bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the initial stages of plant protoplast development using 33258 Hoechst: reactivation of the cell cycle
Authors: Galbraith David W. , Mauch Teri J. , Shields Barbara A. 
Published: April 2006

A microfluorimetric procedure, employing the fluorescent stain 33258 Hoechst, has been developed for the investigation of the process of DNA synthesis during the initial stages of culture of tobacco (N. tabacum cv. Xanthi) leaf protoplasts.In this system, the freshly‐isolated protoplasts exhibited a unimodal distribution of nuclear DNA content characteristic of the diploid state. The almost immediate onset of DNA synthesis during culture resulted in a doubling of nuclear DNA levels prior to the first mitoses. Although the majority of the protoplasts subsequently entered into synchronous mitosis and cell division, a proportion of the remainder developed into large polyploid cells. Upon further culture, the polyploid cells became subdivided into clusters of small diploid cells. Measurement of total cell protein and cell volumes during culture indicated that a relationship existed between these parameters and the initiation of mitosis. The significance of these observations is discussed.
The lag‐phase of potassium translocation from the root to the shoot of low‐salt barley plants. Kinetic and localization studies
Authors: Van Iren Frank , Joolen M. Lonlou , Gerritsen Anton F. C. , Noordervliet Marcel A. W. , der Sluijs F. Pinie Boers‐Van 
Published: April 2006

In roots of low‐salt barley (Hordeum vulgare L.), translocation of K+, as well as of several other ions, from the root to the shoot starts after a lag‐time. Its length is independent of external concentration. The onset of upward translocation can be remarkably abrupt. Three hypotheses that could explain the lag‐phase were tested:

It is the result of successive loading of the concentric root cell layers centripetally from the epidermis.
It is the result of successive loading of the root basipetally from the apex.
It is the result of induction of the mechanism(s) responsible for upward translocation.

All three hypotheses are rejected. Within the whole root radial as well as longitudinal equilibration appears to be very rapid. The simple model of compartmentation is rejected. A more complex compartmentation of the cytoplasm (symplasm) in which the endopiasmic reticulum could play a predominant role is suggested. The mechanisms of vacuolar accumulation and upward translocation appear biochemically related.
Effects of salinity and replacement of K+ by Na+ on lipid composition in two sugar beet inbred lines
Authors: Stuiver C. E. E. , Kuiper P. J. C. , Marschner H. , Kylin A. 
Published: April 2006

The effects of NaCl and replacement of K+ by Na+ on the lipid composition of the two sugar beet inbred lines FIA and ADA were studied (a) with increasing additions of NaCl to the basal medium, and (b) with increasing replacement of K+ by Na+ at the same total concentration as in the basal medium. Direct relations were noted between NaCl concentration of the nutrient solution and the phospholipid concentration in the roots of FIA, the genotype characterized by a low K+/Na+ ratio, as well as between NaCl in the medium and the phospholipid concentration in the shoots of ADA, the genotype with a high K +/Na + ratio. The sulfolipid level in the roots of FIA was maintained at higher NaCl concentrations, while it was decreased in ADA. The glycolipid concentration in the shoots of ADA and the degree of unsaturation of the fatty acids of the total lipid fraction were decreased by salinity, indicating reduced biosynthesis of chloroplast glycolipids and/or accelerated oxidation of these lipids in the presence of NaCl.In the Na+ for K+ replacement experiment a low content of K+ in the medium resulted in decreased levels of total lipids, phospholipids and sulfolipid in the roots of both genotypes, which did not relate to root growth. K+‐leakage from the roots at low K+‐level in the medium may be reduced by the increase in saturation of the lipids. In the shoots of ADA increased levels of total lipids, phospholipids and Sulfolipid were noted at a low K+‐concentration of the nutrient solution.
Transport of Mg2+ and Ca2+, and Mg2+‐stimulated adenosine triphosphatase activity in oat roots as affected by mineral nutrition
Authors: Stok Bert P. , Tànczos Otto Gy. , Kähr Monika , Bep Stuiver C. E. E. , Kylin Anders , Kuiper Pieter J. C. 
Published: April 2006

Mg2+‐ and Ca2+‐uptake was measured in dark‐grown oat seedlings (Avena sativa L. cv. Brighton) cultivated at two levels of mineral nutrition. In addition the stimulation of the ATPase activity of the microsomal fraction of the roots by Mg2+ was measured. Ca2+‐uptake by the roots was mainly passive. Mg2+‐uptake mainly active; the passive component of Mg2+‐uptake was accompanied by Ca2+‐efflux up to 60% of the Ca2+ present in the roots.In general Mg2+ ‐uptake of oat roots was biphasic. The affinity of the second phase correspond well with that of the Mg2+‐stimulation of the ATPase activity, in low‐salt roots as well as in high‐salt roots and in roots of plants switched to the other nutritional condition. Linear relationships were observed when [phase 2] Mg2+‐uptake was plotted against Mg2+‐stimulation of the ATPase activity of the microsomal fraction of the roots. In 5 days old high‐salt plants 1 ATP (hydrolysed in the presence of Mg2+ J corresponded with active uptake of a single Mg2+ ion, but in older high‐salt roots and in low‐salt roots more ATP was hydrolysed per net uptake of a Mg2+ ion. The results are discussed against the background of regulation of the Mg2+‐level of the cytoplasm of root cells by transport of Mg2+ by a Mg2+‐ATPase to the vacuole, to the xylem vessels, and possibly outwards.
Osmotic adjustment in indoor grown cassava in response to water stress
Authors: Ike I. F. , Thurtell G. W. 
Published: April 2006

The water content‐water potential relation in stressed and unstressed cassava (Man‐ihot species) was examined to ascertain (i) the magnitude of osmotic adjustment in response to water stress and (ii) the mechanisms of such adjustments.Water stress resulted in a displacement of the water content‐potential relation such that at any leaf water potential the water content was higher in the stressed plants. The osmotic potentials of turgid leaves (100% relative water content) were ‐0.97 and ‐1.00 MPa in the unstressed cultivars CMC 9 and MCOL 113 respectively. In the stressed plants, the values were‐1.13 MPa (CMC 9) and‐1.14 MPa (MCOL 113). The 0.14 to 0.16 MPa osmotic potential difference between the stressed and unstressed plants suggests that a stress‐induced osmotic adjustment occurred in both cultivars. The biiSk volumetric elastic moduli at turgor pressures above 0.10 MPa were 9.84 MPa (CMC 9) and 13.58 MPa (MCOL 113) in the unstressed plants. Tbe higher values found in the stressed plants, 14.56 MPa in CMC 9 and 16.91 MPa in MCOL 113, suggest a stress‐induced decrease in cell wall elasticity. Hence, the observed shift in the wafer content‐potential relations in the cassava involved both an osmotic adjustment and a decrease in cell wall elasticity. Increasing the number of stress cycles per plant did not cause a further displacement of the water content‐potential curves.
Frost hardiness development in Pinus silvestris seedlings in response to fertilization
Authors: Hellergren J. 
Published: April 2006

The effects of different levels of nitrogen on freezing survival, the amounts of chlorophylls and β‐carotene, the ratios Chl a/Chl b, and (Chl a + Chl b)/β‐carotene in hardened and unhardened seedlings of Scots Pine (Pinus silvestris L.) have been investigated. There was. no correlation between frost hardiness and nitrogen content in the unhardened seedlings. However, the hardy seedlings with the highest nitrogen content, showed a decrease in frost hardiness of 3°C. The amounts of chlorophylls and β‐carotene increased for all the treatments during hardening, except for the seedlings that had the highest nitrogen content; so that the effect of fertilizer was more evident in non‐hardened than in hardened plants. The ratios Chl a/Chl b decreased during hardening in all the treatments. This was an effect of a larger increase of Chl b than Chl a. The ratios of Chl a + Chl b/β‐carotene also decreased during hardening except for the plants that were fertilized with the second lowest amount of nitrogen. Since the amounts of Chl a and Chl b increase during hardening the amount of β‐carotene increases even more.The growth rates of the seedlings were closely related to the nitrogen content for the different treatments. All plants were infected with ectotrophic mycorrhizae, which resulted in an enhancement of ion transportation from the soil to the plants. This is important when the supply of ions is low.
Incorporation of label from root‐applied N6[8‐14C]furfiuryIadenine into the guanine nucleotide fraction of pea bud ribonucleic acid
Authors: Morris David A. 
Published: April 2006

The pattern of incorporation of label into the nucleotides of axillary bud ribonucleic acid was investigated in Pisum sativum L. cv. Meteor following the application of N6[8‐I4C]furfuryladenine or of [8‐14C]adenine to the root system of decapitated plants and to cultured excised buds. When N6[8‐14C]furifaryladenine was applied to the root system label was confined to the guanine nucleotide moiety of the axillary bud ribonucleic acid; label from [8‐14C]adenine was incorporated preferentially into adenine nucleotide in the molar ratio adenine nucleotide/guanine nucleotide = 3.23. When isolated buds were incubated in media containing [8‐14C]adenine or N6[8‐14C]furfuryladenine, label was incorporated into both purine moieties of the ribonucleic acid. However, the relative incorporation into the guanine nucleotide fraction was considerably greater for N6[8‐I4C]furfuryladenine (adenine nucleotide/guanine nucleotide = 2.23) than for [8‐14C]adenine (ratio = 4.67).It was concluded that the pattern of metabolism of adenine to guanine and its incorporation into the guanine nucleotide moiety of pea axillary bud ribonucleic acid, is influenced by the presence of a substitution in the N6 position of the adenine base.
Potassium transport in wheat seedlings grown with different potassium supplies
Authors: Bérczi Alajos , Oláh Zoltán , Fekete Attila , Erdei László 
Published: April 2006

Wheat seedlings (Triticum aestivum L. cv. Martonvásári 8) germinated and grown with different K+ supplies in a complete nutrient solution were examined. As controls, plants were grown in tridistilled water and 0.5 mmol/dm3 CaSO4 solution. The ionic states of the roots and shoots were followed from the 3rd to the 11th day after germination, with daily measurement of their K, Na, Mg and Ca contents. On the 11th day the K+(86Rb) influx of the excised roots was determined in the presence or absence of Ca2+ in an uptake solution of 1 mmol/dm3 KCl. The water contents of the plants and the K, Na, Mg and Ca contents of the excised roots were also measured before and after the uptake experiments of 1 h.The rate of growth of the seedlings was practically independent of the ionic supply during the first 6 days. By the 7th and 11th days all plants (even those grown in tridistilled water) had reached the one‐leaf and the two‐leaf stage, respectively, but the water content of the roots of the control plants (about 86%) was significantly lower than that of other plants (about 95%). The lowest K content of wheat roots can be estimated as about 200 μmol (g dry weight)−1, which is about 10 μmol (g fresh weight)−1. Potassium seemed to be partly replaced by sodium. At high K contents in the roots and shoots, Na and Mg are expelled from both and, in addition, Ca is expelled from the shoots. The Ca content of the roots seemed to be unaffected by the K+ supply (or K content). The K+(86Rb) uptake of excised roots is interpreted on the basis of the negative feedback regulation by the K content of the roots. A possible Ca2+‐K+ exchange is also outlined.
Contrasting effects of simazine on the photosynthetic physiology and leaf morphology of two Populus clones
Authors: Akinyemiju O. A. , Dickmann Donald I. 
Published: April 2006

Differential effects of simazine (2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine) on the physiology of two Populus clones were investigated in a greenhouse study. Additions of 5 mg/pot simazine to young plants had no deleterious morphological or physiological effects on clone NC 5328 (P. x euramericana cv. I 45/51; Section Aigeiros), but reduced the rate of CO2 fixation, increased CO2 compensation concentrations and lowered the specific leaf weight of clone NE 388 (P. maximowiczü x P. trichocarpa cv. Kingston; section Tacamahaca). Abaxial leaf conductance to water vapor was not affected in NE 388. Deleterious effects of simazine on NE 388 were detected ca 48 h after exposure of plants to simazine and generally became more pronounced thereafter. Visual symptoms of injury were evident at ca 2 weeks after simazine application.Toxic responses to simazine in clone NE 388 varied in different portions of the crown. Inhibition of photosynthesis and increased CO2 compensation concentrations were more pronounced in the region of recently matured leaves, but were somewhat less in the region of expanding leaves. Older mature leaves in the lower crown region showed no visual symptoms of injury and the rate of photosynthesis and CO2 compensation concentrations were largely unaffected.
Relation of source and sink during grain filling period in wheat and some aspects of its regulation
Authors: Herzog H. 
Published: April 2006

The effects of changes in source‐sink relation and of cytokinin applications were examined with regard to the development of flag leaves and grain growth in two contrasting spring wheats, Triticum aestivum L., cv. Kolibri and Solo, grown in hydroculture at mean day/night temperatures of 21/19°C.Lowering temperatures during the phase of ear differentiation decreased the ratio of source and sink size (flag leaf area/grains per ear) but hardly affected maximum chlorophyll content of the flag leaf (source activity), maximum rates of grain growth (sink activity), or final grain weight. Nevertheless, considerable differences were produced with regard to the duration of grain filling, the development and coordination of source and sink activities after maxima had been attained.Changing the ratio of source and sink size during grain filling by spikelet removal affected final grain weight the less, the later the treatments began. Comparing, plants with identical source activities demonstrated that differences in grain weight were mainly due to different growth rates between day 16 and 40. Source activities were raised only temporarily (day 23) by spikelet removal done at day 2 or 14.From this it may be concluded that changing the ratio of source and sink size influenced grain weight by creating different intrinsic growth potentials in the grains. These potentials might be estimated 3 weeks after ear emergence by DNA and RNA content per grain.The effects of exogenous cytokinins were consistent with those due to spikelet removal suggesting that this hormone participates in a joint regulation of source and sink activity during grain filling.
Chlorophyll‐protein levels and degree of thylakoid stacking in radish chloroplasts from high‐light, low‐light and bentazon‐treated plants
Authors: Lichtenthaler Hartmut K. , Kuhn Gertrud , Prenzel Ursula , Meier Dieter 
Published: April 2006

The level of 7 chlorophyll‐carotenoid‐proteins was determined in chloroplasts from radish seedlings (Raphanus sativusL. var. Saxa Treib) grown in high‐light (HL; 90 W m−2and low‐light (LL; 10 W m−2) growth conditions with and without application of the photosystem 2 herbicide bentazon (10−4M) and compared with the degree of thylakoid stacking.The photosynthetic apparatus of HL‐chloroplasts contains higher proportions of the photosystem 1 chlorophylla‐proteins CPI and CPIa than LL‐chloroplasts or chloroplasts from bentazon‐treated plants.In LL‐chloroplasts and in chloroplasts from bentazon‐treated plants a higher proportion of light‐harvesting chlorophylla/b‐proteins (LHCP1, LHCP2, LHCP3, LHCPy) is found. Bentazon treatment changes the proportion of LHCPs to about the same levels under both HL and LL‐growth conditions. The amounts of free chlorophyll found in bentazon chloroplasts (27–29%) is higher than in the HL or LL‐controls (16–18%).The increase in degree of thylakoid stacking (% proportion of appressed membranes per total chloroplasts membranes) of LL‐chloroplasts as compared to HL‐chloroplasts of 7 to 9% (3rd to 5th day of illumination) is paralleled by a similar increase in the LHCPs of 5% and 8% (3rd and 5th day). The importance of light harvesting chlorophylla/b‐proteins as a prerequisite for thylakoid stacking is discussed.
Le transport basipète de l'AIA‐5‐3H dans le coléoptile de blé
Authors: Perbal Gérald , Driss‐Ecole Dominique , Leroux Yves 
Published: April 2006

Basipetal transport of [5‐3H] IAA in the wheat coleoptile 3H‐IAA was applied to the tips of intact wheat coleoptiles (Triticum sativum L., var. Capitole) for 30, 60 or 120 min. The quantity of label per segment (1.5 mm), determined by liquid scintillation counting, was a decreasing exponential function of distance from the source of radioactivity. Chromatographic analysis showed that 3H‐IAA was transported more rapidly than its tritiated metabolites. Antoradiographs of semi‐thin sections were performed after application of 3H‐IAA during 2 h and after treatment by DCC [1‐(3‐dimethyl‐aminopropyl)‐3‐ethycarbodiimide hydrochloride]. The quantity of label per tissue and per cell was determined at 1.5, 3.0 and 4.5 mm from the tip. Tritiated IAA was estimated to account for 70 to 100% of the label, depending on the distance from the tip. The amount of auxin transported basipetally was greatest in the parenchyma, with lesser amounts transported in the inner and outer epidermis. Tissues of the vascular bundles did not contain more than 10% of total radioactivity of the coleoptile sections. The rate of auxin transport was greater in xylem and parenchyma than in epidermis and bundle sheath. Movement was very slow in procambium and phloem. In parenchyma and epidermis the quantity of label per cell as a function of distance from the tip agreed with the model of exponential regression. These results support the theory of polar diffusion of auxin.
Synthèse et hydrolyse du saccharose dans l'œillet alimenté avec une solution glucosée
Authors: Paulin André , Droillard Marie‐Jo 
Published: April 2006

Sucrose synthesis and sucrose hydrolysis in cut carnations (Dianthus caryophyllus) supplied with glucose solution.Sucrose synthesis and hydrolysis in cut carnations supplied with a glucose solution have been investigated using both entire floral branches and floral branches without any of their organs (petals, non‐petaloid pieces, leaves) and isolated organs. – The flower is a more active sink that the leaves. The transformationn of glucose into sucrose is essential for the ability of the flower to use the exogenous glucose. All organs of the floral branch (petals, ovaries and sepals, leaves, stem) are able to form sucrose. The hydrolysis of the obtained sucrose occurs nearly exclusively in the petals.
Gas exchange in a 20‐year‐old stand of Scots pine
Authors: Troeng E. , Linder S. 
Published: April 2006

Net photosynthesis of current and one‐year‐old shoots in Scots pine (Pinus sylvestris L.) was measured during a two‐year period (1977–1978). The measurements were carried out in Central Sweden using a system that allowed in situ measurements throughout the year. The photosynthetically active period, defined as months with a positive carbon dioxide balance, was nine months per year for one‐year‐old shoots and six months for current shoots. The daily rates of net photosynthesis were low in spring and late autumn and 95% of the annual photosynthetic production occurred from May to October. In spring net photosynthesis was limited by a low photosynthetic capacity and a restricted access to water caused by the frozen ground. It took more than three months in spring and early summer to restore full photosynthetic capacity in the one‐year‐old shoots, but the rate of recovery varied considerably between the two years. In late autumn the rates of photosynthesis were mainly limited by low photon flux densities.The seasonal patterns of photosynthesis were similar between the two years, and even though there were pronounced differences for individual months, the total annual photosynthetic production of the two years only differed by 1.4% for the one‐year‐old shoots. The differences in photosynthetic production for current shoots were much higher as an effect of different rates of needle development and differences in photosynthetic capacity during the two years. An estimate of the carbon balance of the current shoots showed that the shoots had not photosynthesized their own weight in terms of carbon until late August (1978) or early September (1977), which means that their photosynthetic production was of minor importance for the formation of stem wood.
Influence de l'intensité et de la longueur d'onde de la lumière sur le rendement des radicaux libres dans les semences de tomate et de carotte
Authors: Khoury A. , Dannaoui S. D. , Ouaida A. F. , Chetverikov A. G. , Stanko S. A. 
Published: April 2006

Influence of light intensity and wavelength on the yield of free radicals in seeds of tomato and carrot. Seeds of tomato (Lycopersicum esculentum L. cv. Gribovsky‐1180) and carrot (Daucus carota L. cv. Santanet) were irradiated by continuous light of different wavelengths (white, blue, green, red, far‐red and He‐Ne laser) and different power density. Free radical output was measured using Electron Spin Resonance spectra (ESR). The dependence of the content of free radicals (FR) on the light power density was established. The yield of FR in the seeds irradiated with monochromatic light of the same power density was inversely proportional to the wavelength. The ESR spectra showed maximum absolute number of FR for white light. Successive irradiations gave cumulative effects on the output of free radicals in both directions: increase by the action of white light and decrease by the action of red and far‐red light. The contact of irradiated seeds with steam decreased the amount of FR.