bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic Resistance of Rough Lemon Roots
Authors: RAMOS CARLOS , KAUFMANN MERRILL R. 
Published: April 2006

AbstractA pressure chamber technique was used to estimate hydraulic root resistance in rough lemon (Citrus jambhiri Lush.) seedlings. The effect of previous water stress on hydraulic root resistance was evaluated. A factorial 3 × 3 design with four replications was established with potted rough lemon seedlings in a growth chamber. Three water‐stress treatments were applied by watering at intervals of 1, 2 and 3 days, and root resistance measurements were made after 6, 12 and 18 days of treatment. Plants that had experienced mild and severe water stress (irrigation interval of 2 and 3 days, respectively) had higher hydraulic root resistances after several drying cycles than those plants irrigated daily. Additional cycles had no significant effect. The increase in root resistance was not due to decreased root growth but apparently to changes in the permeability of the root cell membranes or to increased suberin deposition in the cell walls of the cortical cells. In a short‐term experiment (1 h), temperature strongly affected water flow through rough lemon roots in the range 5 to 35°C. Temperature influenced root membrane permeability, since reduced blow could not be explained by changes in water viscosity.
Activities of Enzymes Relating to Starch Synthesis and Endogenous Levels of Growth Regulators in Potato Stolon Tips During Tuberization
Authors: OBATA‐SASAMOTO HAMAKO , SUZUKI HIROSHI 
Published: April 2006

AbstractChanges in contents of starch and protein, and activities of enzymes involved in starch synthesis were studied during tubcrization of stolon tips of Solanum tuberosum L. cv. Irish Cobbler. Starch content and activities of phosphorylase and granule‐bound starch synthctase based on fresh weight increased rapidly in the early phase (stage I, the stolon tips just before swelling; stage 2, the swelling tips; stage 3, young tubers of 0.2–0.5 cm diameter), and they all remained nearly unchanged in the later phase (stage 3 to stage 6, young tubers of 3.5 cm diameter). The content of soluble protein based on fresh weight remained unchanged. Activities of soluble starch snythetase and ADP‐glucose pyrophosphorylase were not detected at stage 1 and 2, but increased at later stages.Endogenous levels of auxin, cytokinin and gibberellin were assayed for the materials at the corresponding developmental stages. Auxin content was high at stages 1 and 2, and lowered at later stages. Cytokinin content increased abruptly at stage 6. Gibberellin content was low at all stages.The internal conditions for starch deposition and tuberization in potato were discussed in regard to regulation of enzyme activities by growth regulators.
Uptake of Nitrate by Mutants of Arabidopsis thaliana, Disturbed in Uptake or Reduction of Nitrate
Authors: DODDEMA HENK , TELKAMP G. P. 
Published: April 2006

AbstractThe uptake of nitrate by wildtype plants and chlorate‐resistant mutants of Arabidopsis thaliana (L.) Heynh. was studied by intermittent or continuous measurement of the nitrate concentration of the ambient solution. The uptake rate in the wildtype and the nitrate reductase‐less mutant B 25 showed a dual‐phase relation ship with concentration. Each phase showed Michaelis‐Menten kinetics although multiphasic patterns within each phase could not be excluded. A dual‐phase relationship was also found in the uptake mutant B I. Here, however, phase II did not follow Michaelis‐Menten kinetics and uptake rate of nitrate in the phase II concentration range was considerably lower in the B 1 mutant than in the wildtype. It is concluded that the mutation in B I has disturbed phase II of the nitrate uptake, without affecting phase I, which leads to the suggestion that uptake of nitrate in Arabidopsis is mediated by at least two independent uptake mechanisms.The nitrate uptake rate showed an optimum at pH 8, and it was not stimulated by the presence of calcium. Ammonium had different effects on nitrate uptake: a direct effect, when it was present during the uptake of nitrate, resulting in a release of nitrate and a reduced rate of uptake, and an indirect inhibitory effect, possibly caused by assimilation products of ammonium, which is most pronounced after growth on ammonium as the sole nitrogen source or in long‐lasting uptake experiments in the presence of ammonium. Chlorate also showed a multiple effect, an inhibiting one which proved to be competitive and, at very low concentrations of chlorate, a stimulating one. Evidence was obtained that chlorate and nitrate arc taken up by the same carrier.
Isolation of Mesophyll Protoplasts of Nicotiana rustica and Their Regeneration into Plants Flowering in vitro
Authors: GILL RAVINDER , RASHID A. , MAHESHWARI S. C. 
Published: April 2006

AbstractProtoplasts were isolated from leaves of in vitro grown plants of Nicotiana rustica L. by the one step enzymatic method. With 3% cetlulase in 0.5 M mannitol at 25°C and pH 4.6, within 10–12 h about half the total cells were transformed into protoplasts. The enzyme activity had two pH maxima, one at pH 3.5 and the other at pH 6.5, indicating the presence of isoenzymes. A time‐course study at different temperatures indicated that ai 30°C the protoplasts’ liberation was quicker but it resulted in their subsequent bursting. The protoplasts were cultured in liquid as well as on agar‐jelled medium of Ohyama and Nitsch (1972) supplemented with 2.4‐D and benzylaminopurine, each at I mg/1. and 14% sucrose. Regular divisions could be seen only on agar‐jelted medium. Colonies on transfer to Murashige and Skoog (1962) medium, containing IAA and kinetin, differentiated into plantlets. These plants, within 2 months, flowered in vitro and set seed of which about 20% germinated.
The Effect of Photosynthetic Enhancement on Photorespiration in Sinapis alba
Authors: NILSEN STEIN , HAUGSTAD MAY , HOLMEN AASE T. 
Published: April 2006

AbstractIn Sinapis alba, the Emerson enhancement effect, measured as CO2 uptake, was significantly lower in an O2‐free atmosphere than in normal air. Photorespiration, when measured as 14CO2 release after a period of 14C‐photosynthetic labeling in white or monochromatic light, was reduced during photosynthetic enhancement. The 14C‐glycolate pool and the 14C‐labeled amino acids associated with the glycolale pathway (glutamate, glycine and serine) decreased during photosynthetic enhancement when Pholosyslem I was ‘overexcited’. This demonstrates that photosynthesis and photorespiration are oxygen dependent and that photorespiration is wavelength dependent in Sinapis alba. The effect of oxygen on pholosynthetic enhancement and photorespiraion, as well as the effect of wavelength on these processes suggest that light is involved not only in the production of glycolate, but also in its further metabolism. It seems that Photosystem I is a key factor in the regulation of glycolate metabolism. Furthermore, the product from the consumption of glycolate in a reaction associated with Pholosystem 1 does not seem to be metabolized via the glycolate pathway.
Influence of Aryl Esters of Indole‐3‐acetic and Indole‐3‐butyric Acids on Adventitious Root Primordium Initiation and Development
Authors: HAISSIG BRUCE E. 
Published: April 2006

AbstractSynthetic aryl esters of indole‐3‐acetic acid (IAA) and indole‐3‐butyric acid (IBA) greatly enhanced adventitious root primordium initiation in bean (Phaseolus vulgaris L. cv. Top Crop) and jack pine (Pinus banksiana Lamb.) cuttings, respectively. Bean cuttings produced 95 to 154% more macroscopically visible root primordia in 2 days when treated with phenyl indole‐3‐acetate (P‐IAA), in comparison with an equal concentration of IAA. Substantial but lesser increases occurred when treatment was done with 3‐hydroxyphenyl indole‐3‐acetate (3HP‐IAA). On a molar basis, either P‐IAA or 3HP‐IAA were 10 or more times as efficient as IAA in inducing adventitious root primordium initiation in bean cuttings. Methyl indole‐3‐acetate was no more effective than IAA in these tests.Phenyl indole‐3‐butyrate (P‐IBA) consistently enhanced the number of rooted jack pine seedling cuttings by 11 to 12% in comparison with a 27% higher concentration of IBA.The number of elongated roots (2 mm or more) after 5 days was 165 to 276% greater for P‐IAA than for IAA‐treated bean cuttings. Similar but lesser increases occurred as a result of 3HP‐IAA treatment. P‐IBA in comparison with IBA treatment did not influence either the number of roots or length of the longest root per rooted jack pine cutting.Enzymes in bean and jack pine cuttings hydrolyzed the aryl esters. However, check experiments showed that initial integrity of the esters was required for enhanced activity in inducing root primordium initiation. Treatment of bean cuttings with hydrolysates of P‐IAA, or with IAA and phenol, alone or combined, did not influence root primordium initiation or development in a manner different from treatment with IAA alone.
Importance of Time Constants in an Open Flow System: Mathematical Correction of Fast Ethylene Kinetics in Physiological Studies
Authors: DE GREEF J. A. , VEROUSTRAETE F. , VAN WIEMEERSCH L. , FREDERICQ H. 
Published: April 2006

AbstractA mathematical analysis for fast changes of ethylene concentration in an open flow system (non‐steady‐state conditions) is presented and experimentally tested. In this way it becomes possible to determine true values of ethylene production in the minute range following physiological and environmental changes which influence ethylene evolution. By this procedure ethylene kinetics can also be compared in absolute values independent of flow rate and plant chamber volume.
Time‐course of Nitrate Uptake and Nitrate Reductase Activity in Nitrogen‐depleted Dwarf Bean
Authors: BRETELER HANS , HÄNISCH TEN CATE CHARLOTTE H. , NISSEN PER 
Published: April 2006

AbstractThe rate of nitrate uptake by N‐depleted French dwarf bean (Phaseolus vulgaris L. cv. Witte Krombek) increased steadily during the first 6 h after addition of NO3 ‐After this initial phase the rale remained constant for many hours. Detached root systems showed the same time‐course of uptake as roots of intact plants. In vivo nitrate reductase activity (NRA) was assayed with or without exogenous NO3‐ in the incubation medium and the result ing activities were denoted potential and actual level, respectively. In roots the difference between actual and potential NRA disappeared within 15 min after addition of nitrate, and NRA increased for about 15 h. Both potential and actual NRA were initially very low. In leaves, however, potential NRA was initially very high and was not affected by ambient nitrate (0.1–5 mol m‐3) for about 10 h. Actual and potential leaf NRA became equal after the same period of time. In the course of nitrate nutrition, the two nitrate reductase activities in leaves were differentially inhibited by cycloheximide (3.6 mmol m‐3) and tungstate (1 mol m‐3). We suggest that initial potential NRA reflects the activity of pre‐existing enzyme, whereas actual NRA depends on enzyme assembly during NO3‐ supply.Apparent induction of nitrate uptake and most (85%) of the actual in vivo NRA occurred in the root system during the first 6 h of nitrate utilization by dwarf bean.
Temperature Sensitivity of Daily Respiratory Patterns Entrained through Phytochrome Action in Lemna paucicostata Strain 6746
Authors: HILLMAN WILLIAM S. 
Published: April 2006

AbstractThe respiration rate of heterotrophic Lemna paucicostata Hegelm. 6746 cultures at 26–27°C and given a brief pulse of red light, assumes patterns with properties dependent on the nitrogen source supplied. In a search for conditions specifically affecting features of those patterns expressing photperiodic timing, their amplitudes have been measured as relative peak height (RPH) — the increased height at the daily peak as a proportion of the average daily minimum — at both 21°C and 28°C. On nitrate, ammonium or aspartate medium, RPH is reduced roughly 70% at 21°C as compared to 28°C, but on nitrogen‐deficient medium the reduction is only 20–30%. Yet growth and the actual intensity of respiration are not differently temperature sensitive on NO3 and N‐deficient media. Nor does RPH itself correlate with growth rate.Previous evidence indicates that patterns on NO3 and NH4 media reflect photoperiodic timing and that those on aspartale and N‐deficient media do not; hence the temperature sensitivity of RPH does not correlate with whether or not a pattern reflects photo‐periodic timing. However, different daily patterns arc elicited by pulses of red or far‐red on NO3. NH4 and aspartale media but not on the N‐deficient. Hence the temperature sensitivity of RPH does correlate with the degree to which the patterns distinguish between red and far‐red, which is to say between high anti low levels of Pfr‐phytochrome. This suggests that high temperature sensitivity in RPH reflects a reaction limited by N assimilation and saturating only at relatively high levels of Pfr.
Imaging by Delayed Light Emission (Phytoluminography) as a Method for Detecting Damage to the Photosynthetic System
Authors: BJÖRN L. O. , FORSBERG A. S. 
Published: April 2006

AbstractAn improved apparatus for obtaining luminescence (delayed light emission) images of plants is described. It consists of a phosphoroscope equipped with an imaging lens and an electronic image intensifier. It is also equipped with light‐sources for obtaining images with reflected light and fluorescence light.It is shown that damage to the photosynthetic system caused by virus, insects, high or low temperature, ultraviolet radiation, or herbicide, and also chioroplast senescence as part of a normal developmental process, can be followed by this non‐destructive method. In many cases changes which are not visible in fluorescence images are clearly seen in luminescence images.
Epicuticular Wax and Cuticular Resistance in Rice
Authors: O'TOOLE J. C. , CRUZ R. T. , SEIBER J. N. 
Published: April 2006

AbstractHigh leaf cuticular resistance has been reported as a component adaptation of plants to drought prone regions, Experiments were conducted to evaluate and characterize the role of epicuticular wax as a component of cuticular resistance to water vapor loss from rice (Oryza sativa L.) leaves. This information is necessary to determine the applicability of including higher cuticular resistance in an upland rice breeding program and to evaluate potential selection methods.Diffusion porometry, electron microscopy, and gas liquid chromatography were employed. Measurement of cuticular resistance by leaf diffusive resistance porometry after stomatal closure by exposure of rice leaves to pure CO2 for 15 min was found sufficient to induce complete stomatal closure regardless of light level, and was superior to dark acclimation for this purpose.Removal of epicuticular wax from rice leaves by chloroform dip significantly reduced the cuticular resistance. Stressed plants were observed to increase cuticular resistance, illustrating the responsive nature of this characteristic.Gas liquid chromatography (GLC) of the chloroform leaf dip proved to be an expedient method of characterizing both quantitative and qualitative differences in the epicuticular wax of rice cullivars. The porometry and GLC techniques may be useful in selecting parents, spot checking in a pedigree program, or checking lines reaching the yield testing stage, but ate not well suited lor mass screening early generation progeny.Significant differences were found in the two rice cultivurs, ‘63–83′, an upland adapted rice from West Africa, and “IR20′, bred and selected in submerged paddy culture in ihc Philippines, by tlie above methods of characterizing cuticular resistance and epicuticular wax. These results are of ecological significance to plant breeders.
Inhibitory Action of Blue and Far‐Red Light in the Flowering of Lemna paucicostata
Authors: OHTANI TAKESHI , ISHIGURI YOSHIO 
Published: April 2006

AbstractIn a new strain of short‐day duckweed (Lemna paucicostata T‐101), blue and far‐red light‐induced inhibition of flowering was investigated. Flowering of this strain failed to be induced under a short‐day photoperiod of blue and far‐red light, although it responded as a typical short‐day plant in red and white light. When the short‐day photoperiod of blue or far‐red light was terminated by a 15 min red light pulse, flowering recovered completely. This inducing effect of red light was reversed by subsequent exposure to far‐red light. Furthermore, it could be demonstrated that 30 min of blue light completely reversed the flowering inductive effect of 5 min red light and vice versa. Evidence is presented suggesting that the inhibitory action of blue and far red light may be due to the lowering of phytochrome Pfr levels below those required to start the dark reactions which lead to flowering. These results are discussed in relation to the time measurement system of photoperiodism.
The Different Components of the Movement and the Areas of Retention of Labelled Molecules after Application of [3H]‐ indolyl‐acetic acid to the Apical Bud of Vicia faba
Authors: BOURBOULOUX ANDREE , BONNEMAIN JEAN‐LOUIS 
Published: April 2006

AbstractAfter application of [3H]‐auxin (0.8 nmol) to a young leaf of Vicia faba L. cv. Aguadulce. about 6% (1.1 × 10‐2 nmol) of applied IAA enters the stem during the first 6 h of transport. This corresponds to a [3H]‐auxin flux which is probably not very different from the endogenous flux. A wave of [3H]‐ auxin moves down to the roots mainly among preferential pathways situated in the vascular bundle. This movement is accompanied and followed by certain events: (I) In the upper part of the stem, some radioactive molecules leave the pathways of polar transport and enter the young leaves near the donor leaf. (2) In other parts of the stem, the auxin transport is highly polar. As the peak of the wave approaches and passes a node with an axillary bud. and for a few hours afterwards, there is no clearly detectable radioactivity in this bud, although the nodal tissues are very radioactive. (3) A retention of labelled molecules often occurs in the nodes. (4) Retention of label is regularly seen in the basal part of the first internode and in the hypocotyl, which together form that part of the axis where Ifle highly inhibited cotyledonary buds are found. This retention is still manifest a week after the downward transport of [3H]‐auxin. (5) After 48 h. a high proportion (about 45%) of the [3H]‐auxin exported by the donor leaf is found in the roots. (6) Subsequently, a part of the label returns to the upper parts of the plant, and especially to the leaves, where it normally appears to be immobilized. (7) As time goes on some labelled molecules, probably coming from different areas, enter the axillary buds.
14CO2 Fixation and Compartmentation of Carbon Metabolism in a Recombined Chloroplast‐ ‘Cytoplasm’ System
Authors: LARSSON CHRISTER 
Published: April 2006

AbstractThe Compartmentation of 14CO2 fixation and concomitant metabolism of l4C‐iabelled products in a recombined system, composed of isolated intact spinach (Spinacia oleracea) chloroplasls and a ‘cytoplasm’ fraction, has been studied. Addition of ‘cytoplasm’ to chloroplasts fixing 14CO2 increased the label in hexoae monophosphates outside the chloroplasts at the expense of excreted dihydroxyacetone phosphate. The label in ammo acids was increased both inside and outside the chloroplasts. The results support the view that chloroplasls are not able to make 2‐oxoacids for amino acid synthesis directly from fixed CO2, but have to co‐operate with the cytoplasm and other organelles. The results also show that recombined systems can be useful for studies on the compartmen tation of carbon metabolism in pholosynthesizing plant tissues.
Self inhibition of the Agaricus bisporus Spore by CO2 and/or γ‐Glulaminyl‐4‐hydroxybenzene and γ‐Gtutaminyl‐3,4‐benzoquinone: A Biochemical Analysis
Authors: RAST DORA , STÜYSSI HANS , ZOBRIST PETER 
Published: April 2006

AbstractChemical and enzymological analyses have been carried out to study the mode of action of CO2, in inhibiting germination in Agaricus bisporus and to test the suggestion (Vogel and Weaver, 1972. Exp. Cell Res. 75: 95, Vogel et at, 1974. Am. J. Pathol. 76: 165) that γ‐glutaminyl‐4‐hydroxybenzene (GHB) and/or γ‐glutaminyl‐3,4‐benzoquinone (GBQ) would inhibit the succinate dehydrogenase (SDH) in the mushroom spore and thus represent the causal agent(s) of its dormancy. Evidence is presented that the impairment of SDH is brought about by Ihe CO, fixation product oxaloacelate which is formed in the pyruvate carboxylase reaction, and a mechanism is proposed for the release of the SDH inhibition when activating the spores. These are almost devoid of GHB, whereas fruit bodies of all developmental stages contain considerable amounts of the phenol. GBQ is absent in the spore, and its occurrence in mushroom fruit body extracts appears to be an artifact of extraction. Apart from these analytical results, theoretical reasons are given that vouch against the involvement of the phenolics in the inhibition of SDH in vivo.
Effects of Brassin‐Complex on Auxin and Gibberellin Mediated Events in the Morphogenesis of the Etiolated Bean Hypocotyl
Authors: YOPP JOHN H. , COLCLASURE G. CRAIG , MANDAVA NAGABHUSHANAM 
Published: April 2006

AbstractThe excised, hooked bean hypocotyl was the system used to determine wheiher the ‘auxin‐ and gibberellin like’ effect of the lipoidal pollen extract, Brass in‐complex (Br), were mediated through, or independent of, auxin and gibberellin. The morphogenetic events of hook opening and hypocotyl elongation in this system are regulated by auxin and gibberellin, respectively.Brassin complex, like IAA, elicited a book closure in (he dark and retarded its opening in red light. This effect was synergized by T1BA, IAA and the presence of the auxin‐producing organs, the epicotyl and cotyledons. Br‐elicited hook closure was inhibited by the antiauxin. PCIB.Both GA3 and Br totally reversed the light inhibition of hypocotyl elongation. The GA3‐effect, but nol the Br elicited elongation, was overcome by Ancymidol. Hypocotyl elongation was partially inhibited by TIBA and PCIB. suggesting a possible auxin involvement also in this effect of Br.Br may elicit its growth responses through an effect on endogenous auxin levels, In this way it is different from other lipoidat growth regulators, such as the oleanimins which require the presence of exogenous growth regulators for activity.
Genetic Analysis in Wood‐Decaying Fungi I. Genetic Variation and Evidence for Allopatric Speciation in Pleurotus ostreatus using Phenoloxidase Zymograms and Morphological Criteria
Authors: PRILLINGER HANSJÖRG , MOLITORIS H. PETER 
Published: April 2006

AbstractUsing electropherograms (zymograms) of the phenoloxidase laccase and characteristics of mycelial growth and fruit body production, a distinct morphological and biochemical differentiation of two geographically isolated (allopatric) populations of the wood‐rotting basidiomycete Pleurotus ostreatus became evident. No limitation in their outbreeding ability was observed, however. A specific secretory mechanism for an extracellular laccase, genetically different in the two geographical races, could be detected. An approximately 1: 1 segregation of this laccase band in the F1 generation indicates that specific secretion of this enzyme is controlled by one gene only, Different degrees of genetic variation as shown by differences in the respective laccase spectra were found in the two geographical races. Only one enzyme band out of nine multiple laccases was found to be specific for fruit bodies. The value of zymograms for chemotaxonomic purposes, for the understanding of microevolution and for determination of genetic variation in fungi is critically discussed.