bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photophysiology of Kalanchoë Seed Germination
Authors: FREDERICQ H. , ELDABH R. , GREEF J. DE , MATON J. 
Published: April 2006

AbstractThe effects of irradiations with different proportions of red/farred light and of gibberellic acid on the phytochrome‐mediated seed germination of Kalanchoë blossfeldiana cv. Feuerblüte, were studied.The seed coat transmits much more red than far‐red light, and therefore the energy ratio between 660 nm and 730 nm is given only for the transmitted light. Decreasing this ratio from 65 to 1.0 caused only a very slight inhibition. If this ratio is further lowered to 0.64, a 10 min terminal irradiation after a 3‐h white light photoperiod is inhibitory, but a 12‐h photoperiod or continuous irradiation is not. If the ratio is decreased to 0.44 or 0.31, a 12‐h photoperiod is now also inhibitory, although continuous irradiation and 10 min terminal irradiation are still more inhibitory. These results are discussed in terms of phytochrome phototransformations.Although gibberellic acid is unable to cause any germination in complete darkness, it can result in a very high germination percentage, if combined with treatments which by themselves do not induce any germination such as continuous far‐red, terminal far‐red after short photoperiods, or very short photoperiods at 25°C. These results point to a strong synergism between gibberellic acid and the so‐called stabilized form of phytochrome, P*FR.
Characterization of Plant Alcohol Dehydrogenase
Authors: LEBLOVÁ SYLVA , MANČAL PETR 
Published: April 2006

AbstractThe final activity of the alcohol dehydrogenase (E.C.1.1.1.1, abbreviated ADH) from germinating pea, isolated by fractionating with ammonium sulphate, chromatography on DEAE cellulose and gel filtration, was 80,000, from bean 25,000 and from lentil 13,500 units per mg protein. Molecular weights of the ADHs are close to each other: pea and bean ADH 60,000, lentil ADH 70,000. The Km values are mutually similar with three enzymes, i.e. of the order of 10−4M for NAD and 10−2M for ethanol. The pH optima lie in the alkaline region. These enzymes catalyse oxidation of a number of monovalent alcohols. At temperatures above 60°C the enzymes are thermally unstable. Stability is enhanced slowly by ethanol but not by NAD. Pyrazol, imidazol and pyridine inhibit plant ADH similarly to the enzyme from horse liver. There is a similarity between plant alcohol dehydrogenases and animal and yeast enzymes.
The Initiation and Maintenance of Vicia faba Tissue Cultures
Authors: MITCHELL J. P. , GILDOW F. E. 
Published: April 2006

AbstractExplants obtained by removing the radicle tip and the plumule from embryos of Vicia faba have been induced to form callus in culture. Of a range of agar‐solidified culture media tested, only that of Schenk and Hildebrandt (1972) was consistently successful. Improved growth, measured as increasing fresh weight was obtained by increasing the nitrogen content of the medium, either as potassium nitrate or as ammonium nitrate. A kinetin concentration of 0.01 mg/1 (5 × 10−8M) and a 2,4‐dichlorophenoxyacetic acid (2,4‐D) concentration of 0.5 mg/1 (2.3 × 10−6M) allowed optimum initial callus growth. A 2,4‐D concentration of 2.3 × 10−8M, while insufficient to induce callus formation was able to inhibit lateral root development which occurred from embryo explants cultured without added 2,4‐D. Subcultured tissue grew well on media supplemented with casein hydrolysate or a mixture of the eight most common amino acids in casein hydrolysate. Growth in subcultures was inhibited by two other amino acid mixtures used by other workers for different species.
Translocation and Complex Formation of Root‐applied 2,4‐D and Picloram in Susceptible and Tolerant Species
Authors: HALLMÉN ULF 
Published: April 2006

AbstractTranslocation and complex formation of 14C‐labelled 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) in seedlings of sunflower (Helianthus annuus L. var. uniflorus), rape (Brassica napus L. cv. Nilla), wheat (Triticum aestivum L. cv. Starke), and Norway spruce (Picea abies (L.) H. Karst.) were studied. The herbicides were absorbed through the roots from the nutrient solution, Picloram was well translocated to the shoots of the four species; while the acropetal translocation of 2,4‐D was small except in rape.In 2,4‐D‐susceptible sunflower and rape and in picloramsusceptible sunflower and spruce the herbicides were recovered mainly in the uncomplexed form. In 2,4‐D tolerant wheat and spruce most of the absorbed 2,4‐D was converted into water‐soluble or TCA‐insoluble complexes. In picloram‐tolerant wheat and in relatively picloram‐tolerant rape, the absorbed picloram was also converted into complexes recovered predominantly in the water‐soluble fraction. Most of the complexes released free herbicides by hydrolyzing in NaOH or HCI. The results further support the hypothesis that complex formation counteracts herbicide toxicity.
Ion Uptake Efficiency of Sunflower Roots
Authors: PETTERSSON SUNE 
Published: April 2006

AbstractThe term ion uptake efficiency is used for the rate of uptake of a particular ion from nutrient solutions holding a standard concentration of that ion (0.5 mM sulphate, 1.5 mM phosphate or 2.0 mM rubidium). The uptake efficiency for rubidium and phosphate in roots of intact sunflower plants depended on the salt status of the plants and on the concentration of the ion under investigation in pretreatment solutions. The effect of pretreatment was a rapid process causing differences of more than 300% in ion uptake efficiency within 1 h, depending on the composition of the pretreatment solution. At concentrations above 0.1 mM the rate of uptake of rubidium in the root was higher than the net potassium uptake necessary for adequate growth. The rate of sulphate uptake was related to potassium uptake but not to phosphate uptake. It is suggested that ion uptake of the roots is regulated by internal factors as well as by direct interactions between the medium and the absorbing surfaces.
Natural Chlorinated Auxins Labelled with Radioactive Chloride in Immature Seeds
Authors: ENGVILD K. C. 
Published: April 2006

AbstractImmature seeds were harvested from 15 species grown in perlite/vermiculite containing 36Cl‐, but with very low levels of cold Cl‐. Autoradiograms of one‐ and two‐dimensional thin layer chromatograms of butanol extracts of lyophilized seeds indicated several radioactive compounds besides the 36Cl‐ in many species. In pea the radioactivity cochromatographed with 4‐(or 6‐)chloroindolyl‐3‐acetic acid and its methyl ester; in other species radioactivity was found near these chlorinated indolyl‐acetic acid markers.
Salt‐stimulated Phosphoenolpyruvate Carboxylase in Cakile maritima
Authors: BEER S. , SHOMER‐ILAN ADIVA , WAISEL Y. 
Published: April 2006

AbstractThe effects of NaCl and other salts, in vivo and in vitro, on the activity of phosphoenolpyruvate carboxylase from the coastal C3 halophyte Cakile maritima Scop, were investigated.Plants grown with 100 mM NaCl in their growth medium yielded some 30% higher rates of phosphoenolpyruvate carboxylase activity than did salt‐depleted plants.Activity of the enzyme was stimulated when NaCl was added to the reaction mixture in concentrations of up to 200 mM. The magnitude of this in vitro stimulation was similar for plants grown in the presence or absence of NaCl. The effect seems to be caused by chloride rather than by sodium ions.
Relative Contribution of Ribulose 1,5‐Diphosphate Carboxylase and Phosphoenolpyruvate Carboxylase to CO2 Fixation Activity in Roots of Dark‐grown or Light‐grown Lens culinaris Seedlings
Authors: NATO A. , DELEENS E. 
Published: April 2006

AbstractThe pathway of carbon assimilation in greening roots was compared to the pathway in leaves of Lens culinaris seedlings by means of labelling distribution analysis among the products of 14CO2 fixation in vivo, and in vitro with ribulose 1,5‐diphosphate as the substrate. In green leaves, CO2 fixation via ribulose 1,5‐diphosphate carboxylase predominated largely while, in green roots, this carboxylase activity and the phosphoenolpyruvate carboxylase contributed almost equally to the whole in vivo CO2 fixation. A participation of the activities of both carboxylases according to the double carboxylation pathway in the synthesis of dicarboxylic acids (malate and aspartate) was demonstrated in vitro after 48 h of greening in roots but seemed to be absent in in vivo experiments.
Uptake of Zinc and Strontium by Brown Algae
Authors: SKIPNES OLAV , ROALD TONE , HAUG ARNE 
Published: April 2006

AbstractThe accumulation of radioactively labelled strontium and zinc by living and killed tips of the brown alga Ascophyllum nodosum (L.) Le Jol. was studied and compared with the uptake in some model substances.The accumulation of strontium was reversible, and similar in living and killed plants. Equilibrium was established within a couple of days. Strontium accumulation seemed to be an ionexchange process involving the negatively charged intercellular polysaccharides, probably mainly alginate.Only a small fraction of the zinc uptake in living algae seemed to be due to a similar ion exchange with the intercellular polysaccharides. The characteristic features of the zinc uptake was a constant, slow, irreversible accumulation persisting for very long periods of time. In dead algae the uptake was rapid and reversible, indicating that the algae contained zinc‐binding substances which were not directly accessible to the zinc ions in the surrounding seawater before killing.It is proposed that these substances in the living plant are contained in membrane‐surrounded structures, probably vacuoles. These membranes, effectively regulating the zinc uptake in the living cells, are destroyed by killing, making the zinc binding substances directly accessible.The transfer of zinc from the reversible intercellular sites to the irreversible cellular sites continued undisturbed during low‐tide periods. The intercellular charged polysaccharides thus function as ion buffers, allowing ion uptake into the cell at a constant rate, independent of the tidal movements.
Inhibition of Corn and Sunflower Photosynthesis by Lead
Authors: BAZZAZ F. A. , CARLSON ROGER W. , ROLFE G. L. 
Published: April 2006

AbstractDetached corn and sunflower leaves supplied with PbCl2 via the transpiration stream exhibited reduced rates of photosynthesis. The difference between species in the amount of Pb taken up was in direct proportion to their respective transpiration rates. For both species the reduction in photosynthesis and the amount of Pb taken up increased with increasing treatment concentrations. A corresponding reduction occurred in the rate of transpiration suggesting that stomatal resistance may be increased by Pb contamination. The pathways of CO2 and water vapor exchange are discussed in relation to the effects of Pb on photosynthesis and transpiration.
Light‐stimulated Absorption of Nitrate by Wolffia arrhiza
Authors: SWADER J. A. , STOCKING C. R. , LIN CHIN HO 
Published: April 2006

AbstractThe mechanism of the light‐stimulated absorption of nitrate by Wolffia arrhiza was studied. The nitrate‐absorption mechanism in ammonium‐grown plants is stimulated by the presence of nitrate. In a manner similar to the absorption of many other ions, the absorption of nitrate follows a typical biphasic pattern in relation to external nitrate concentration. Mechanism 1 is effective at nitrate concentrations up to 0.5 to 0.75 mM and mechanism 2 becomes operative at higher nitrate levels.Light stimulates the absorption of nitrate independently of the effect of light on the reduction of nitrate. The effects of uncouplers, inhibitors, and light of wavelengths of 700 nm or longer indicate that nitrate absorption by Wolffia cells is reduced when non‐cyclic electron transport is blocked. It is postulated that under this condition, ATP in the chloroplast (produced by cyclic photophosphorylation) may be less readily transported across the chloroplast envelope than when non‐cyclic electron transport is proceeding.
Germination of Seeds in the Shadow of Plants
Authors: GÓRSKI TADEUSZ 
Published: April 2006

AbstractAn attempt to prove the ecological significance of red‐far red control mechanisms in seed germination was made. The seeds of 30 species were exposed beneath the plant canopies. All the normally light‐stimulated seeds, and also seeds of 14 (out of 19) “insensitive’ species and seeds of 1 (out of 4) light‐inhibited species, were inhibited or significantly retarded in their germination, as compared with seeds exposed to diffuse light in an artificial construction.Further experiments with “insensitive’ seeds of Lactuca sativa L. cv. Cud Vorburgu showed that after prolonged plant‐shadow treatment the seeds became light‐sensitive in the usual phytochrome‐mediated manner. Seeds exposed under the plant canopies during a few days were extremely sensitive to red or white light, but this sensitivity diminished slowly in the course of treatment.The spectral composition of light filtered through the leaves shows great preponderance of far red radiation. The red‐far red reversion can be simply obtained with the natural light and a leaf. In open stands bright weather retards considerably the germination of lettuce, cloudy weather brings about full germination.Some considerations on the ecological significance of seed behaviour, particularly as connected with plant competition, are given.
Changes in Sapwood of Roots of Norway Spruce, Attacked by Fomes annosus
Authors: POPOFF THOMAS , THEANDER OLOF , JOHANSSON MARTIN 
Published: April 2006

AbstractAcetone extracts of sapwood and reaction zone of spruce roots attacked by Fomes annosus, collected in February, June and October, were separated into resinous and phenolic fractions. The fractions were further separated by column, thin layer and gas liquid chromatography, followed by biological tests, using Fomes annosus and other rot fungi. The reaction zone contained quantitatively less light petroleum soluble compounds than the sapwood but more acids. The phenolic content was about ten times higher in the reaction zone than in the sapwood. Nine lignans and one simple phenol (4‐methylcatechol) were identified and quantitatively estimated in the reaction zone. The resinous fraction of the extract from the reaction zone as well as some of the lignans and 4‐methylcatechol inhibited fungal growth, in some cases followed by detoxification and continued growth. The predominant lignan, hydroxymatairesinol, had no effect on Fomes annosus or five other wood degrading fungi. About 15 unidentified phenols were observed, some of them probably of importance as inhibitors, either alone or in combination with other phenols.
Control of Bean Bud ATP Levels by Regulatory Molecules and Phytochrome
Authors: KIRSHNER RONALD L. , WHITE JUDITH M. , PIKE CARL S. 
Published: April 2006

AbstractThis study assessed the involvement of exogenously supplied acetylcholine, dibutyryl cyclic AMP, and various inhibitors of acetylcholine and cyclic AMP metabolism on the rapid phytochrome‐mediated alteration in the ATP content of etiolated bean buds (Phaseolus vulgaris L. cv. Red Kidney). ATP was extracted in boiling water and measured by the firefly luciferin‐luciferase assay. The depression of ATP content by low levels of either acetylcholine or dibutyryl cyclic AMP was independent of irradiation. Atropine, AMO‐1618, and theophylline all altered ATP content, and the effects differed in red light and in darkness. In contrast to other reports, no straightforward model of phytochrome action through either acetylcholine or cyclic AMP could be constructed. Also, the time course of ATP content during the standard 5 min red‐irradiation period was determined, and effects of light are observed within 1 min.
In vitroPost‐germination Growth and Development of Embryos ofAlectra(Scrophulariaceae)
Authors: OKONKWO S. N. C. 
Published: April 2006

AbstractIn vivo, seeds of the obligate root parasiteAlectra vogeliiBenth. (Scrophulariaceae) germinate only after being soaked in water for a period of time (pretreatment) followed by stimulation by certain factors exuded from a host root. Germinated seedlings do not develop beyond radicle emergence, and finally die, unless their radicles make contact with and penetrate into a host root conductive system.In vitro, germinated embryos obtained by exposing sterilized and pretreated seeds to root exudate ofVigna unguiculatawere aseptically cultured on Knop's, White's and Murashige and Skoog's media. The embryos grew into seedlings with shoots and roots on a medium containing mineral salts and sucrose, but not on mineral salts alone. Seedling performance was generally not improved when the mineral salts‐sucrose media were supplemented with vitamins. Shoot extension growth was better on Murashige and Skoog's mineral salts‐sucrose medium than on Knop's or White's medium. However, seedling development was greatly boosted when cultivated on White's minerals salts‐sucrose medium supplemented with coconut milk. Seedlings turned green on transfer to light but did not flower. The successful culture of these embryos and seedlings on a simple, chemically defined medium of mineral salts and sugar suggests that these nutrient components are the minimal external requirements for stimulation and support of normal seedling growth. These may be obtainedin vivoby the parasite's tapping of the host root conductive system.
The Effect of Dichlorophenyldimethylurea on Light‐Stimulated 22Na+, 42K+ and 86Rb+ Absorption in Different Tissues of Phaseolus vulgaris Leaves
Authors: JACOBY BENJAMIN 
Published: April 2006

AbstractThe light‐stimulated absorption of 86Rb+ by Phaseolus vulgaris L. leaf slices was found to be sensitive to dichlorophenyldimethylurea in air as well as in nitrogen, whereas light‐stimulated 22Na+ absorption in nitrogen was not sensitive to this inhibitor. The absorption of 22Na+ is not affected by light in air. The absorption of 42K+ is enhanced by a dichlorophenyldimethylurea‐insensitive light effect under anaerobic conditions and further increased by light in the absence of the inhibitor. Light‐enhanced 42K+ absorption in air was also inhibited by dichlorophenyldimethylurea. Previous work showed that light‐stimulated 86Rb+ and 42K+ absorption by Phaseolus vulgaris leaf slices is restricted to the guard cells. The present results are discussed with reference to the effect of light on stomatal opening.
Quantacorrected Spectrometer for Recording Different Types of Photobiological, Photochemical, and Spectrophotometric Measurements
Authors: HALLDAL PER , NORDSTRÖM BERTIL , ÖQUIST GUNNAR 
Published: April 2006

AbstractAn instrument is described which functions as a spectrophotometer, In addition it measures action spectra of photobiological processes, excitation and emission spectra of fluorescence, and gives data for calculation of action spectra of partial reactions of photosynthesis and photocontrolled enzymatic reactions. The instrument has a Bausch and Lomb 250 mm grating monochromator. Equal numbers of quanta at different wavelengths are adjusted electronically with control of the slit through a quantacorrected photocell and a servo motor which is programmed by a cam connected to the wavelength drive.
Abscisic Acid as Inhibitor of α‐Amylase from Aspergillus and Bacillus subtilis
Authors: HEMBERG TORSTEN 
Published: April 2006

AbstractAbscisic acid (ABA) inhibited the activity of α‐amylase from both Aspergillus and Bacillus subtilis in vitro if ABA and enzyme solutions were allowed to react with each other before adding to the starch solution. If the ABA solution was put to starch before adding the enzyme, no inhibition occurred.The inhibition increased with increasing time between mixing ABA and enzyme solutions and adding the mixture to starch. It was not the absolute amounts of enzyme and ABA which were of importance for the inhibition, but the concentrations of ABA and enzyme in the ABA + enzyme mixture. Within certain limits the inhibition was proportional to the concentration of ABA, so that it should be possible to use the inhibition in quantitative tests for inhibitors.Dialysis of a mixture of ABA and enzyme showed that ABA is bound to the enzyme. The enzyme was still inhibited after dialysis for 25 h. On the other hand, partitioning with diethylether from acid water solution could free the enzyme from all ABA. Supposedly ABA acts as an allosteric inhibitor.The results may offer the foundation for one possible way to explain why inhibitors in plants sometimes inhibit growth and sometimes do not. If inhibitor, enzyme and substrate are compartmentalized, the degree of reaction should depend upon the sequence in which the three components meet each other.
Radial Oxygen Loss from Roots: The Theoretical Basis for the Manipulation of Flux Data Obtained by the Cylindrical Platinum Electrode Technique
Authors: ARMSTRONG W. , WRIGHT E. J. 
Published: April 2006

AbstractA résumé is given of the cylindrical platinum electrode technique for measuring the rate of oxygen release from the submerged roots of intact plants.Methods are then described for manipulating the oxygen flux data to quantify the following root characteristics: total effective internal diffusional resistance, non‐metabolic (pore‐space) resistance, internal apical oxygen concentration, effective diffusion coefficient of internal transport and fractional porosity, and the respiratory contribution to internal transport. The diffusional resistance of the root wall is discussed and the method formerly suggested for converting low temperature flux data to the appropriate room temperature values (Armstrong 1971) is revised. Finally, suggestions are made for overcoming the difficulties encountered in using flux data for comparative work if the roots differ in their apical radii.
Evolution des Teneurs en Acides Chlorogénique et “Isochlorogénique’ au Cours du Traitement de Vernalisation des Racines de Cichorium intybus
Authors: PAULET F. MIALOUNDAMA et P. 
Published: April 2006

AbstractIn a cold‐requiring variety of endive (chicory, Cichorium intybus L. ev. Witloof) we could demonstrate a relationship between the variations in the content of chlorogenic acid during the cold treatment of the roots and their disposition to produce flowers in vitro. An increase in the level of chlorogenic acid in the roots preceded the development of their aptitude to form flower buds. In addition, the three main forms of “isochlorogenic’ acid are present in the roots of this cultivar: 3,5‐dicaffeoyl‐quinic acid, 3,4‐dicaffeoyl‐quinic acid, and traces of 4,5‐dicaffeoyl‐quinic acid. The variations in the levels of chlorogenic and “isochlorogenic’ acids indicate that part of the chlorogenic acid (3‐caffeoyl‐quinic acid) is converted to 3,5‐dicaffeoyl‐quinic acid.