bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions between myo‐inositol and cytokinins: Their basipetal transport and effect on peach roots
Authors: Gur Arye , Altman Arie , Stern Rafael , Sigler Tomy , Wolowitz Brenda 
Published: May 2006

Root growth of partly defoliated young peach seedlings [Prunus persica (L.) Batsch. cv. Lovell] was significantly promoted by application of myo‐inositol to the cut surface of the stem. Addition of benzylaminopurine (BA) combined with sucrose enhanced the promotive effect of myo‐inositol on root growth, but addition of sucrose alone, suppressed it. Spraying rooted peach cuttings (nectarine cv. Sunred) with myo‐inositol and defoliating them after 5 days increased the incorporation of amino acids into proteins in excised roots, obtained from the sprayed plants, as compared with roots from plants sprayed with water, or sucrose, or sucrose + myo‐inositol. Myo‐inositol applied in combination with kinetin or BA to stems of young peach seedlings (cv. Lovell) or rooted peach cuttings (cv. Almog) promoted the basipctal translocation of the two cytokinins in the stem and acropetally into the small lateral roots. Addition of sucrose voided this effect on the cytokinins. BA, when applied together with myo‐inositol, was partly converted into an additional cytokinin‐active compound in the roots.Application of BA to either roots or tops of rooted peach cuttings (cv. Almog) resulted in the accumulation of myo‐inositol (supplied through the cut surface of the stem) in the plant part to which BA had been applied.
Accelerated ethylene production as related to changes in lipids and electrolyte leakage during senescence of petals of cut carnations (Dianthus caryophyllus)
Authors: Sylvestre I. , Paulin A. 
Published: May 2006

Conditions inhibiting the action of (supply of silver thiosulfate) or the synthesis of (supply of α‐aminooxyacetic acid) ethylene, prolonged the vase‐life of carnation (Dianthus caryophyllus L. cv. Ember) flowers. On the other hand, conditions which provoked an advance in the time of appearance of the ethylene rise (previous exposure to exogenous ethylene), accelerated senescence. This action on the morphological changes was accompanied by an effect on the efflux of electrolytes, which was advanced or delayed depending on the type of treatment, in comparison with the control.The various factors acting on ethylene production also affected membrane lipids. Those which suppressed or delayed the ethylene rise, slowed down the degradation of the total and free fatty acids and the increase in the level of saturation of the chains. The opposite was observed when the ethylene peak occurred early. There was no correlation between the time of appearance of the burst of ethylene and the time of onset of lipid breakdown.A 48 h water stress provoked neither an advance in the time of appearance of the ethylene peak nor an acceleration in lipid breakdown on return to normal conditions.
Abscisic acid metabolism in Ceratocystis coerulescens
Authors: Kettner Jens , DörfOing Karl 
Published: May 2006

The fungus Ceratocystis coerulescens Bakshi (strain RWD 390) has been shown to produce the plant hormone, abscisic acid (ABA). The production of ABA in defined liquid medium during a culture period of 50 days was measured by gas‐liquid chromatography. A considerable accumulation of ABA occurred in the stationary phase. Maximum ABA contents were 3.5 ng ml−1 in culture media and 218 ng (g dry weight)−1 in mycelial extracts.The ABA‐metabolizing capability of the fungus was investigated. Dihydrophaseic acid, and phaseic acid, ABA metabolites in higher plants, were not present in cultures of Ceratocystis coerulescens. When [2‐14C]‐ABA was fed to the fungus, the formation of [2‐14C]‐2‐trans, 4‐trans‐ABA and a second metabolite, less polar than ABA, was observed. This suggests a different metabolic pathway of ABA in the fungus.
Distribution of 14C assimilates in the storage root of sugar beet plants after import from leaves of different age
Authors: Haeder H. E. , Beringer H. 
Published: May 2006

In the sugar beet plant (Beta vulgaris L. ssp. altissima) the vascular bundles of old leaves lead to the center and those of young leaves to the periphery of the storage root. Whether the flux of assimilates follows these anatomical routes was tested by applying 14CO2 for 4 h to either an old (10th) or a young (20th) leaf in intact sugar beet plants. Four‐month‐old plants, which had about 30 leaves, were used in the experiment. The 14C distribution in the storage root was measured by autoradiography and counting in about 20 cross and longitudinal sections per root.About 37% of assimilated 14C from an old leaf and 23% from a young leaf were exported within 24 h. Although some 14C moved into younger leaves, most was exported into the storage root. During its rapid movement towards the root tip, which took place perferentially in the orthostichon belonging to the [14C]‐treated leaf, the label spread laterally.The autoradiograms indicate that the distribution of assimilates within the storage root is roughly determined by the course of the vascular bundles extending from the source leaf. The fine distribution, however, seems to be controlled by sucrose gradients between storage cells.
Plant responses to H2S and SO2 fumigation. I. Effects on growth, transpiration and sulfur content of spinach
Authors: Maas Frank M. , de Kok Luit J. , Hoffmann Ingrid , Kuiper Pieter J. C. 
Published: May 2006

Exposure of spinach (Spinacia oleracea L. cv. Monosa) to 0.25 μl l−1 H2S reduced the relative growth rate by 26, 47 and 60% at 15, 18 and 25°C, respectively. Shoot to root ratio decreased in plants fumigated at 18 and 25°C. Growth of spinach was not affected by a 2‐week exposure to 0.10 or 0.25 μl l−1 SO2.Both H2S and SO2 fumigation increased the content of sulfhydryl compounds and sulfate. A 2‐week exposure to 0.25 μl l−1 H2S resulted in an increase in sulfhydryl and sulfate content of 250 to 450% and 63 to 248% in the shoots, respectively, depending on growth temperature. Exposure to 0.15 and 0.30 μl l−1 H2S at 20°C for 2 weeks resulted in a 46% increase in sulfate content of the shoots at 0.30 μl l−1 and no detectable increase at 0.15 μl l−1 H2S; the sulfate content of the roots increased by 195 and 145% at 0.15 and 0.30 μl l−1 H2S, respectively. Fumigation with 0.25 μl l−1 SO2 at 20°C for 2 weeks resulted in an increase in sulfhydryl content and sulfate content in the shoots of 285% and 300 to 1100%.H2S fumigation during the 12 h light period or only during the dark period resulted in identical growth reduction and accumulation of sulfhydryl compounds; they were about 50 and 67% of those observed in continuously exposed plants.H2S‐ and SO2‐exposed plants showed an increased transpiration rate, which was mainly caused by an increased dark‐period transpiration. No effect of H2S and SO2 on the water uptake of the plants and the osmotic potential of the leaves was detected. Plants fumigated with 0.25 μl l−1 H2S for 2 weeks were smaller and differed morphologically from the control plants by slightly more abaxially curved leaf margins. Cross sections of the leaves showed smaller cells at the margins and smaller and fewer air spaces. The increased transpiration in the H2S‐exposed plants is discussed in relation to the observed morphological changes.
Seasonal variations in the properties of ribosome assemblies from vegetative buds of Scots pine
Authors: Kupila‐Ahvenniemi Sirkka , Lindfors Aija , Häggman Hely 
Published: May 2006

The amount of total ribosome assemblies extractable from the vegetative buds of 2 m high Scots pine (Pinus sylvestrís L.) plants remained more or less constant throughout the sampling period from September to May. The stability of the ribosomes, the shape of the polysome profiles obtained after sucrose density gradient centrifugation and the clustering of material as seen in the scanning electron micrographs suggested the presence of storage formations during the winter.All samples of isolated ribosomes were able to synthesize proteins in vitro. During midwinter the translation capacity, when calculated on a ribosome unit basis, was about one third of that found in September and May. This reflects not only the occurrence of storage formation during the winter, but also the amount of initiated translation processes at any given time. The decrease in the in vitro translation capacity in the autumn ceases around the end of November. Ribosome activity starts to increase as early as the end of January or beginning of February. It seems that the reactions are triggered either by an endogenous clock or by the change in the daylength.
Transformation of photoinactive to photoactive protochlorophyllide in isolated prolamellar bodies of wheat (Triticum aestivum) exposed to low pH and ATP
Authors: Grevby Cecilia , Ryberg Margareta , Sundqvist Christer 
Published: May 2006

Isolated prolamellar bodies from the etioplasts of dark‐grown wheat (Triticum aestivumL. cv. Walde, Weibull) contain the enzyme NADPH‐protochlorophyllide oxidoreductase. The organisation of this enzyme in a pigment‐protein complex results in fluorescence emission maxima at 633 and 657 nm. Isolated prolamellar bodies stored in darkness for 24 or 48 h at 4°C (pH 7.2) in the presence of NADPH showed a fluorescence emission ratio 657/633 nm around 4 at −196°C. With acidic conditions this fluorescence ratio increased, with an optimum at pH 5.5. Such an increase was even more pronounced in the presence of ATP and NADPH with ratios up to 8, but was completely blocked when the sulfhydryl inhibitor, dithiobis‐nitrobenzoic acid, was added. As shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis the amount of NADPH‐protochlorophyllide oxidoreductase in the prolamellar bodies did not change during storage for 24 or 48 h.The total amount of protochlorophyllide measured in acetone extracts did not change significantly during storage for 48 h. The values were similar for storage at pH 7.2 and 5.5, but at lower pH (around 5) the pigment content decreased to a third.The most plausible explanation for the increase in fluorescence ratio is that low pH and ATP give rise to a change in conformation, which results in transformation of the short wavelength (633 nm) fluorescing protochlorophyllide to the long wavelength (657 nm) fluorescing form.
Features of the intrageneric Alnus‐Frankia specificity
Authors: Weber Assi , Nurmiaho‐Lassila Eeva‐Liisa , Sundman Veronica 
Published: May 2006

Host specificity between local Frankia strains and native alders [Alnus incana (L.) Moench and A. glutinosa (L.) Gaertn.] was evaluated in inoculation experiments. Pure cultures of Frankia, whether originating from A. incana or A. glutinosa, were infective and effective on both host species. These pure cultures were isolated from spore‐negative (Sp−) nodules. From spore‐positive (Sp+) nodules no Frankia isolates were obtained. This strain type resisted all our isolation attempts and therefore crushed nodules had to be used for Sp+ type inoculations.The Sp+ type Frankia populations differed in their host specificity. Sp+ nodules from A. glutinosa were effective on both alder species, but Sp+ nodules from A. incana induced effective nodules only on the original host; on A. glutinosa only small (1‐3mm) prenodule‐like structures were found. Such A. glutinosa plants died on N‐free medium, thus showing that these nodules were ineffective. In the effective nodules the middle cortex was dominated by infected cells filled with vesicle clusters. In the ineffective nodules only a few cortical cells were infected and sporangia predominated in these cells. Surprisingly enough they also contained vesicle‐like structures as demonstrated in electron micrographs.
Phosphorus export from roots to shoots of barley, buckwheat and rape seedlings with different P status
Authors: Schjørring Jan K. , Jensén Paul 
Published: May 2006

Seedlings of barley (Hordeum vulgare L. cvs Salka and Zita), buckwheat (Fagopyrum esculentum Moench) and rape (Brassica napus L. ssp. napus cv. Line) were grown in complete nutrient solutions with 8 or 10 different P concentrations in the range of 0–2 mM. Phosphate export from roots to shoots was determined from the amount of 32P (or 33P) absorbed and exported to shoots in 1 h from a nutrient solution containing 0.1 mM radiolabelled phosphate. P export was also determined in the presence of a metabolic uncoupler (DNP, 2.4‐dinitrophenol) and a protein synthesis inhibitor (CH, cycloheximide).Phosphorus export from roots to shoots reached a maximum at a certain optimum level of phosphorus in shoots and roots, and decreased at both higher and lower P levels. Maxinmm P export was 1.7 ± 0.2 and 4.5 ± 0.5 (mean ±se of the three species) times higher than the P export at the lowest and highest [P]root, respectively. Hill plots as well as plots of the untransformed decreasing P export vs root or shoot P concentrations above the optimum were linear and had high correlation coefficients. The Hill coefficient (nH) based on [P]root, was —7.7 for barley cv. Salka and varied between ‐3.8 and ‐4.5 for the other species. Based on [P]shootot nH was—16.1 for barley cv. Salka, ‐3.7 for barley cv. Zita and ‐6.4 for the two dicotyledonous species. Relative to the amount of P simultaneously absorbed by the root system, the import of P per unit shoot weight decreased linearly over the whole range of shoot P concentrations in the dicotyledonous species. In contrast, the relative import of P per unit shoot weight of the two barley cultivars increased at low levels of [P]shoot and decreased at higher levels. DNP and CH almost eliminated P export from roots to shoots of seedlings with low or high P status. In seedlings with medium P status only 60 to 75% of the P export was affected.
In vitro shoot development of Prunus GF 655–2: interaction between light and benzyladenine
Authors: Baraldi R. , Rossi F. , Lercari B. 
Published: May 2006

Experiments designed to study the effect of light quality and quantity and their possible interaction with benzyladenine (BA) in the control of in vitro proliferation of Prunus insititia Schneider GF 655–2 microcuttings are reported. The action of BA as a promoting factor of shoot formation was expressed only in the presence of light. The concentration response curves for BA‐induced proliferation were very similar under the different light sources, irrespective of proliferation rate values.Shoot formation under blue, far‐red and white light was enhanced by the highest photon fluence rates, while the efficiency of red seemed to be independent of this factor. The results suggest the action of a low‐energy response in the red waveband and under the low photon fluence rates of blue and white. The inhibition of shoot elongation induced by BA in the dark as well as under all light treatments indicates that, while the BA‐induced release from the apical dominance is light dependent. BA inhibition of shoot elongation is entirely light independent.
Chloride and sulphur concentrations in chloroplasts of spinach
Authors: Van Steveninck Reinhard F.M. , Fernando Denise R. , Anderson Christopher A. , Edwards Linton B. , Van Steveninck Margaret E. 
Published: May 2006

Chloride concentrations within individual chloroplasts, the adjacent cytoplasm and nearby vacuoles of spinach mesophyll cells (Spinacea oleracea L. cv. Hybrid 102) were determined by means of electron probe X‐ray microanalysis in the cleavage plane of quench frozen tissue, which was maintained at liquid nitrogen temperatures. The accuracy of quantitative data obtained with this technique is greatly improved by the adoption of a peak to background ratio method and use of carbon slurry standards, which mimic the quench frozen tissue and its X‐ray fluorescence.Chloroplasts were incapable of maintaining relatively high levels of Cl− under conditions of low Cl− availability (zero Cl− or 20 μM Cl− in nutrient solution), and under conditions of Cl− stress (100 or 200 mM Cl−) chloroplasts had only a limited capacity to maintain a Cl− concentration at a level below that of the cytoplasm and vacuole. However, under conditions of Cl− stress the concentration of Cl− in cytoplasm immediately adjacent to chloroplasts was substantially higher than in the chloroplasts or more distant cytoplasm. Thus, Cl− levels in chloroplasts are apparently not as tightly regulated as was suggested by estimates of Cl− concentration based on aqueous isolation of chloroplasts.Levels of S in chloroplasts were relatively high (equivalent to 40–60 mM SO42− in S standards) and constant for all treatments, with the possible exception of lower S levels in chloroplasts of leaves approaching premature senescence as a result of salt stress. It is implied that the stability of the S‐content results largely from its presence in macromolecular components of chloroplasts (sulfolipids and proteins).
Bacteria‐plant interactions in symbiotic nitrogen fixation
Authors: Quispel A. 
Published: May 2006

In the inter‐ and intracellular N2‐fixing symbioses between plants and micro‐symbionts, the development of an endophytic form of the micro‐symbiont is essential. This development includes a series of steps consisting of plant‐bacteria interactions. Considerable progress in the elucidation of these steps has been made by applications of the methods of molecular genetics. Several genes with a role during infection and nodulation have been indicated in Rhizobium and Bradyrhizobium like the common nod genes A, B, C, I and J, and the host‐specific genes nod E, F and H. The nod D gene is the only constitutive gene, and its product is essential for activity of all other nod genes, provided some flavonoids from the root exudate are present as well. Mutants in these genes show phenotypic effects, in which the products of the genes must be involved. Far more difficult is the biochemical and physiological study of these products and their direct effects.The difficulties involved in such biochemical‐physiological studies is illustrated by a short discussion of the controversies around the possible role of plant lectins. While in Rhizobium the nod genes are present on a large sym‐plasmid, other essential genes must be present on the bacterial chromosome and on other plasmids. Induction of plant genes is evident from the formation of nodule‐specific proteins, the nodulins. Though many different plant and bacterial genes are involved in the series of steps in the development of an effective root nodule, there are indications that regulation is affected by a smaller number of essential regulatory genes. This is illustrated by the effect of the regulatory nod D gene during infection and nodulation, and of ntrA and nifA genes for the formation and activation of the nitrogen‐fixing systems. Moreover, every step, once initiated, may lead to cascade effects on subsequent reactions.Finally, some further consequences of the endophytic way of life are discussed, which affect either the metabolic and transport activities of the endophytes or their viability. This is illustrated by the possible role of membrane integrity as evident during the isolation of Frankia from its endophytic form.
Internode length in Pisum. Comparison of genotypes in the light and dark
Authors: Reid James B. 
Published: May 2006

There is a strong relationship across the full range of gibberellin deficient, internode length genotypes (le, lh, is, na) between internode length in the dark and in red or white light. Further, the new, more severe allele at the le locus. Ied, is shown to influence growth in the dark as well as in the light. These results suggest that darkeness does not specifically overcome any of the steps blocked by the gibberellin (GA) synthesis genes contrasting with the conclusions drawn by other workers. Supporting this conclusion in relation to the Ie gene are results which show that, at least at certain dosage rates, dark‐grown Ie na plants respond better to GA1 than to GA20 similar to the response previously reported in light grown plants.The greater response by plants of the nana line NGB1766 (na) to GA1 in the dark than in the light suggests that light may influence internode length by altering GA‐sensitivity. These results are discussed in relation to previous views on the control of stem elongation by light.
Effects of elevated oxygen tensions on acetylene reduction inAlnus incana‐Frankiasymbioses
Authors: Rosendahl Lis , Huss‐Danell Kerstin 
Published: May 2006

An open flow‐through gas system was used to determine the effect of C2H2and elevated O2on acetylene reduction activity (ARA) and respiration of the intact, potted root system ofAlnus incana(L.) Moench in symbiosis withFrankiaAvcll or with a local source ofFrankia. Both symbiotic systems responded to C2H2by an immediate plateau range in ARA. The Plateau in ARA was in some cases followed by a decline of less extent than reported for many legumes. A concurrent decline in net respiration of the root system was on average 8% of the CO2efflux prior to C2H2introduction.Respiration of the root systems in both symbioses responded to elevated oxygen levels in the 10 kPa C2H2atmosphere by an increase of up to 17% of the net respiration prior to C2H2introduction in 21 kPa O2. In contrast, the elevated oxygen levels resulted in an immediate drop in ARA followed by a minor increase to a stable level lower than that at the preceding, lower oxygen tension. The symbiosis with the localFrankiahad lost all ARA when the partial pressure of O2exceeded 50 kPa, whereas the symbiosis with Avcll still had some activity at 80 kPa O2. This difference in tolerance of elevated O2clearly shows that the oxygen exclusion mechanisms may be controlled by the microsymbiont inAlnus‐Frankiasymbioses. The symbiotic systems recovered ARA to a similar extent when returned from elevated O2levels to 21 kPa O2.
C and N utilization of two lettuce genotypes during growth under non‐varying light conditions and after changing the light intensity
Authors: Blom‐Zandstra Margaretha , Lampe Jan E. M. , Ammerlaan Fracina H. M. 
Published: May 2006

Growth and N‐incorporation in two lettuce genotypes (Lactuca sativa L. cv. Deci minor and cv. Grosse brune), which differ significantly in nitrate accumulation, were studied. Under constant environmental conditions cv. Deci minor produced more fresh and dry weight than cv. Grosse brune. Cultivar Deci minor also produced more fresh weight per mmol N absorbed than cv. Grosse brune, and contained less organic nitrogen in the dry matter, but accumulated more nitrate. As cv. Deci minor showed a higher fresh and dry weight production per mmol N absorbed than cv. Grosse brune, it used its nitrogen more efficiently.When the light intensity was decreased, the growth of both cultivars decreased, and the fresh weight production per mmol N absorbed increased. After reduction of the light intensity, cv. Deci minor maintained a higher fresh weight production per N absorbed than before, whereas cv. Grosse brune returned to its original level. After decrease of the light intensity, an increased nitrate concentration in the cell sap was accompanied by a decreased concentration of organic compounds in both cultivars. The organic nitrogen level in the dry matter remained constant after the higher intensity was reduced. However, due to the decreased dry weight percentage, the demand for nitrogen for protein synthesis decreased on fresh weight basis.It can be concluded that the two cultivars differ in their partition of C and N between dry matter and cell sap. Nitrate accumulation in preference to accumulation of organic compounds does not automatically result from a shortage of organic compounds. The high accumulation of nitrate of cv. Deci minor enables it to use more carbohydrates for structural growth than cv. Grosse brune.