bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Importance of Roots in Regulating the Senescence of Soybean Primary Leaves
Authors: HSIA CHUNG PEI , KAO CHING HUEI 
Published: April 2006

AbstractThe role of roots in regulating primary leaf senescence of 14‐day‐old soybean seedlings was investigated. Compared with intact seedlings, the senescence of primary leaves is accelerated by removal of the root system but delayed if apical bud and the first trifoliate leaf are removed. No difference in senescence was found between intact seedlings and seedlings without roots, apical bud, and first trifoliate leaf. Lateral roots seem to play a predominant role in regulating primary leaf senescence. However, neither root nodules nor primary root play any function in senescence.Results indicate that benzyladenine (BA) at optimal concentration (2 mg/1) completely replaces the roots to prevent the senescence of primary leaves, whereas gibberellic acid (GA) and abscisic acid (ABA) accelerate. The effect of indole‐3‐acetic acid (IAA) to replace roots in preventing senescence depends on the season the young seedlings are grown. Additional, though indirect, information of acropetal transport of ABA is provided.In conclusion, it seems that cytokinins in lateral roots play a predominant role in leaf senescence and the normal supply of root cytokinins is important in leaf metabolism.
Daily Patterns under the Life Cycle of a Maize Crop
Authors: ANDRÉ M. , MASSIMINO D. , DAGUENET A. 
Published: April 2006

AbstractCertain activities were studied daily in a self‐regulating growth chamber in four maize plants (Zea mays L. cv. INRA F7 x F2), which had been raised under completely artificial conditions. The transpiration pattern parallels that for photosynthesis, where a marked change occurs at flowering followed by a decline during cob formation. Respiration reaches a maximum at flowering and thereafter remains relatively stable. Final production figures are comparable with those obtained in field plants, but under artificial conditions the water requirement is halved. The results from this study increase our understanding of whole plant physiology and enable us to establish a closer correlation between plants raised in the laboratory and those in the field.
Varietal Differences in Rubidium Uptake Efficiency of Barley Roots
Authors: PETTERSSON SUNE 
Published: April 2006

AbstractUptake efficiency for Rb+ and SO2−4 was different in eight cultivars of barley, Hordeum vulgare L. Rb+ uptake was studied in more detail in low‐and high‐K+ plants of cv. Salve and cv. Hellas at different Rb+ concentrations in the experimental solutions.The K+/Rb+ selectivity of the roots was strongly dependent on the experimental conditions, but changed similarly in the two cultivars. After six days the fresh weight of the shoots was c. 15% higher in ‘Salve’ than in ‘Hellas’. Root development and the average concentration of K+ in the plants were the same. Influx of Rb+ in the roots was up to 75% faster in ‘Salve’ than in ‘Hellas’. Experiments with short‐term Rb+ influx (10 min) + wash (5 min) indicated that the differences in Rb+ uptake efficiency were due to variations in Rb+ influx at the plasmalemma of the root cells. Efflux of 86Rb+ from 86Rb+‐labelled roots was higher in ‘Salve’ than in ‘Hellas’ during the initial 30 min in inactive solution, indicating that passive permeation (leakage) of Rb+ and probably also of K+ at the plasmalemma of root cells of cv. Salve is faster than that of cv. Hellas. The parallel differences between influxes and effluxes explain the comparatively small difference in net uptake between the two varieties.
Organogenesis and Plantlet Formation from Organ‐ and Seedling‐Derived Calli of Rice (Oryza sativa)
Authors: HENKE R. R. , MANSUR M. A. , CONSTANTIN M. J. 
Published: April 2006

AbstractCallus was induced in different somatic organs of Oryza sativa L. Specific minimum 2,4‐dichlorophenoxyacetic acid (2,4‐D) concentrations in the medium were necessary for the induction of callus from different organs while high levels of 2,4‐D (6–10 mg/l) induced callus formation in each organ tested. The optimum 2,4‐D concentration for callus induction and growth for root‐derived calli was 2 mg/l and for leaf‐derived 6 mg/l. Root and shoot organogenesis were induced in both root‐ and leaf‐derived calli by sub‐culturing to a medium lacking 2,4‐D. Root organogenesis occurred at a higher frequency than shoot organogenesis. Shoot organogenesis rarely occurred in calli without differentiated roots. Increased age of callus cultures almost completely inhibited shoot development. The addition of the cytokinin 6‐γ,γ‐dimethylallyl‐amino purine partially restored the potential for shoot organogenesis. Whole plants were easily recovered from the calli and grown to maturity with some plants exhibiting phenotypic abnormalities.
Caractérisation de la glutamate déshydrogénase chez un halophyte obligatoire: le Suaeda maritima var. macrocarpa
Authors: BOUCAUD J. , BILLARD J. P. 
Published: April 2006

AbstractCharacterization of the glutamate dehydrogenase from an obligate halophyte: Suaeda maritima var. macrocarpaThe glutamate dehydrogenase (GDH), E.C. 1.4.1.3, of the obligate halophyte Suaeda maritima (L.) Dum. var. macrocarpa Moq. has been studied. NaCl increase in the culturing solution (0 to 23 g NaCl/litre) lowers the specific activity but does not affect the kinetic characteristics of the enzyme collected after purification on G‐25 Sephadex gel. In optimal conditions, GDH is activated by the addition of 25 mM NaCl in the incubation medium and inhibited with concentrations over 100 mM. The inhibitory activity of the salt induces both a modification of the affinity of the enzyme for substrate (competitive inhibition for ketoglutarate) and a modification of the catalytic potency (non‐competitive inhibition with NADH and ammonium ion). It is suggested that NaCl has a depressing influence on GDH synthesis. There is a fundamental difference between its short time action (in vitro) versus its continuous effect in the culturing solution.
The Photostability of Different Chlorophyll Forms in Dark Grown Leaves of Wheat
Authors: AXELSSON LENNART 
Published: April 2006

AbstractThe effect of denaturing treatments on the stability against high intensity irradiation (red light, 700 W m−2) was investigated in vivo for various chlorophyll forms in wheat. Three pigment forms were investigated: the 650‐form (protochlorophyllide) present in dark grown leaves; the 684‐form (chlorophyllide) formed within 5 s after photoreduction of the 650‐form; and the 673‐form (chlorophyll), into which the 684‐form has been transformed 25 min after photoreduction of the 650‐form. (The pigment forms are denoted by their absorption maxima in the red region before denaturation.)Two denaturing treatments were used: heat treatment (water of 55°C for 2 min) and freezing and thawing (freezing in liquid nitrogen followed by thawing in water of 25°C). Heat treatment as well as freezing and thawing caused a shift in the absorption peak of the two nonesterified pigment forms. The peak of of the chlorophyllide 684‐form shifted to 673 nm and that of the protochlorophyllide 650‐form to 636 nm. The absorption maximum of the chlorophyll 673‐form was not affected by the above treatments.Heat treatment as well as freezing and thawing had profound effects on the structural organization of the plastid pigments, as shown by a decrease in the photostability. For the 684‐form, heat treatment reduced the photostability by a factor of about 14 (half‐life in strong light changed from 170 s to 12 s). Freezing and thawing also reduced the photostability, although the effect was less pronounced (c. 3–4 times decrease in half‐life). Upon transformation of the chlorophyllide 684‐form into the chlorophyll 673‐form (the Shibata‐shift) the pigments became less sensitive to light, and were no longer “aggregated” by heat treatment. The “aggregating” effect of freezing and thawing was still present after the Shibata shift. The results thus verify a clear difference in structural organization of the 684‐form and the 673‐form, since the two pigment forms were differently affected by heat treatment. The 650‐form behaved similarly to the 684‐form, although it appeared to be slightly less aggregated by heat treatment. — The decrease in photostability, caused by heat treatment of the 684‐form, changed the kinetics for the photodecomposition from a first towards a second order reaction.
Effect of Temperature, Photoperiod and Several Growth Substances on the Cold Hardiness of Chrysanthemum morifolium Rhizomes
Authors: FAYYAZ MOHAMMAD M. , McCOWN BRENT H. , BECK G. E. 
Published: April 2006

AbstractThe effect of 14 combinations of photoperiod, soil and air temperature, and growth substance applications on the cold hardiness of Chrysanthemum morifolium‘Astrid’ rhizomes was evaluated. Both triphenyl tetrazolium chloride and regrowth tests were used to determine the viability of the cold‐stressed rhizome tissues. The rhizomes exhibited different degrees of cold hardiness under these environmental conditions. A combination of short photoperiod and low air and soil temperatures induced maximum cold hardiness. Low soil temperature accompanied by long photoperiods and warm aerial temperatures did not induce rhizome hardening, while some hardening in cool soils was evident under either short photoperiods or low aerial temperatures. Warm soils reduced rhizome hardening under the normally inductive short photoperiod‐cool aerial conditions. Since the induction of rhizome hardening was dependent on the induction of the aerial organs, the involvement of translocatable hardiness promoters is indicated. Foliar applications of low levels of gibberllic acid (GA3) or abscisic acid only slightly influenced rhizome hardiness.
Changes in Gene Expression from Diploid to Autotetraploid Status of Lycopersicon esculentum
Authors: ALBUZIO A. , SPETTOLI P. , CACCO G. 
Published: April 2006

AbstractThe activity levels of enzymes involved in photosynthesis, respiration and nitrogen metabolism were evaluated in a diploid and in the derived autotetraploid Lycopersicon esculentum. The autotetraploid exhibited, compared to the diploid, higher protein and reduced dry matter content; reduced rate of protein synthesis; enhanced activity of malate dehydrogenase, acid invertase, glutamate dehydrogenase, and nitrate reductase; decreased peroxidase activity; unchanged polymorphism of the above‐listed enzymes as revealed by electrofocusing, namely reduced CO2 fixation caused by lower ribulose‐1‐5‐diphosphate carboxylase and even lower phosphoenolpyruvate carboxylase activities in accordance with a smaller contribution of the C4 carboxylating cycle; lower activities of the two “key” enzymes of photorespiration ribulose‐1‐5‐diphosphate oxygenase and glycolate oxydase. The results suggest that the gene expression of the double gene dosage is enhanced in some cases and depressed in others, resulting in more unfavourable balance of the metabolic settlement.
Lipid Composition of the Roots of Plantago Species: Response to Alteration of the Level of Mineral Nutrition and Ecological Significance
Authors: KUIPER DAAN , KUIPER PIETER J. C. 
Published: April 2006

AbstractIn a study of the adaptation of Plantago species to their specific environment the lipid composition of the roots of several species: Plantago major L. ssp. major, Plantago major L. ssp. pleiosperma Pilger, Plantago lanceolata L., Plantago media L., Plantago maritima L., Plantago coronopus L. was studied as well as the effect of the nutritional regime. Upon exposure to low‐salt conditions Plantago major L. ssp. major L. and Plantago maritima L. maintained the level of free sterols in the roots, despite a depressed level of total sterols, and the root lipids were more saturated than under high‐salt conditions. Both factors may reduce nutrient leakage from the roots to the low‐salt condition. Upon exposure to low‐salt conditions, all Plantago species showed a decreased level of galactolipid (exception: Plantago coronopus) and a decreased level of sitosterol (exception: Plantago maritima); the latter being compensated by an elevated level of cholesterol + tocopherol in Plantago major ssp. pleiosperma, Plantago lanceolata and Plantago media. Plantago coronopus was the only species which under low‐salt conditions showed an increased level of free sterols, among which cholesterol was the most important; thus indicating a high degree of regulation of membrane permeability under alternating nutritional conditions. The level of sulfolipid was kept constant in all Plantago species, with the highest level observed in Plantago maritima. The role which various lipids may play in maintenance of membrane integrity under alternating nutritional conditions is discussed.
Concanavalin A Improves the Polyethylene Glycol Method for Fusing Plant Protoplasts
Authors: GLIMELIUS K. , WALLIN A. , ERIKSSON T. 
Published: April 2006

AbstractAn improved method for polyethylene glycol‐induced fusion of protoplasts isolated from auxotrophic mutants of Nicotiana tabacum L. cv. Gatersleben was developed. By using Petri dishes coated with concanavalin A the attachment of protoplasts induced by polyethylene glycol was strengthened. As a consequence of the stronger attachment more fusion products remained after the dilution and washing procedure. It was also found that a shorter treatment combined with a more rapid dilution of the polyethylene glycol solution was superior to previous fusion methods used for plant protoplasts.
On the Question of Stem Polarity with Respect to Auxin Transport
Authors: ZAJACZKOWSKI STEFAN , WODZICKI TOMASZ J. 
Published: April 2006

AbstractThe effect of section length and number of longitudinally contiguous cells upon polar transport of natural auxin from the pine stem cambial region was investigated with oat coleoptile curvature tests. Basipetal and acropetal efflux of auxin to agar declines with increasing length of the sections, but the polarity quotient varies little and is similar to the polarity of individual cells. An integrated system of cells produces a wave along the stem in the efflux of auxin from consecutive segments. The possible role of such waves in development of polarity gradients and of the morphogenic maps of orientation of cells in the stem cambial region is discussed.
Half‐life of tRNA Containing N6(Δ2‐isopentenyl)adenosine in Lactobacillus acidophilus ATCC 4963
Authors: HELBACH MAX , LEINEWEBER MICHAEL , KLÄMBT DIETER 
Published: April 2006

AbstracttRNA containing N6‐(Δ2‐isopentenyl)adenosine may be precursors for the plant hormone cytokinin. To discriminate between tRNA containing and not containing cytokinin nucleotides, double labelling experiments were made by the use of [214C]‐mevalonic acid and [3H‐methyl]‐methionine. At a generation cycle of 2 h for Lactobacillus acidophilus ATCC 4963, the half‐lives of tRNA labelled with [3H‐methyl]‐methionine and [2‐14C]‐mevalonic acid are similar, namely 3 h. Isopentenylation of tRNA could be measured to be maximally 1:10.
Nodule Nitrate Reductase as a Source of Reduced Nitrogen in Soybean, Glycine max
Authors: RANDALL DOUGLAS D. , RUSSELL WALTER J. , JOHNSON DAVID R. 
Published: April 2006

AbstractHydroponically grown soybeans were fed 15N‐enriched NaNO3 at nine reproductive stages of development. The stem exudates contained excess 15N in the fully reduced nitrogen fraction. The soybean nodules had high nitrate reductase activity, whereas the roots had no detectable nitrate reductase activity. Based on these results, we concluded that the nodule nitrate reductase system has the potential of contributing significantly to the nitrogen economy of the plant.
Chlorophyllase in Phaeodactylum tricornutum Photosynthetic Membranes. Extractability, Small‐Scale Purification and Molecular Weight Determination by SDS‐Gel‐Electrophoresis
Authors: TERPSTRA WILLEMKE 
Published: April 2006

AbstractThe extractability of chlorophyllase is used as an indicator for the way in which the enzyme is incorporated in Phaeodactylum tricornutum photosynthetic membranes. Whereas with various aqueous solutions no appreciable amount of chlorophyllase is washed from the membranes even after chloroform‐pretreatment. the enzyme can be extracted with aqueous solutions after practically all the lipids have been removed by means of 80% acetone.The proteins in an aqueous extract of the membranes thus treated were separated by electrophoresis on a 4% polyacrylamide gel; extraction of the active protein from several gels yielded a purified chlorophyllase solution.As with the intramembraneous enzyme, activity of purified, solubilized chlorophyllase depends upon the combined presence of MgCl2 and dithiothreitol. The enzyme is inactivated upon heating at 56°C for 5 min.After SDS‐gel‐electrophoresis of an enriched extract, enzyme activity could be localized in the gels. The molecular weight of SDS‐treated chlorophyllase, or of its principal subunit, was estimated to be about 38 kilodaltons.The results are discussed in terms of the identity of prochlorophyllase.
Modalités du transport et du métabolisme de l'AIA 14C ou AIA 3H en relation avec la morphogenèse des bourgeons axillaires chez le Scrophularia arguta
Authors: MIGINIAC E. , SOSSOUNTZOV L. , DUGUE N. 
Published: April 2006

Abstract Modes of transport and metabolism of
14
C‐IAA and
3
H‐IAA in relation to morphogenesis of axillary buds in Scrophularia arguta.The main objectives of this study were to investigate the morphogenetic role of IAA on the growth and development of axillary buds. After foliar applications of radioactive IAA for 6 h on intact plants of Scrophularia arguta Sol. the characteristics of auxin transport were studied by liquid scintillation counting, thin layer chromatography and microautoradiography. The main part of the radioactivity moved at a mean rate of 7 mm/h. Over long periods of transport, the tracers accumulated at the base of the axis and in the roots. The nodes were a little richer in 3H or 14C than the internodes. This fact seemed to be correlated with the vascular organization of this part of the stem. A very weak proportion of tracers was found in axillary buds. The radioactivity was to about 50% associated with the IAA molecule; the rest corresponded essentially to indolyl‐4‐acetyl‐l‐aspartic acid and indolyl‐3‐aldehyde. Tracers were mainly concentrated in the phloem along the whole axis and, to a lesser extent in some of the young differentiating metaxylem vessels, and in the medullary rays. No radioactivity was found in the cambial zone and in the mature xylem, nor in the parenchymas. These results support the view of an indirect role of IAA on the axillary bud growth and morphogenesis.
The Effect of Gibberellic Acid and Guanosine Monophosphates on Extension Growth, Leaf Production and Flowering of Impatiens balsamina
Authors: SHARMA REETA , KUMAR SURINDER , NANDA K. K. 
Published: April 2006

AbstractGibberellic acid (GA3) increases the height of Impatiens balsamina under both 8‐ and 24‐h photoperiods. The height also increases with all guanosine monophosphates (GMPs) under 8‐h photoperiods but only with 5′‐GMP under 24‐h photoperiods. GA3 as well as GMPs increase the number of leaves under 8‐h but not under 24‐h photoperiods. GA3 as well as GMPs induce floral buds under strictly non‐inductive photoperiods and increase the number of floral buds under 8‐h photoperiods. The floral bud initiation occurs earlier when cGMP is used in combination with 100 mg/l GA3.
Isoperoxidases in Epidermal Layers of Tobacco and Changes during Organ Formation in vitro
Authors: THORPE TREVOR A. , THANH VAN MARIE TRAN , GASPAR THOMAS 
Published: April 2006

AbstractThe content and pattern of soluble isoperoxidases were determined in epidermal explants taken from different internodes of tobacco plants in the vegetative and floral states. There were qualitative and quantitative differences in the isoperoxidases, with a decrease in content and fewer bands being observed acropetally, i.e., in going from the base of the stem towards the apex. Epidermal explants from floral branches were grown in in vitro culture, with various media moditications, to form de novo floral or vegetative buds, roots or callus. Changes in soluble isoperoxidases were followed electrophoretically in relation to these varying morphogenetic pathways. In each of them, the number of bands increased on both the anodic and cathodic sides with time in culture. Compared to each other these four morphogenetic programmes were different in their peroxidase zymograms, mainly through varying kinetics in the development of activity of the isoenzymes. The changes observed during root and vegetative bud formation agree with previously published data, and the changes during floral bud formation agree with those observed in vivo.
Rapid Bioassay for Auxin
Authors: MEUDT WERNER J. , BENNETT HOWARD W. 
Published: April 2006

AbstractA rapid bioassay is described for the detection of growth substances. The bioassay is simple to perform under ordinary laboratory or classroom conditions and the sensitivity to auxin is comparable to other bioassays, including those using Avena first internode sections. The bioassay is performed on isolated first internode sections from partly etiolated bean plants (Phaseolus vulgaris L. cv. Bush Burpee Stringless Bush Bean). The test material is applied to one side and near the base of the section. Auxin treatments induce curvature and the distance of the lateral displacement of the apical portion of the segment is proportional to the concentration applied. Routinely, the indole 3‐acetic acid response is measured 1 to 3 h after treatment. The sections also respond to gibberellic acid (GA3), which induces an increase in overall length, but unlike auxin, GA3 does not cause curvature. The test compounds are applied via a small filter paper disk that provides a convenient means for studying interactions of two or more compounds by co‐applications. Auxin‐induced growth can be monitored with a sensitive motion detector. Data are presented which confirm the usefulness of the assay.
Inhibition of Photosystem II in the Green Alga Ankistrodesmus falcatus by Copper
Authors: SHIOI YUZO , TAMAI HIROKO , SASA TSUTOMU 
Published: April 2006

AbstractCopper strongly inhibited 2,6‐dichloroindophenol (DCIP) photoreduction in the broken cells of the green alga Ankistrodesmus falcatus (C303), and the activity lost could not be restored by adding 1,5‐diphenylearbazide (DPC). Inactivation of the DCIP Hill reaction reached 45% after incubation with 10 μM cupric sulfate for 20 min. In the same time, copper (13 μg/mg chlorophyll) was bound to the broken cells. Addition of 10 mM KCl reduced copper binding by about 53%. Fluorescence intensity at room temperature decreased upon addition of cupric sulfate and was partially restored by adding 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), These results suggest that copper inactivates electron transport between the oxidizing side of the reaction center of photosystem II and the electron‐donating site of DPC. Further, the effect of light intensity shows that copper mostly affected the reaction rate of the dark step and had less inhibitory effect on the quantum efficiency of the primary reaction of electron transport in photosystem II.