiency at low nutrient availability and ammonium nutrition indicating independence between cation and nitrate nutrition in these species.

The properties found are regarded as significant and functional in relation to the ecological character of the species.
Uptake of 14C‐L‐Glutamic Acid by Daucus carota Cell Suspension in Different Shock Situations
Authors: WAHLSTRÖM DAN , ERIKSSON TAGE
Published: April 2006

Cell suspension cultures of Daucus carota were shocked by inoculation or by temperature, salts or osmotica in combination with inoculation. Changes in cell vitality were measured by uptake studies with labelled L‐glutamic acid performed during the first 30 min after shock treatment. The cell sample was then collected on filter and counted in a liquid scintillation counter. Inoculation alone caused a marked decrease in uptake. Normal uptake capacity was re‐established within 2 h. Temperatures of 0−20°C as against 27°C gave an additional decrease in uptake. Of the tested osmotica, polyethylene glycol gave the greatest stabilizing effect on the glutamic acid uptake and sucrose the least. The highest uptake rates were obtained with a calcium concentration of 0.10–0.15 mM.
Effects of 2,5‐Dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone (DBMIB) on Light Induced and Glycolytic Phosphate Uptake in Scenedesmus
Authors: SUNDBERG INGRID , TILLBERG JAN‐ERIC , BJÖRKLUND GUN
Published: April 2006

The effects of DBMIB on photophosphorylation and glycolysis in Scenedesmus obtusiusculus Chod. were investigated by measuring the uptake of inorganic phosphate. To analyze the effects of DBMIB on the different energy coupling possibilities in open chain and cyclic photophosphorylation, DBMIB was given to the algae in narrow concentration intervals between 10−6M to 10−4M, either alone, or in combination with DCMU (3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea) or desaspidin. DBMIB inhibits non‐cyclic as well as cyclic photophosphorylation in Scenedesmus. However, the DCMU resistant photophosphorylation reactions are less sensitive to DBMIB than the open chain photophosphorylating system in non‐DCMU treated cells. Low concentrations of DBMIB even released a part of the DCMU inhibition. Experiments with combinations of DBMIB and desaspidin also indicated that cyclic photophosphorylation is less sensitive to DBMIB than non‐cyclic. The inhibition of DCMU resistant cyclic phosphorylation by DBMIB, which is a competitive inhibitor of quinones, indicated a participation of plastoquinones in this type of energy coupling as well as in the non‐cyclic and DCMU‐sensitive processes. The cyclic and the non‐cyclic photophosphorylation pathways probably use different parts of the plastoquinone pool.

For the purpose of the experiments, it was necessary to produce data for the effect of DBMIB (10−6–10−4M) on glycolysis. The highest concentration gave 50% inhibition.
Variations nycthémérales de l'intensité des corrélations entre les cotylédons et leur bourgeon axillaire induites par des traumatismes faits unilatéralement sur l'un des deux cotylédons de Bidens pilosus
Authors: DESBIEZ MARIE‐ODILE
Published: April 2006

Different methods (physiological, electrophysiological and biochemical) were used in order to show, during a 24 h period, a change in sensitivity of Bidens pilosus seedlings to the pricking of one of the cotyledons. The sensitivity is maximum in the morning and in the evening; it decreases during the light period (day) and the dark period (night). The minimum of the sensitivity occurs in the middle of the day and 3 to 4 h after the beginning of the night.