bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ethylene on the Qualitative and Quantitative Composition of the Phenol Content of Carrot Roots
Authors: SARKAR SUBODH K. , PHAN C. TON
Published: April 2006

Carrot (Daucus carota L.) roots stored at 3 ± 1°C in an atmosphere containing 100 μ1/I of ethylene had their total phenol content increased markedly as compared to control samples kept in air. The increase was two‐fold: i. higher level of pre‐existing phenols, particularly isochlorogenic acid, ii. de novo synthesis of (at least) four compounds, two of which were identified as 3‐methyl‐6‐methoxy‐8‐hydroxy‐3,4‐dihydroisocoumarin, and 5‐hydroxy‐7‐methoxy‐2‐methylchromone, which are not normally present in carrot tissues.
Esterification and Spectral Shifts of Chlorophyll(ide) in Wildtype and Mutant Seedlings Developed in Darkness
Authors: HENNINGSEN K. W. , THORNE S. W.
Published: April 2006

Spectral changes and esterification (presumably with phytol) of newly formed chlorophyllide a in dark‐grown leaves of wildtype bean (Phaseolus vulgaris) and barley (Hordeum vulgare) and a number of chloroplast mutants in barley, were studied by spectrofluorimetry on leaves and on solvent extracts.

The shift of the fluorescence emission maximum from 692–694 to 678 nm (excitation shift: 682–684 to 672 nm) and esterification of chlorophyllide a have a similar time course, and both processes are temperature dependent in a similar manner. After completion of the spectral shift and esterification, the fluorescence efficiency of chlorophyll a increases with a subsequent reaccumulation of protochlorophyllide. In leaves of mutants where the shift of fluorescence from 692 to 678 nm is lacking, esterification and the subsequent processes are also blocked. In leaves of mutants with a rapid shift of the fluorescence from 692 to 678 nm, or with direct photoconversion to chlorophyllide a with the fluorescence at 678 nm, esterification is also rapid.

The results are interpreted as a sequence of molecular events involving a conformational relaxation of the chlorophyllide holochrome and a translocation of chlorophyll a to reaction centers of the photosystems.
The Effect of Auxin and Low pH on Young's Modulus in Pisum Stems and on Water Permeability in Potato Parenchyma
Authors: UHRSTRÖM INGER
Published: April 2006

The effect of auxin and acid solution on Young's modulus (E) and longitudinal growth has been studied on growing segments of Pisum sativum. The modulus has been determined by means of the resonance frequency method. 2.8·10−5M IAA produces a decrease in E within 4 minutes and an increase in length in about 7 minutes. A 10−4M HCl‐solution produces an almost immediate decrease in E and increase in length. The response to the acid solution only persists for about 10 minutes whereas the auxin response continues for hours. Therefore, it is improbable that the hydrogen ions activate a normal enzymatic process leading to increased elasticity and growth. Further the water permeability in potato parenchyma has been investigated by means of the resonance frequency method. Auxin as well as hydrogen ions increase the water permeability, auxin within 2 minutes and hydrogen ions immediately. The lag of the increase in permeability in the auxin solution and the immediate response in the acid solution indicate that auxin and hydrogen ions do not act in the same way, even if an increased membrane permeability is the most probable explanation in both cases. It is suggested that the hydrogen ions act directly on the membrane by changing the membrane potential and thus the permeability, whereas auxin may increase the proton concentration in the membrane enzymatically and thus change the permeability.
pH Changes Associated with Iron‐Stress Response
Authors: BROWN J. C. , JONES W. E.
Published: April 2006

When Fe‐inefficient T3238fer and Fe‐efficient T3238FER tomatoes were supplied iron, and nitrogen as nitrate, they increased the pH of the nutrient culture. When they were supplied nitrogen as ammonium, they decreased the pH. When Fe supply was limited, Fe‐stress response developed in T3238FER that opposed the usual nitrate response and decreased, rather than increased, the pH. A “reductant” which reduced Fe3+ to Fe2+ was released from the roots of these plants and lowered the pH; and there was a tremendous increase in the uptake of Fe. T3238fer did not produce “reductant” in response to Fe‐stress; the pH increased, and the plants developed Fe‐deficiency when nitrogen was supplied as nitrate. Nitrogen nutrition and iron‐stress response are important factors associated with iron chlorosis in plants. Release of hydrogen ions from roots of Fe‐stressed plants is caused by more than response to imbalanced uptake of cations and anions.
Root Formation in Pea Cuttings
Authors: ERIKSEN E. NYMANN , MOHAMMED SHAFAAT
Published: April 2006

Cuttings were either decapitated or both decapitated and disbudded at different time intervals. Auxin, at different concentrations, was applied to the cuttings in lanoline.

Auxin applied to decapitated and disbudded cuttings promoted root formation in the early stage of the initiation phase.

Auxin treated cuttings, which were only decapitated, did not show an increase in number of roots per cutting. However, an increase in the root mass was found in the early stage of the initiation phase.

The results seem to indicate that auxin is active only in the first part of the initiation phase. It is acting alone, not together with other substances synthesized in the shoot meristem.
Effect of Auxins, Cytokinins, Gibberellins, Abscisic Acid and Ethephon on Regeneration and Growth of Bulblets on Excised Bulb Scale Segments of Hyacinth
Authors: PIERIK R. L. M. , STEEGMANS H. H. M.
Published: April 2006

The effect of various growth substances on regeneration and growth of bulblets on excised bulb scale segments of Hyacinthus orientalis L. cv. Pink Pearl was studied. Bulblet formation was promoted by the auxins IAA and IBA but was inhibited by NAA at high concentrations. IAA hardly affected bulblet weight, whereas IBA and NAA at high concentrations decreased it. Cytokinins had hardly any effect on bulblet regeneration and bulblet weight, Gibberellins inhibited both bulblet regeneration and bulblet weight; GA4+7 acted much stronger than GA3. ABA and ethephon decreased bulblet regeneration and bulblet growth.
Changes Induced in Peroxidase Activity under Simulated Hypo‐gravity
Authors: WABER J. , WILLIAMS B. J. , DUBIN J. , SIEGEL S. M.
Published: April 2006

A new method of inducing and maintaining a hypo‐gravity environment is described. Using this new technique (buoyancy compensation), the effect of reduced gravitational stress on dwarf marigolds (Tagetes patula) was studied. It was found that the specific activity of peroxidase was elevated significantly in gravity compensated seedlings. This effect, discovered with the buoyancy compensators, was confirmed with plants grown on traditional clinostats.
Ethylene Evolution Stimulated by Succimc Acid‐2,2‐Dimethylhydrazide in Apple Shoots
Authors: JINDAL K. K. , ANDERSEN A. SKYTT , DALBRO S.
Published: April 2006

The rate of ethylene production in the shoot tips of the apple cultivar ‘Ingrid Marie’ (Red motant) after succinic acid‐2,2‐dimethylhydrazide (SADH) treatment was investigated. The shoots were treated with SADH at 12.5, 25 or 50 mM in the months of June, July and August. The samples were analysed 7,15, 30 and 60 days after SADH spray.

Ethylene production was considerably higher in the SADH‐treated shoots than in the untreated ones. Application of 12.5 or 25mMSADH late in June stimulated ethylene production 3‐fold, while 50 mM produced a 5‐fold increase in ethylene production 7 days after spraying. There was a continuous decrease in ethylene production at the subsequent samplings. In untreated control shoots there was a slight increase. However, even 60 days after spraying the shoots treated with 50 mM had higher ethylene production than the control shoots. The same relationship was found in the shoots treated in the months of July and August. A parallelism has been established between the rate of ethylene production and growth retardation, A residual effect of SADH treatment in earlier years was demonstrated and is discussed.
Changes in Endogenous Plant Hormones in Cherry Tomato Fruits during Development and Maturation
Authors: ABDEL‐RAHMAN M. , THOMAS T. H. , DOSS G. J. , HOWELL L.
Published: April 2006

Hormonal extracts of cherry tomato fruits (Lycopersicon esculentum Mill.) cv. Small Fry at different stages of fruit development and maturation were bioassayed for their auxin, gibberellin, cytokinin and growth inhibitor activities. In general, the levels of endogenous growth promoters were much higher in the young developing fruits than in the more mature fruits. Free cytokinin levels were highest in the first two weeks of development then declined rapidly. However, cytokinin activity in the ribotide fraction, after treatment with alkaline phosphatase, decreased during thefirst three weeks of development then increased rapidly over the following four weeks. Auxin levels increased during early development to reach a maximum in three‐week‐old fruits after anthesis. Gibberellin levels during the first two weeks of development were much lower than those of auxins and cytokinins, but then increased to reach a peak in the fourth week after anthesis.

A growth inhibiting substance with Rf similar to that of abscisic acid was found in the acidic fraction of the fruit extracts. This inhibitor increased gradually during fruit growth and development and reached a peak at the age of five weeks which coincides with the green mature stage.
Rôle des polyphénols dans la croissance. Définition ?un modèle expérimental chez Lycopersicum esculentum
Authors: MARIGO GÉRARD , BOUDET ALAIN M.
Published: April 2006

Using young plants of Lycopersicum esculentum Mill., we attempt to define a system for a new evaluation of the physiological role of polyphenols, particularly of their regulating properties on growth and development, Exogenously supplied qoinic acid causes an important increase of the phenolic content and a reduced growth of the plants.

The decrease in size is proportional to the stimulation of the phenolic pool and is equally obtained using other precursors of aromatic compounds like phenylalanine and cinnamic acid. Non‐precursors of polyphenols structurally related to quinic acid are ineffective. It appears from these data that polyphenol levels and growth could be related in tomato plant and that this material would be convenient for studies on interactions between growth and polyphenols.
Protein Synthesis in Plant Microsomal System
Authors: DUBE SYAMALIMA , DUBE D. K. , GOSWAMI BISWENDU B. , ROY S. C.
Published: April 2006

An active microsomal system from 48‐h germinating seeds of Vigna sinensis (L.) Savi has now been developed. It can incorporate amino acids into protein under both in vitro and in vivo conditions, provided dithiothreitol (a protective reagent for SH groups) and phenylthiourea (an inhibitor of phenol oxidase) are present in the buffer system for extraction; and provided the assay mixture contains added dithiothreitol.

The system consists of microsomes or ribosomes, tRNA or pH 5 fraction and 20 natural amino acids, ATP and an ATP‐generating system and GTP with requirement for Mg ions. The cell fractions possess aminoacyl‐RNA synthetase activity as indicated by the aminoacylhydroxamate formation. Microsomal synthesis is stimulated by exogenous tRNA from Escheriehia coli or rat liver and sensitive to various inhibitors such as cyclo‐heximide, chloramphenicol, fusidic acid. The ribosomal transfer reaction has absolute dependence on the microsomal wash, on the crude enzyme from the same participate source, and on a synthetic messenger. It is greatly suppressed by fusidic acid and by cycloheximide.
Regulation of Prenyl Chain Synthesis in Etiolated Hordeum Seedlings by Far‐Red and White Light
Authors: LICHTENTHALER HARTMUT K.
Published: April 2006

The kinetics of prenyl chain formation (C20 phytyl in chlorophylls, vitamin KI and α‐tocopherol; C40 carotenoids and C45 in plastoquinone‐9) in plastids of etiolated Hordeum seedlings was compared in continuous darkness and after far‐red and white light treatments:

Continuous far‐red (via phytochrome Pfr) enhances the synthesis rate of all prenyl chains, but does practically not change the dark pattern of prenyl chain accumulation. Free C20 phytyl chains could not be detected by means of thin layer chromatography.

White light induces a much stronger enhancement of prenyl chain formation than does far‐red. It also changes the pattern of prenyl chain synthesis by a particularly strong promotion of the synthesis of phytyl chains, which get bound to chlorophyll a. The rate of chlorophyllide formation seems to determine the rate of enhanced phytyl formation.

It is assumed that the enzyme, which esterifies chlorophyllide a with the phytyl chain, is formed or activated by far‐red treatment, but only starts working in white light, when the protochlorophyllide holochrome is re‐arranged to the chlorophyllide holochrome.
Preferential Assimilation of Ammonium Ions from Ammonium Nitrate Solutions by Apple Seedlings
Authors: FRITH G. J. T. , NICHOLS D. G.
Published: April 2006

Apple seedlings, Pyrus malus L., were grown in complete nutrient solutions containing nitrate, ammonium, or ammonium plus nitrate as the nitrogen source. Uptake of nitrogen was calculated from depletion measurements of the nutrient solutions and by using 15N labelled nitrate and ammonium salts.

If the plants received nitrogen as ammonium only or as nitrate only, the amounts of nitrogen taken up were similar. However, if the seedlings were supplied with ammonium nitrate, the amount of nitrate‐nitrogen assimilated was only half that of ammonium. Nevertheless, if ammonium and nitrate were supplied to a plant with a split‐root system, with each root half receiving a different ion, the uptakes were similar.

The possibility of independent inhibition by ammonium of both nitrate uptake and reduction in the roots is discussed.
Physiological Changes of Carrot Cells in Suspension Culture during Growth and Senescence
Authors: OKAMURA S. , SUEKI K. , NISHI A.
Published: April 2006

Changes in the synthetic activities of nucleic acids and protein and in the amount of adenine nucleotides in Daucus carota cells have been examined during a period of rapid cell division and during the stationary phase. Cell growth and the syntheses of those macromolecules in the logarithmic phase were significantly enhanced by increasing the concentration of phosphate in the medium. In a phosphate‐rich medium, RNA and protein rapidly degraded and the number of cells with denatured cytoplasm increased when the culture entered into a stationary phase because of exhaustion of glucose. On the other hand, when the growth ceased by exhaustions of phosphate and nitrogen, the cells slowly underwent physiological changes leading to cellular senescence. The value of adenylate energy charge during the growth period was about 0.8–0.9 irrespective of the growth rate. After cessation of growth the value declined to about 0.5.
Activities of Two Peptidases in Resting and Germinating Seeds of Scots Pine, Pinus sylvestris
Authors: SALMIA M. AULIKKI , MIKOLA JUHANI J.
Published: April 2006

Extracts prepared from resting seeds of Scots pine, Pinus sylvestris L., rapidly hydrolysed two peptides, Leu–Tyr and Ala–Gly, at pH 8.6 and 7.8, respectively. In gel chromatography on Sephadex G‐100 the two activities were eluted as separate peaks, which indicates that they are due to two different peptidases.

The seeds were allowed to germinate at 20°C, the activities of the two enzymes were assayed separately on extracts from the endosperm and seedling tissues at different stages of germination, and compared with corresponding changes in dry weight and total nitrogen. Both enzyme activities were relatively high in the endosperm of resting seeds, and they increased about 2‐ and 3‐fold during germination (expressed as enzyme units per seed), the increases coinciding with the time of rapid reserve protein mobilization. Both enzymes were also abundant in the embryos of resting seeds, and during germination their activities increased even more rapidly than those in the endosperm.

The possible role of these two “alkaline peptidases” in reserve protein hydrolysis is discussed.
Influence of Light on the Bioelectric Potential of the Bean (Phaseolus vulgaris) Hypocotyl Hook
Authors: HARTMANN ELMAR
Published: April 2006

By use of surface electrodes electropotenlial measurements were carried out on hypocotyl hooks of Phaseolus vulgaris seedlings. The hooks were illuminated with a small spot of white, blue, red or far red light.

The potential changes in bean hypocotyl hooks do not show the red‐far red reversible characteristics of phytochrome‐mediated processes. By experimenting with inhibitors of photosynthesis we could demonstrate that the light‐triggered potential changes in green bean hooks are correlated to photosynthetic electron transport phenomena. The red‐light‐induced transient is a depolarization, whereas blue light induces a hyperpolarization. Etiolated beans exhibit no bioelectric potential changes when subjected to red or far red irradiations. Blue light and white light induce a strong hyperpolarization in etiolated hooks cells. This transient seems to be an action potential induced by light. The action potential is influenced by inhibitors of electron transport and oxidative phosphorylation. By comparing the action spectrum of the action potential induced by light with the absorption spectra of extracted carotenoids and xanthophylls from etiolated bean hypocotyl hooks, we observed similarities.
Cell Wall Solubilization in Pedicel Abscission of Begonia Flower Buds
Authors: GATE CH. H. HÄNISCH TEN , VAN NETTEN J. , DORTLAND J. F. , BRUINSMA J.
Published: April 2006

Effects of metabolic inhibitors and growth regulators on the course of abscission and on the activities of cell wall solubilizing enzymes were studied in pedicel explants of Begonia flower buds.

Actinomycin D, chloramphenicol and 2,4‐dinitrophenol slightly retarded abscission, whereas cycloheximide exerted a strong inhibition if applied until 10.5 h after explant excision.

Indoleacetic acid retarded and ethylene promoted abscission and cell wall solubilization. However, the activities of cell wall solubilizing enzymes did not correspond with the course of abscission. No polygalacturonase and pectic acid and pectin transeliminases could be detected in the abscission zone during abscission, whereas a low pectin methylesterase activity did not change. Endo‐ and exocellulase activities did not increase until about 10 h after the onset of abscission, indicating that they are the result rather than the cause of abscission.
Metabolite Concentrations and Phase Relations in d‐Fructose Induced Glycolytic Oscillations
Authors: BETZ A. , BECKER J.‐U.
Published: April 2006

The frequency of glycolytic oscillations in yeast cells is only slightly modified by the consumption rate of either glucose or fructose, but it is reduced to 1 /2 to 2/3 if the ketohexose is the only substrate.

Phase relations between NADH, adenine nucleotides and sugar phosphates (G‐6‐P, F‐6‐P, FDP, DAP) are independent of the hexose fermented.

With fructose as a substrate the amplitudes of adenylates and hexose phosphates are distinctly smaller than with glucose. The maximum of G‐6‐P is higher with glucose and the minimum concentration of FDP is higher with fructose.

In the transition to anaerobiosis FDP, adenosine 5′‐diphosphate and adenosine 5′‐phosphate are extremely high, whereas G‐6‐P, F‐6‐P and ATP concentrations are lower if fructose is the substrate fermented.

The results are indicative for different control characteristics of the phosphofructokinase step, but on their basis it cannot be distinguished between a direct interaction of fructose (or one of its derivatives) on the phosphofructokinase kinetics or the existence of a bypass for fructose which might be able to withdraw a part of the substrate from the control point at the phosphofructokinase.
Photoassimilation of CO2 by Isolated Bundle‐Sheath Strands of Zea mays I. Stimulation of CO2 Assimilation by Adding Various Intermediates of the Photosynthetic Cycle; Evidence for a Deficient Photosystem II Activity
Authors: FARINEAU JACK
Published: April 2006

Isolated bundle‐sheath (BS) strands from leaves of mature maize plants show enhanced rates of CO2 fixation in the presence of reduced intermediates of the photosynthetic cycle (R5P, DHAP, FruDP.) 3PGA is the major labelled product of 14CO2 fixation whatever the substrate added. CO2 fixation is much lower with PGA than with reduced intermediates, suggesting a limited capacity of the cells to regenerate RuDP (the CO2‐acceptor) from PGA. These two experimental facts, which are characteristic features of bundle‐sheath photosynthesis for maize (a species with agranal bundle‐sheath chloroplasts) indicate that phaotosystem II activity is a limiting factor for the evolution of the bundle‐sheath photosynthetic process. Nevertheless, a reducing capacity arises as proved by sensitivity of CO2 fixation to DCMU, particularly when PGA is added to the bundle‐sheath.

PGA synthesis occurs, in the presence of non‐limiting amounts of CO2, according to the equation: RuDP + CO2→ 2 PGA; the oxygen effect on 14CO2 fixation, at lower CO2 concentration, is interpreted as a dilution effect of the internal pool of 14CO2 by unlabelled CO2 generated by photorespiration.
Photoassimilation of CO2 by Isolated Bundle‐Sheath Strands of Zea mays
Authors: FARINEAU JACK
Published: April 2006

The role of malate decarboxylation as a source of CO2 and NADPH for the evolution of photosynthesis of isolated maize bundle‐sheath strands has been investigated. The bundle‐sheath cells were supplied with malate plus NADP, in the presence of intermediates of the Calvin cycle to increase the rate of CO2 fixation.

The effects of malate addition on the rate of 3 phospoglycerate synthesis, with non‐saturating concentrations of bicarbonate, can be explained by an increase of the cellular pool of CO2 in the cells due to malate decarboxylation. The CO2 reacting with RuDP to give phosphoglycerate corresponds effectively to carbon atom 4 of malate. Malate addition produces an enhancement of the rate of CO2 incorporation which is much more important when the reducing power is the limiting process for the evolution of the Calvin cycle (with phosphoglycerate as added substrate and/or in the presence of DCMU. These results demonstrate the utilization of NADPH produced by malate decarboxylation for the regeneration of RuDP. NADPH can also reverse the reaction of malate decarboxylation and gives rise to a synthesis of malate by carboxylation of pyruvate.

In contrast, the pattern of 14C distribution among compounds is not strongly modified by malate addition. This result suggests that PGA reduction in the whole leaf must occur also in mesophyll cells to allow correctregeneration of the reduced compounds of the photosynthetic cycle.
Isolation and Partial Characterization of Globoids from Aleurone Grains of Arachis hypogaea Seed
Authors: SHARMA CHANDRA B. , DIECKERT JULIUS W.
Published: April 2006

The aleurone grains of the peanut (Arachis hypogaea) have been fractionated into the globoidal and nongloboidal components by homogenization in 0.5 M sucrose solution and differential centrifugation. The major components of the globoids are: protein, 35.1%; magnesium, 2.5%; potassium, 2.0%; myoinositol, 7.0%; total phosphorus, 7.4%; oxalic acid, 3.5%; and moisture, 8.6%. Small amounts of calcium (0.5%) and manganese (0.03%) are also present. Of the total phosphorus about 97% is present as organic phosphorus of which phytic acid (myoinositol hexaphosphoric acid) constitutes the major portion with only 0.1% orthophosphate and traces of lower phosphates of myoinositol. The globoidal fraction accounts for about 50% of the total magnesium, manganese, phytic acid, oxalic acid, and for 13% of the potassium and 80% of the calcium present in the aleurone grains. The remainder of these components are present in the matrix of the aleurone grain. There seems to be a cation deficit in the globoids and a cation excess in the aleurone grains and soluble fraction. The nature of the missing cation in the globoid and the missing anion in the aleurone grain or in the soluble fraction was not determined, but thought to be protein.
Uptake by Yeast: Interaction of Rb+, Na+ and Phosphate
Authors: BORST‐PAUWELS G. W. F. H. , THEUVENET A. P. R. , PETERS P. H. J.
Published: April 2006

It has been shown that addition of phosphate to phosphate deficient yeast gives rise to an immediate increase in the rate of Na+ uptake and an immediate decrease in the rate of Rb+ uptake. In addition, phosphate uptake is enhanced specifically by Na ions presumably by a process with a very high affinity for phosphate with a Km of about 2 × 10−6M at pH 7.2, whereas the Km for phosphate uptake of the Na+ independent process amounts to 1.3 × 10−4M.
Changes in Nitrogenous Compounds and Proteases during Germination of Vigna sinensis Seeds
Authors: PRISCO JOSÉ TARQUINIO , AINOUZ IRACEMA LIMA , MELO SIGEFRÊDO de C.
Published: April 2006

Seedling growth, protein, soluble amino nitrogen, and proteolytic activity of serido beans (Vigna sinensis) were studied during the first 6 days of germination. Cotyledon dry weight decreased constantly with germination time, reaching at the 6th day 27% of the weight it had at day 0. Embryo‐axis dry weight increased during the same period, amounting to 79% of the total weight of the seedling at the 6th day of germination. Cotyledon proteins increased slightly during the 1st day of germination and then decreased until the end of the experimental period. Cotyledonary soluble amino nitrogen stayed constant for the 1st day of germination, increased up to the 3rd day, and then fell steadily until the 5th day. Embryo‐axis soluble amino nitrogen followed the same pattern as the embryo‐axis proteins, that is, a slight increase during the first 3 days, a pronounced increase from the 3rd to the 5th, and a leveling off from this day on. Proteolytic activity was studied at pH 3.5 and pH 6.0. Both proteases increased in activity during the first 3 days of germination, at which point they reached their maximum activities. From this day on their activities fell continuously, reaching on the 6th day values slightly higher than those of day 0. These observations appear to indicate that contrary to pea cotyledon proteases, serido bean protesaes are intimately associated with reserve protein degradation.
Allelopathy in Heracleum laciniatum: Inhibition of Lettuce Seed Germination and Root Growth
Authors: JUNTTILA OLAVI
Published: April 2006

Both dark and red light germination of lettuce seeds (cv. “Maikönig”) as well as their root and hypocotol elongation were inhibited when the seeds were sown in petri dishes together with a few seeds of Heracleum laciniatum Horn. This inhibition was not significantly counteracted by the presence of gibberellic acid (GA3) or/and 6‐benzylaminopurine (BA). However, a large proportion of the lettuce seeds germinated abnormally (only cotyledons emerged) when treated with BA in the presence of Heracleum seeds. GA3 had alone no significant effect on abnormal germination, but it counteracted the effect of BA to some extent.

The inhibitory effect of Heracleum seeds gradually disappeared during a moist incubation period of one to seven days in darkness at 25°C.

When lettuce seeds were pre‐incubated together with Heracleum seeds for one to five days the remaining, non‐germinated lettuce seeds had lost their ability for subsequent germination in darkness in distilled water. This induced dark dormancy was to a great extent broken by red light, but not by GA3 or/and BA.

H. laciniatum seeds inhibited the germination of Salix pentandra seeds and to some extent also the germination of radish but had no effect on the germination of spruce.
Changes in Some Enzyme Activities and Respiration in the Early Stage of Callus Formation in a Carrot‐root Tissue Culture
Authors: KOMAMINE ATSUSHI , SHIMIZU TOMIKO
Published: April 2006

The respiratory rate increased in two phases during early stages of callus formation in carrot (Daucus carota)‐root phloem slices cultured in vitro, showing separate peaks at about 24 and 96 h of culture. In the first phase (within 24 h of culture), the activities of phosphoglucose isomerase, phosphofructokinase and succinate dehydrogenase did not increase, but active syntheses of RNA and protein, indicated by experiments with incorporation of [14C]‐uracil and ‐leucine, resulted in an active turnover of ATP, to which the first increase in the respiratory rate may be attributable. On the other hand, the activity of phosphoribosylpyrophosphate synthetase, an enzyme related to nucleic acid synthesis, increased in the first 24 h of culture. In the second phase (24–96 h of culture), the activities of the respiratory enzymes investigated increased. This increase was repressed by cycloheximide, indicating de novo syntheses of the respiratory enzymes during this time, which may result in an enlargement of the respiratory capacity, to which the second increase in respiration may be mainly attributable. In the first phase, exogenous supplied 2,4‐dichlorophenoxyacetic acid had little or no effect on the respiratory rate and the activities of the respiratory enzymes, but it enhanced synthesis of RNA and the activity of phosphoribosylpyrophosphate synthetase. In the second phase, it increased all the activities of enzymes investigated as well as the respiratory rate and RNA synthesis.
Effect of Abscisic Acid on the Transpiration of Zea mays
Authors: TALHA MAHMOUD , LARSEN POUL
Published: April 2006

Intact plants of Zea mays L. were treated with foliar sprays of cis‐trans‐abscisic acid (ABA) at concentrations from 10−9 to 10−4M. Even the lowest concentration caused a reduction of the transpiration rate as measured between 1 and 33 h after spraying. With increasing ABA concentrations, there was a nearly linear relationship between the logarithm of the ABA concentration and the (decreasing) transpiration rate within that period. Subsequently a partial recovery of the transpiration rate set in, beginning progressively later as the ABA concentration was increased. After 5 1/2 days the transpiration rate of plants treated with 10−9 and 10−8M was nearly back to normal, whereas plants treated with 10−4M transpiration at only about 2/3 their normal rate.

In experiments with detached maize leaves supplied with water or ABA solutions (10−8 to 10−5M) through their cut bases, the transpiration of control leaves decreased gradually to a low level in 24 h. ABA caused a marked and rapid reduction of the transpiration rate compared to that of the controls. After a few hours, the transpiration of the treated leaves decreased at a slower rate than that of the controls, thus approaching the control values. After 35 h, the transpiration of leaves treated with 10−5M ABA was nearly the same as in untreated leaves. Exchanging the ABA solution for distilled water after 24 h had little effect on the subsequent course of the transpiration rate.
The Effect of Temperature on Growth and Mineral Nutrition of Fruits of Apple, with Special Reference to Calcium
Authors: TROMP J.
Published: April 2006

Growth and mineral composition of fruits in potted trees were studied at two temperatures (19 and 24°C) in two experiments with Golden Delicious and one with Cox's Orange Pippin under a controlled environment. In Golden Delicious the high temperature promoted fruit growth markedly, but in Cox's Orange Pippin the stimulation was much less pronounced.

The levels of K, N, Mg, and P (expressed as amounts per fruit) were increased at the higher temperature. This increase was almost completely the result of differences in fruit growth. With respect to Ca the high temperature reduced Ca influx in one Golden Delicious experiment and had hardly any effect in the other, but favoured influx in Cox's Orange Pippin. In one Golden Delicious experiment the temperature was raised 7 weeks after blossoming, which resulted in a temporary drop of Ca. When the same temperature change was applied 4 weeks earlier, Ca continued to increase.

It is assumed that mineral influx occurs via the xylem during the first few weeks after fruit set and via the phloem throughout. The results are discussed in terms of differences in mobility in the phloem for the various minerals and of a shift in the ratio between xylem and phloem movement induced by differences in the growth rate of the fruits.
Activity of Antheridiogen from the Fern Anemia phyllitidis in Three Flowering Plant Bioassays
Authors: SHARP PAMELA B. , KEITT GEORGE W. , CLUM HAROLD H. , NÄF ULRICH
Published: April 2006

Pure samples of the antheridiogen of Anemia phyllitidis (AAn) were tested for their ability to affect the growth of dwarf corn (d5) and lettuce seedlings, and to influence α‐amylase production by barley half‐seeds. Stimulation of dwarf corn growth and barley amylase production was, on a molar basis, from 1/2 to 1/250 that given by GA3. In lettuce, AAn had a synergistic effect with low levels of GA3; alone, AAn was inhibitory or ineffective. Therefore, in addition to having a close chemical resemblance to gibberellin, AAn induces similar, but not identical physiological responses in flowering plants as well as ferns.
Identification of Zeatin and Zeatinriboside in Coconut Milk
Authors: STADEN J. VAN , DREWES S. E.
Published: April 2006

Zeatin and zeatinriboside were identified from the milk of mature Cocos nucifera fruits. It would appear as if the two compounds are present in roughly equal proportions. Ethyl acetate extraction in a liquid‐liquid extractor at an alkaline pH (8.0) proved to be a very efficient method of extracting zeatinriboside. Partitioning with water‐saturated n‐butanol proved to be the best way of extracting zeatin.
Effect of Indoleacetic Acid on the Abscisic Acid Level in Stem Tissue
Authors: ELIASSON LENNART
Published: April 2006

Excised stem sections from growing plants of Populus tremula L. and Pisum sativum L. including lateral buds were treated with indole‐3‐acetic acid in a phosphate buffer solution. In control sections the level of the abscisic acid‐like inhibitor decreased strongly during 24 h as did the level of the endogenous auxin. Exogenous indoleacetic acid counteracted the decrease in the inhibitor level to a considerable extent. Implications of this auxin effect in relation to apical dominance are discussed.
Chlorophyll Accumulation, CO2 Fixation Enzymes, and Hill Activity, in Greening Roots of Lens culinaris
Authors: NATO A. , DELEENS E.
Published: April 2006

The carboxylation of ribulose‐1,5‐diphosphate was demonstrated in vitro with extracts of ctiolated seedling roots. The presence of ribulose‐1,5‐diphosphate carboxylase was characterized in the subcellular fraction enriched in amyloplasts.

Synthesis of chlorophyll, development of CO2 fixation capacities and of Hill activity upon illumination have been studied with roots of Lens culinaris seedlings. The marked increases in CO2 fixation with ribulose‐1,5‐diphosphate as the substrate and in Hill activity that occur after a lag phase seem to be related to cytological changes during the greening of roots.
Cultivation in the Dark of the Blue‐green Alga Fremyella diplosiphon. A Photoreversible Effect of Green and Red Light on Growth Rate
Authors: DIAKOFF STEPHEN , SCHEIBE JOSEPH
Published: April 2006

The blue‐green alga Fremyella diplosiphon Drouet can be grown in the dark on a medium consisting of mineral salts, glucose, and casein hydrolysate. A variety of organic substances was tested for effectiveness as a carbon or nitrogen source. The most effective individual compounds were glucose and citrulline, respectively. A daily irradiation of 5 min green light depresses the dark growth rate. The effect of green is reversible by brief irradiation with red light, and multiple photoreversibility was demonstrated.

This green, red‐reversible effect on dark growth rate may be related to other photomorphogenic responses to brief irradiation with green and red in the Cyanophyta. A master photoreversible pigment similar to phytochrome is a possible photoreceptor for these effects.
Phase Change in Hedera helix: Stabilization of the Mature Form with Abscisic Acid and Growth Retardants
Authors: ROGLER CHARLES E. , HACKETT WESLEY P.
Published: April 2006

Applications of ABA to the mature form of Hedera helix stabilize its morphological characteristics and prevent GA3 induced reversion to the juvenile form. Plants treated with GA3 reverted to the juvenile form whereas those supplied with ABA in conjunction with GA3 remained mature. When mature plants were treated with 5 nanomoles of GA3 and 5 micromoles of ABA, reversion did not occur, but when the GA3 dose was raised to 25 nanomoles with the same level of ABA, reversion did occur. This implies that the relative amounts of GA3 and ABA applied are important in controlling growth form and not the absolute levels of these hormones. Applications of growth retardants (Chlormequat, Ancymidol, and SADH) stabilize the mature form by preventing spontaneous reversions induced under low light intensity. These two lines of evidence support the hypothesis that the mature morphological form can be stabilized by regulating the effective level of gibberellins in the plant and this can be accomplished by inhibition of gibberellin action or gibberellin biosynthesis.
Effects of Anions on Swelling, Respiration, and Phosphorylation of Isolated Corn Mitochondria
Authors: MILLER J. E. , KOEPPE D. E. , MILLER RAYMOND J.
Published: April 2006

The effects of a series of anions on swelling, respiration, and oxidative phosphorylation of corn mitochondria were studied. Active mitochondrial swelling similar to that found with HPO4−2 was demonstrated in the presence of IO3−, NO2−, MoO4−2, SO4−2, HAsO4−2, acetate, S2O3−2, SeO4−2, CrO4−2, and WoO4−2. In general, those anions which caused active swelling also released respiration and reduced the efficiency of oxidative phosphorylation with exogenous NADH as substrate. The degree of passive swelling in the presence of certain of the monovalent anions was found to approximate the order of the lyotropic series (SCN− > CIO4− > I− > NO3− > CI−).
Partial Reversal by Cytokinin and (2‐Chloroethyl)‐Trimethylammonium Chloride of Near‐Ultraviolet Inhibited Growth and Morphogenesis in Callus Cultures
Authors: FRIDBORG GUNNAR , ERIKSSON TAGE
Published: April 2006

Callus cultures of Haplopappus gracilis, Nicotiana tabacum and Allium cepa var. proliferum were in varying degrees inhibited by blue to near‐UV light obtained from fluorescent tubes. The inhibition was considerably reduced for Haplopappus cultures by 6‐(3‐methyl‐2‐buten‐1‐ylamino)‐purine (2 iP) and (2‐chloro‐ethyl)‐trimethylammonium chloride (CCC) in combination. Even separately these compounds stimulated growth in blue but not in white light. A high concentration of 2 iP reduced the inhibiting effects of near‐UV on tobacco tissue cultures, and a synergism was observed between 2 iP and CCC in respect to shoot formation in blue light. Allium callus was not significantly affected by CCC. It was also observed that the concentration of indol‐3‐acetic acid (IAA) was more important for the growth of tobacco cultures in blue than in white light. It is believed that the light‐inhibition of growth is partly due to a photoinactivation of IAA and that 2 iP and CCC might be active through processes controlling the levels of IAA and other growth hormones.
Effects of SO2 on Photosynthesis and Nitrogen Fixation
Authors: HÄLLGREN JAN‐ERIK , HUSS KERSTIN
Published: April 2006

Responses of photosynthesis and nitrogen fixation to NaHSO3 (10−5−5 × 10−3M) were investigated in the lichen Stereocaulon paschale (L.) Fr. and the blue‐green alga Anabaena cylindrica Lemmermann. The treatments were performed in buffered media with varying pH (5.8–8.1) and light conditions (0–32 W × m−2). The activities of the intact organisms were investigated, under the same environmental conditions, with 14C liquid scintillation and acetylene reduction techniques respectively.

The nitrogen fixation proved to be more susceptible than photosynthesis, in both organisms, and in all cases treatments at pH 5.8 were more inhibitory than at higher pH‐values. Treatment with 5 × 10−4M NaHSO3 at pH 5.8 caused no reduction of photosynthesis in S. paschale, while the inhibition of nitrogen fixation was 97%. For A. cylindrica the corresponding values were 40% and 75% respectively. Short‐time treatments of A. cylindrica showed that the nitrogen fixation was more rapidly affected than photosynthesis. The inhibition of nitrogenase activity and CO2‐fixation was smaller in the dark and increased at higher light intensities. Both processes showed a good capacity for recovery after removal of the NaHSO3 solution. Also the clumping ability of A. cylindrica was disturbed by NaHSO3 treatments.
Soluble and Insoluble Protein Patterns during Induction of Freezing Tolerance in Black Locust Seedlings
Authors: BROWN GREGORY N. , BIXBY JAMES A.
Published: April 2006

Protein metabolism plays a major role in the development of freezing tolerance in plants. Soluble and insoluble protein concentrations were followed during induction of freezing tolerance in black locust (Robinia pseudoacacia L.) stem tissues. Soluble proteins were fractionated using two‐dimensional polyacrylamide gel electrophoresis and examined for the presence of glycoprotein fractions. Soluble protein concentration remained relatively constant during early stages of induction of freezing tolerance but increased significantly during later stages, while insoluble protein concentration remained relatively constant throughout induction. A new soluble protein component appeared during later stages of induction and was identified as a glycoprotein. Some glycoproteins are known to have a high water‐binding capacity, which could play a role in intracellular resistance to ice formation during development of freezing tolerance.
An Abscisic Acid‐like Substance in Dry and Soaked Phaseolus vulgaris Seeds Determined by the Lemna Growth Bioassay
Authors: TILLBERG ELISABETH
Published: April 2006

An acid inhibitor, probably abscisic acid (ABA) in low concentrations was found to be present in bean seeds. The evidence is based on data from paper electrophoresis, chromatography, UV absorption and growth inhibition in the Lemna bioassay, sensitive down to a concentration of 10‐11M ABA or 0.02–0.03 ng/flask.

The inhibitor level as measured by this bioassay decreases considerably with increasing soaking time. Acid ether‐soluble inhibitors could even be detected in the soaking water from the soaked seeds.
Cytokinins: A Rapid Extraction and Purification Method
Authors: HAHN HEINZ
Published: April 2006

A method is described for the isolation, purification and quantitation of free cytokinin bases and ribosides using ethyl acetate at pH 7.7 for the extraction. The extraction is almost complete (97.7%) as determined by using N6‐(Δ2‐isopentenyl)adenine‐8‐14C. The subsequent fast purification by chromatography on a standardized silica gel column in chloroform‐methanol (7:3 v/v) is followed by thin layer chromatography (silica gel 60 F254) in chloroform‐acetic acid (8:2 v/v). The recovery of N6‐(Δ2‐isopentenyl)adenine‐8‐14C after this two step purification was 78–82%. The efficiency of the method was determined by applying this procedure to N6‐(Δ2‐isopentenyl)adenine and N6(Δ2‐isopentenyl)adenosine. Using gas liquid chromatography the recovery for N6‐(Δ2‐isopentenyl)adenosine was determined to be 61% and compared to 43% for N6‐(Δ2‐isopentenyl)adenosine, showing the suitability of the described method for gas liquid chromatography.
Effets d'un Sejour à l'Obscurité sur le Pouvoir Germinatif et sur L'Evolution de l'Appareil Photosynthétique des Spores de Funaria hygrometrica
Authors: CHEVALLIER D.
Published: April 2006

In Funaria spores fine structural changes occur, especially in the plastids, during prolonged incubation in darkness on an inorganic liquid medium, although under these conditions germination cannot take place. If then exposed to illumination, these spores germinate rapidly and synchronously. Chloroplasts formed in darkness have thicker grana, absorb more CO2, have a higher reducing power, and give a more intense paramagnetic resonance signal than chloroplasts formed in light.
Respiration and Vitality of Binucleate and Trinucleate Pollen
Authors: HOEKSTRA FOLKERT A. , BRUINSMA JOHAN
Published: April 2006

The respiration and vitality of ungerminated bi‐ and trinucleate pollen were studied in order to determine the influence of relative humidity and temperature on metabolic activity. The gas exchange, germination capacity and staining with tetrazolium bromide were followed under standardized conditions.

A constant respiration rate occurred under conditions of high relative humidity (97%). Per mg pollen, the trinucleate grains of Compositae and Gramineae respired 2 to 3 times as intense as 6 species of binucleate grains. Per unit of pollen protein the differences were even larger. In contrast to binucleate pollen, the longevity of trinucleate pollen was very short and the ability to germinate was lost twice as fast as the respiration capacity. This limits the use of tetrazolium bromide as an indicator of viability.

At reduced relative humidities respiration was strongly restricted, but the longevity of bi‐ and trinucleate pollen considerably increased.

Pollen of Gramineae, however, was very sensitive to changes in relative humidity; short exposure to low relative humidity decreased both the vitality and the capacity to respire.
Embryoid and Plantlet Formation from Stock Cultures of Nigella Tissues
Authors: BANERJEE S. , GUPTA S.
Published: April 2006

Embryogenesis could be induced within a short period in differentiated roots of Nigella sativa on solid Murashige and Skoog's medium containing casein hydrolysate (500 mg/1) and IAA (0.5 mg/1). Experimental root explants were taken from two different stocks: (i) previously differentiated from leaf callus and now being maintained through subcultures in liquid White's medium and (ii) freshly differentiated from leaf callus on solid Murashige and Skoog's medium + casein hydrolysate (100 mg/1) + IAA (0.5 mg/1). Fifty per cent of the embryoids produced 2n plantlets within 40–60 days.
Effects of Small Water Stresses on Cell Turgor and Intercellular Space
Authors: LEVITT J. , ZAKEN R. BEN
Published: April 2006

A link was sought between small water stresses and the larger metabolic changes that accompany them. A simple infiltration weight method of measuring percentage intercellular space is described and its errors evaluated. It yielded values for leaves (16–35%) similar to those recorded elsewhere by the pycnometer method. The percentage of intercellular space decreased to 0–50% of the value in turgid leaves with a simultaneous loss of turgor only in the sunflower leaves. Turgor remained constant in the orange leaves. Similar results were obtained with the pycnometer method. Measurements revealed that the total or most of the decrease in the volume of sunflower leaves on loss of turgor was due to a decrease in area: the smaller decrease in the volume of orange leaves was entirely due to a decrease in thickness. It is suggested that the sclerophyll nature of the orange leaves is an adaptation to prevent a secondary O2‐deficit stress on exposure to a water stress.