bluuebunny/crossref_metadata_2025 huggingface dataset:
Étude de la discrimination strontium‐calcium chez le Haricot en fonction du rapport et des teneurs respectives en Sr et Ca de la solution nutritive
Authors: MYTTENAERE C. , MASSET M.
Published: April 2006

The discrimination between strontium and calcium is not only conditioned by the Sr/Ca ratio of the nutrient solution but also by the total dose (Ca + Sr) of the medium. The variation of the observed ratio in relation to the total dose is closely related with the Sr/Ca ratio of the solution. Sr is preferentially fixed by the roots when the Sr/Ca ratio of the solution is low; such a result is observed in the shoots for higher ratios. For all the treatments, the OR of the leaves is lower than unity (discrimination against strontium). When the stable strontium concentration of the solution is not detectable, an increase in the calcium concentration reduces the radiostrontium retention by the roots.
Methoxyhydroquinone, a Growth Inhibitor of Ophiobolus graminis, in Leaves of Oat Seedlings
Authors: OLSEN ROLF A.
Published: April 2006

A methanol extract of leaves of oat seedlings grown in sand cultures in the dark contained a compound which inhibited the growth of Ophiobolus graminis. The inhibitory factor was isolated and proved to be present in the plant as methoxyhydroquinone glucoside. The glucoside was readily hydrolysed to the corresponding aglucone. The methoxyhydroquinone, or possibly its oxydation product, methoxy‐P‐benzoquinone, was inhibitory to both Ophiobolus graminis var. graminis and Ophiobolus graminis var. avenae, whereas Fusarmm oxysporum var. lycopcrsici was not affected. Synthetic methoxyhydroquinone at 80 mg/l gave a 100% inhibition of Ophiobolus graminis var. graminis. After being exposed to 80 mg/l of the inhibitor for 24 h the mycelium was unable to initiate growth when transferred to a fresh nutrient solution. Only extracts from young leaves showed inhibitory activity, extracts from mature leaves giving no inhibition. The hydroquinone, or its glucoside, was not detected in roots of young seedlings, where avenacin was the only antifungal compound present.
The Mechanism of Apical Dominance in Coleus
Authors: THIMANN K. V. , SACHS TSVI , MATHUR K. N.
Published: April 2006

The development of lateral buds in isolated stems of Coleus blumei is inhibited by low concentrations of indoleacetic acid or other auxins, just as in other plants. The inhibition can be fully reversed by kinetin, about 3 times as much kinetin as IAA being needed. However, the outgrowth of the same lateral buds on intact Coleus plants is sensitive to environmental conditions, well‐nourished plants in full daylight often showing little inhibition by applied auxin. It is shown that (a) the solvent used for IAA, (b) the light intensity and (c) the nitrogen and phosphorus nutrition, all control the sensitivity of the buds to auxin inhibition. Using water instead of lanolin, lowering the light intensity or decreasing the supply of either nitrogen or phosphorus all increase the degree of apical dominance.
The Influence of Salinity and Temperature on Seed Germination in Salicornia bigelovii
Authors: RIVERS W. G. , WEBER D. J.
Published: April 2006

Seeds of Salicornia bigelovii were germinated at 4.4°C, 15.5°C, and 26.6°C in saline solution containing from 0% to 8.08% sea salt. At 4.4°C, germination was delayed until the 26th day, but the final germination per cent was high in all salinities. At 15.5°C, germination was delayed until the 19th day, and the germination per cent was higher in the higher salinities. At 26.6°C, the germination began within one day and the germination per cent was higher at the lower salinities. With the exception of 26.6°C data, the maximum germination occurred at a sea salt concentration at 4.04 % which is very close to the salinity of the sea.
Gibberellin‐like Substances in Developing Watermelon Seeds
Authors: BHALLA PRITHVI R.
Published: April 2006

Watermelon seeds were analyzed 4, 7, 9, 11, 19, 25 and 35 days after pollination. The gibberellin‐like substances were low up to 7 days after pollination, but increased rapidly in the next two days attaining a peak on the 9th day after pollination. The amount then declined and remained low till the seeds matured. Since the peak of gibberellin‐like activity coincided with (but did not precede) the time when the seeds attained their maximum size, it was concluded that it could not account for their growth. Instead, evidence was obtained to show that the peak may be correlated with the growth of the embryo and endosperm. Thin‐layer chromatography revealed the presence of three active gibberellin‐like factors at the 9th day after pollination. The chromatographic behavior of two of these active factors are similar to gibberellins A1 and A3. The data currently available are insufficient regarding the identification of a third gibberellin from watermelon seeds.
Growth‐Factors and Nucleic Acid Synthesis in Helianthus tuberosus
Authors: BAGNI N. , CORSINI E. , FRACASSINI D. SERAFINI
Published: April 2006

The study of the physiological significance of polyamines in higher plants has induced us to examine both the relationship between these compounds with indol‐3yl‐acetic acid (IAA) and the site of action of polyamines in the cell.

Slices of dormant tubers of Helianthus tuberosus were activated with water, 2 × 10‐6M IAA, 10‐4M spermidine and two different concentrations of actinomycin D alone and with spermidine.

The RNA synthesis caused by spermidine was similar to that caused by IAA. These data agreed with the hypothesis that the nucleic acid synthesis caused by IAA could be mediated by polyamine synthesis previously observed.

Besides 10‐4M spermidine removed the inhibition of 1.5 × 10‐6M actinomycin D on nucleic acid synthesis. As the interaction necessarily occurs between spermidine and actinomycin at the DNA level, it therefore was possible to demonstrate that the primary site of action of spermidine in protein synthesis might occur on DNA also in vivo.
Nitrogen and Carbohydrate Metabolism of Japanese Mint as Affected by Phosphorus Deficiency and Seasonal Variations
Authors: SINGH D. P. , SINGH J. N.
Published: April 2006

The paper presents effects of phosphorus deficiency and seasonal variations on nitrogen and carbohydrate metabolism of Japanese mint (Mentha arvensis L. var. piperascens, Holmes). Mint plants were grown in sand cultures under full nutrition and under phosphorus deficiency conditions during winter and summer. Various nitrogen and sugar fractions were determined in the component parts at specified periods of growth stages. Phosphorus deficiency disturbed the nitrogen metabolism at the stages for amide and amino acid formation, which resulted in an accumulation of carbohydrates. The content of total soluble and total nitrogen was higher and that of insoluble nitrogen was lower in summer as compared with winter plants. Of the soluble fractions, the ammonia, amide and nitrate nitrogen were higher and the ‘rest’ nitrogen lower in winter plants. Nitrate formed the highest bulk of the pool of soluble nitrogen in winter, whereas in summer ‘rest’ nitrogen was most abundant. The content of total sugar in winter plants far exceeded that of summer plants, which was wholly due to increase in sucrose content. Glucose was the predominant reducing sugar in both seasons. However, the summer plants were richer in glucose than those from the winter.
Transpiration in Three Eucalyptus Species as a Function of Solar Energy, Soil Moisture and Leaf Area
Authors: GINDEL I.
Published: April 2006

Three Eucalyptus species indigenous to Australia and successfully acclimatised in the subtropical and northern desert regions of Israel have been grown in pots. Two of them, which contained loess‐like desert soil, and one, which contained sandy soil, out of doors, have been exposed to extreme semi‐arid climatic conditions with only soil moisture under control. In each species one group has been kept at 15.5% and a second at 7% moisture. The groups grown in water deficient soil had a 31.0–42.8% smaller leaf area and a 2–4 fold lower transpiration rate, the values varying with species. When soil moisture was raised to the same level for the water deficient groups and the plants grown at field capacity an equal or a higher transpiration rate was obtained. This happened although both groups had been exposed to the same intensity of solar radiation and in spite of the significantly smaller leaf area in the groups grown in water deficient soil. In woody xerophytes grown in water deficient soil under arid conditions, the quantity of available soil moisture and the inherent biological properties of the species decide the rate of transpiration and not the area of the foliage or the intensity of solar radiation, or physical evaporation.
Role of Ascorbic Acid in Bud Development
Authors: JOHNNYKUTTY A. T. , KHUDAIRI A. K.
Published: April 2006

Ascorbic acid was found to increase bud development in Pisum sativum L. The interactions of ascorbic acid with indole‐3‐acetic acid, kinetin and gibberellic acid were studied. It was found that ascorbic acid promoted bud growth and overcame the inhibitory effect of auxin. When applied with gibberellin, bud growth was greatly enhanced. Ascorbic acid promoted bud development in red light only; it did not in far‐red or dark.
Influence of Age and Light on the Distribution and Development of Nitrate Reductase in Greening Barley Leaves
Authors: JORDAN W. R. , HUFFAKER R. C.
Published: April 2006

The relation between leaf age and the induction of nitrate reductase activity by continuous and intermittent light was studied with barley seedlings (Hordeum vulgare L. cv. Club Mariout). In general, nitrate reductase activity declined as the period of growth in darkness was extended beyond 5 days. Maximum activity was found near the leaf tip while activity was lowest in the morphologically youngest tissue near the base of the lamina. Increased activity was observed after continuous illumination of dark‐grown seedlings for 24 hours. The increase in activity in response to light was greatly reduced when the dark pretreatment period was extended beyond 8 days. The amount of nitrate reductase activity present in the different sections of the leaf was closely related to the amount of polyribosomes present. The pattern of chlorophyll accumulation closely parallelled that of increases in nitrate reductase activity.

The initial lag in the induction of nitrate reductase activity was removed by a 10‐minute light treatment 6 hours before placing dark‐grown barley seedlings in light. The enzyme was also induced under flashing light with various dark intervals. These induction curves closely resembled those of chlorophyll accumulation under the same conditions.

The development of photosynthetic CO2 fixation follows the same induction pattern in this system. Our results suggest that photosynthetic products may be required for the induction of significant levels of nitrate reductase activity in leaves of dark‐grown seedlings, although other light effects may not be discounted.
The Nature of Root‐Promoting Substances in Lycopersicon esculentum Seedlings
Authors: AUNG L. H.
Published: April 2006

Determination of the organ sites and chemical nature of root‐promoting substances in Lycopersicon esculentum seedlings was made. Results of organ excision indicated that the young cotyledons were the primary site of root‐promoting substances. As the cotyledon matured, its root‐promoting activity decreased while that of the developing plumular leaves increased. Application of 2,3,5‐triiodobenzoic acid (TIBA) at 10−3 M in lanolin to the hypocotyl below the cotyledonary node significantly prevented root formation. Bioassay, using a new tomato rooting test, of the basic, acidic and bound fractions of the cotyledon extracts after paper chromatography showed biological activities in all three fractions. Gas‐liquid chromatography of selected active regions of the paper chromatogram resulted in a partial tentative identification of indolepropionic acid, 5‐methylindole, 5‐hydroxy‐indole and 3‐indoleacetonitrile. The combined evidence indicated that the root‐promoting substances in tomato seedlings resemble auxin compounds.
Effects of Selected Herbicides on Plant Protoplasts
Authors: BOULWARE MARGARET A. , CAMPER N. DWIGHT
Published: April 2006

Plant protoplasts were released from immature tomato fruits by incubation with a 20% solution of polygalacturonase (Pectinol R‐10, Rhom & Haas) dissolved in 0.1 M KCl + 0.1 M MgCl2. In this salt solution the protoplasts remained stabilized for up to 8 h and were used as a source of exposed plasma membrane. Gross responses of protoplasts to selected chemicals and herbicides were recorded photomicroscopically.

Paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) treatments resulted in a characteristic response which was different from that of general denaturants (trichloroacetic acid, ethanol, and detergents) and of osmotic shock. Initial phases of the paraquat response were characterized by a segregation of the cytoplasm into isolated areas on the inner membrane surface. The final phase was a rupture of the plasma membrane and collapse of the cell.

The herbicides, 2,4′‐dinitro‐4‐trifluoromethyl‐diphenylether (preforan); 1,1‐dimethyl‐3‐(α,α,α‐trifluoro‐m‐tolyl)urea (fluometuron); 3‐(3‐chloro‐4‐bromophenyl)‐1‐methoxy‐1‐methylurea (chlorbromuron); and α,α,α‐trifluoro‐2,6‐dinitro‐N‐N‐dipropyl‐p‐toluidine (trifluralin) produced no apparent structural effect on the protoplasts.
Effects of Abscisic Acid and its Esters on Stomatal Aperture and the Transpiration Ratio
Authors: JONES RUTH J. , MANSFIELD T. A.
Published: April 2006

A single surface application of abscisic acid or its methyl and phenyl esters suppressed stomatal opening on leaves of Xanthium strumarium. The effect was restricted to the treated parts of the leaf blades, there being no detectable translocation to untreated parts. There were no increases in CO2 compensation to which stomatal closure could be attributed.

Abscisic acid and its esters acted successfully as antitranspirants when applied once to leaf surfaces of young barley plants. Over a 9‐day period there was a reduction of about 50% in the amount of water transpired without any detectable reduction in the rate of dry weight increase. The treatments reduced transpiration relatively more than dry matter accumulation, and hence there was an increase in the water use efficiency. The effect of the treatments became progressively less over 9 days, but even at the end of the experiment (day 9) both the esters reduced transpiration by 20–25%. The esters were slightly more effective than abscisic acid itself.

On the basis of the data presented here, field trials of the antitranspirant properties of these compounds are recommended.
The Selective Effect of Abscisic Acid on Ribonucleic Acid Components
Authors: LESHEM Y. , SCHWARZ LEAH
Published: April 2006

As determined by methylated albumin kieselguhr (MAK) fractionation, GA3 (gibberellic acid) significantly increased and ABA (abscisic acid) decreased RNA levels. In the case of ABA this effect was selective, the ribosomal RNA manifesting the typical decrease; while the sRNA peak was markedly increased. The pattern of labelled uridine incorporation into RNA resembles the MAK absorbancy profile and here as well, ABA although causing an overall decrease, increases labelling in the sRNA peak. The results are interpreted as a possible selective effect of ABA or alternatively as an accumulation in the sRNA peak of rRNA breakdown products. From in vitro experiments it was furthermore evident that ABA mediated RNA hydrolysis probably does not involve a direct activation of RNase by ABA. The in vivo effect would probably be devious.
Aphanizomenon flos‐aquae: Infection by Cyanophages
Authors: GRANHALL ULF
Published: April 2006

This report presents electron microscopic observations of a virus infection of Aphanizomenon flos‐aquae (L.) Ralfs and investigations on the presence of the causative cyanophage in a moderately eutrophic lake. The results indicate that the cyanophages regulate termination of the water‐bloom of this alga.
Growth of Variants of Myxococcus virescens
Authors: STÄHL STEN
Published: April 2006

Some observations on variant strains of Myxococcus virescens B2 with special emphasis on characteristics associated with the ability to grow in dispersion are reported. The isolated strains were divided into two major classes according to their mode of growth in shaken and static liquid cultures based on casitone and casamino acids media. Strains growing in dispersion were designated D+‐strains and those growing in aggregates or as films, D−‐strains.

Colony morphology, cell morphology, growth in liquid and on solid medium and morphogenesis were compared. The ability to grow in dispersion shown by D+‐strains seemed to be associated with a smooth colony on casitone agar, inability to form typical fruiting bodies and a low linear growth rate of colonies on solid medium as compared with the D−‐strains. In contrast D−‐strains produced rough colonies on casitone agar, were able to fruit and evidently formed an adhesive slime in the form of fibrils extending from the cell surface.

It is suggested that the observed differences depend on different envelopes of the cells in the two classes.
Properties of the Invertases of Cultured Sycamore Cells and Changes in Their Activity during Culture Growth
Authors: COPPING LEONARD G. , STREET H. E.
Published: April 2006

When cultured sycamore cells are homogenised in a phosphate‐citrate buffer at pH 7.0 and the homogenate centrifuged two fractions are obtained both of which show the presence of an acid (opt. pH 4.0–4.5) and a neutral (opt. pH 7.0–7.4) invertase. The activity of the insoluble pellet appears to be located in its cell wall fragments. The acid and neutral invertases of the soluble fraction can be separated by fractional precipitation with (NH4SO4.

The activities of these enzymes are low in stationary phase cells but they increase following subculture to reach peaks of activity towards the end of the period of most active cell growth and division and then decline again as the cells begin to enter stationary phase. The activities of both enzymes are higher in the cell wall than in the soluble fraction and the acid invertase reaches higher levels of activity than the neutral enzyme in both fractions.

When cells are subcultured there occurs within a few hours an increase in the acid invertase and a decline in the neutral invertase activity in the cell wall fraction and a decline in the acid invertase of the soluble fraction prior to the large net increases in the activities of both enzymes in both locations which occurs as the cells embark upon cell division.

The pattern of changes in the invertase activities through the growth cycle of batch propagated cultures is similar whether the cells are grown in sucrose, or glucose, or sucrose plus glucose; the highest levels of activities were recorded in the glucose‐grown cells.

The total yield of invertase activities and the distribution of activities between the soluble and cell wall fractions of the homogenates are affected by the pH of the extraction medium (within the range pH 4.0–8.0). It has not proved possible to completely remove the invertases from the cell wall fraction; upwards of 50 % of the acid invertase was recovered from this fraction by treatment with Triton‐X followed by urea, but these treatments inactivated a high proportion of the neutral enzyme.

These findings are compared with other studies on the activity and intra‐cellular distribution of plant invertases and the possible roles of these enzymes discussed.
Wall‐bound Invertase Activity in Convolvulus Callus: Increase after Subculturing, and Paradoxical Effects of Actinomycin D, Cycloheximide, and Thienylalanine
Authors: KLIS F. M. , HAK A.
Published: April 2006

The wall‐bound invertase activity increased 3.3‐fold upon transfer of fragments of Convolvulus callus to fresh solid nutrient medium and 7.7‐fold upon transfer to liquid nutrient medium. Addition of actinomycin D, cycloheximide or the amino acid analogue thienylalanine brought about a further stimulation of the invertase content of the cell walls. The rise of wall‐bound invertase activity was not due to redistribution of invertase activity between cytoplasm and cell walls, and appeared to be dependent on metabolic energy.

An equation is presented to calculate the half‐life of enzymes from their time‐course. Applied on the time‐courses of wall‐bound invertase activity, a half‐life of about 12 h was obtained in callus transferred to fresh solid medium and of about 5.4 h in tissue transferred to liquid medium. It is argued that the increase of invertase content of the cell walls is due to an enhanced rate of invertase synthesis.
Adaptive Biosynthesis of Thiazole and Bypassing of the Thiazole Requirement in Exobasidium by Acetyl Phosphate, Tween and Ethanol
Authors: SUNDSTRÖM KARL‐RAGNAR
Published: April 2006

The tested strain of Exobasidium vaccinii (Fuck.) Woron. required thiamine or its two moieties, thiazole and pyrimidine, for good growth. When grown on pyrimidine medium, rapid growth or thiazole synthesis appears after 600–1000 hours. As methionine, a supposed precursor in the biosynthesis of thiazole, stimulates this inductive growth, the influence of methionine precursors or metabolites stimulating methionine synthesis were tested for their ability to shorten the lag phase of E. vaccinii cultured on a thiamine‐deficient synthetic medium. None of the tested methionine precursors replaced methionine or significantly stimulated the inductive growth. This result does not exclude acetylhomoserine as a central metabolite in methionine synthesis.

Acetyl phosphate, alcohols and the fatty acids of Tween, possible deliverers of the active acetyl groups, induced growth in thiamine‐free media. This growth seems to be possible by utilization of the compounds through a metabolic pathway not requiring thiamine. No evidence for participation of the glyoxylate cycle was found.
Rhizomorph Formation in Fungi I. Stimulation by Ethanol and Acetate and Inhibition by Disul‐firam of Growth and Rhizomorph Formation in Armillaria mellea
Authors: SORTKJÆR O. , ALLERMANN K.
Published: April 2006

Rhizomorph formation in Armillaria mellea (Vahl ex Fr.) Quél. has been studied on a synthetic glucose medium with ethanol and acetate as inducers. Disulfiram (antabuse) inhibited growth and rhizomorph formation when ethanol was the inducer, while the stimulating effect of acetate was unaffected. This indicates that ethanol is metabolised by the normal pathway via acetate.

Growth, ethanol‐ and glucose uptake were measured as a function of time. Ethanol was used up in 12 days; after that, growth and glucose uptake declined. A further supply of ethanol gave a significant increase in the growth rate. The results show that ethanol is a limiting growth factor during the entire growth period.
Correlative Changes in Phytohormones in Relation to Senescence Processes in Rose Petals
Authors: MAYAK S. , HALEVY A. H. , KATZ M.
Published: April 2006

A comparative study of the level of abscisic acid (ABA) and cytokinin and of ethylene production by rose (Rosa sp.) petals of the short‐lived cultivar Golden Wave (Dr. Verhage) and the long‐lived cultivar Lovita was conducted. In both cultivars, the level of ABA increased as the flowers aged; it was higher in Golden Wave in all developmental stages tested.

Ethylene production by cut flowers of the two cuitivars remained low for a short time concomitant with development and then increased sharply. The rise in ethylene production occurred after 3 and 4 days in Golden Wave and Lovita, respectively. Cytokinin level increased as the flower started to open and then decreased to a low level. The significance of these changes in relation to maturation and senescence of rose petals is discussed.
The Effect of Light on Tobacco Mosaic Virus (TMV) Formation
Authors: OLSSON R.
Published: April 2006

Discs were punched from TMV‐inoculated tobacco leaves (Nicotiana tabacumL.) and illuminated while floating on half strength Vickery's solution maintained at 24°C. After 48 hours some discs were placed in the dark for 24 hours and the amount of TMV formed in the light and dark compared. Discs from young leaves formed more virus in the light than in the dark. Discs from older leaves produced less virus, but as much in the dark as in the light.
Effects of Ammonium and Potassium Ions on Some Physiological and Biochemical Processes of Excised Cucumber Cotyledons
Authors: PATNAIK RABINDRANATH , BARKER ALLEN V. , MAYNARD DONALD N.
Published: April 2006

Incubation of excised cucumber cotyledons (Cucumis sativus L.) with NH4Cl solutions exceeding 0.001 M inhibited their greening, fresh weight increases, and incorporation of 14C‐leucine into insoluble N compounds. The absorption of 14C‐leucine during incubation and retention of moisture by the excised cotyledons after incubation were greatly diminished by the NH4Cl treatments. Treatment with KCl solutions of the same concentrations as the NH4Cl stimulated the greening, fresh weight increases, and the absorption and incorporation of 14C‐leucine. Desiccation of cotyledons stored at 5°C for 10 days was inhibited by dilute KCl solutions. The toxicity of NH4Cl was alleviated by KCl solutions at low concentrations.
Gibberellins in Diffusates from Shoots of Apple Trees
Authors: GRAUSLUND JØRGEN
Published: April 2006

Excised shoot apices, leaves and internodes from shoots of apple trees (Malus×domestica) give off gibberellins by diffusion on agar. A methanol extract of the agar was prepared, the extract separated on thin layer plates, and the gibberellin activity estimated by means of Rumex and lettuce hypocotyl bioassays. The largest amounts of gibberellin are found in diffusates from the shoot apex, the two upper leaves and the two upper internodes. Several promotive fractions are found on the chromatograms as well as growth inhibitors.

Removal of young leaves retards elongation of the internodes. Probably gibberellins produced in young leaves exercise some control over this process.

The growth regulators Alar and CCC also retard internode elongation. Diffusates from shoots treated with these substances were also examined. Preliminary results suggest that the amount of diffusible gibberellins from treated shoots is not reduced.
The Influence of Urea and Other Nitrogen Sources on Growth Rate of Scots Pine Seedlings
Authors: CHRISTERSSON LARS
Published: April 2006

The growth rate and water content of urea‐fed seedlings of Pinus silvestris L. were compared with those of nitrate‐and ammonium‐fed seedlings grown in continuously renewed nutrient solutions, in which the hydrolysis of urea to ammonia and carbon dioxide was minimized. The growth rate of seedlings grown in an ammonium nutrient solution, in an urea nutrient solution and in a nitrate nutrient solution was about 90 per cent, 75 per cent and 60 per cent, respectively, of that of seedlings grown in a mixture of ammonium and nitrate. Seedlings with urea as the sole nitrogen source developed very severe chlorosis of the needles, the old roots were dark‐coloured, the whole root system was very fragile, and the lateral roots of the third order were missing. Urea‐grown seedlings had the highest nitrogen contents, closely followed by the ammonium and the ammonium + nitrate seedlings. The lowest nitrogen level was in nitrate seedlings. The low growth rate and the chlorosis of urea‐fed seedlings were suggested to be the result of a hydrolysis of urea inside the root, causing an increase in pH and an accumulation of ammonia in the root.
Inducible Formation of Glutamate Dehydrogenase in Rice Plant Roots by the Addition of Ammonia to the Media
Authors: KANAMORI TETSUO , KONISHI SHIGEKI , TAKAHASHI EIICHI
Published: April 2006

The activity of glutamate dehydrogenase (l‐glutamate: NAD oxidoreductase, EC 1.4.1.2.; GDH) of rice plants changes in response to the nitrogen source supplied to the culture solution. The activity of NADH‐GDH(aminating) in roots is rapidly increased by the addition of ammonia, whereas the activity in shoots is much less affected by nitrogen supply. The activity increased with increasing concentration of ammonia at least up to 14.3 mM. In roots GDH activity was found in both the mitochondrial and soluble fractions. The increase of NADH‐GDH activity caused by the ammonia treatment occurs mainly in the latter fraction. The new band with GDH activity was detected on the zymogram of polyacrylamide gel electrophoresis and this inducible enzyme is active with both NAD and NADP. On the other hand, the constitutive enzyme activity active with NAD is also increased by the ammonia treatment. The increase of enzyme activity is prevented by the addition of cycloheximide or chloramphenicol to culture medium. The incorporation of 14C‐leucine(U) into GDH proteins was also studied using polyacrylamide gel electrophoresis. Higher radioactivity was found in induced samples than in non‐induced ones. These results show that the increase of GDH activity in roots by ammonia treatment seems to depend on de novo protein synthesis.
Translocation and Persistence of 1,2‐14C‐(2‐Chloroethyl)‐phosphonic Acid (Ethephon) in Thompson Seedless Grapes
Authors: WEAVER ROBERT J. , ABDEL‐GAWAD HESHAM A. , MARTIN GEORGE C.
Published: April 2006

Applications of 1,2−14C‐(2‐chloroethyl)phosphonic acid (ethephon) were made to the surface of mature Vitis vinifera cv. Thompson Seedless berries. After 7 days, 62 % of the recovered radioactivity was still on the outside surface and was easily washed off. Within the berry, radioactivity was present only in the carbon‐labeled ethephon fraction, as revealed by chromatographic analysis. Similar results were obtained when the compound was injected directly into the berries. Application of ethephon to the first leaf above the cluster, or to a berry pedicel or a peduncle, failed to result in measurable movement of the compound into the berries. Autoradiographic studies with young shoots indicated that ethephon translocated in the phloem in a source to sink relationship.
Control of the Biosynthesis of Phenylalanine and Tyrosine in Plant Tissue Cultures: Lack of Repression of Chorismate Mutase
Authors: CHU MARGARET , WIDHOLM J. M.
Published: April 2006

Tobacco, rice, carrot and tomato tissue cultures were grown in liquid media containing l‐phenylalanine or l‐tyrosine, or both together. The addition of these amino acids increased their respective cellular levels (4–20 fold), but did not lower the level of chorismate mutase, an enzyme in the biosynthetic pathway of phenylalanine and tyrosine. These results indicate that the biosynthesis of phenylalanine and tyrosine in cultured plant cells is not regulated by repression of the synthesis of chorismate mutase by phenylalanine or tyrosine.
Deoxyribonucleotide Pools in Plant Tissue Cultures
Authors: NYGAARD PER
Published: April 2006

Two dimensional thin‐layer chromatography on anion‐exchange cellulose enables the separation of the normally occurring ribo‐ and deoxyribonucleoside triphosphates. This technique was applied to perchloric acid extracts of callus tissue of sycamore and tobacco and of pine pollen grown in 32P‐orthophosphate labelled media to quantitate the nucleoside triphosphate pools under different growth conditions.

The results showed that the ratio of the deoxyribonucleo‐side triphosphates to their corresponding ribonucleoside triphosphates is low in plant cells, similar to the ratio previously found for animal cells.

During the period of most rapid DNA synthesis in the callus tissue, the deoxyribonucleoside triphosphate pools reach their highest values. This effect is also demonstrated with cells of Escbericbia coli.
Malate Dehydrogenase Isoenzymes in Cotton Leaves of Different Ages
Authors: O'SULLIVAN STEPHEN A. , WEDDING RANDOLPH T.
Published: April 2006

Malate dehydrogenase isoenzymes from the blades of different aged leaves of the cotton plant have been investigated. The total extractable malate dehydrogenase activity varied widely between leaves of different ages and different locations on the plant. Malate dehydrogenase zymograms developed from the extracts which contained significantly different levels of enzyme activity appear to indicate the presence of different groups of malate dehydrogenase isoenzymes in leaves of different ages. However, under appropriate conditions of polyacrylamide gel electrophoresis, the same number of malate dehydrogenase isoenzymes with the same relative mobilities were detected in all the leaves studied.

These findings are discussed in relation to reports that malate dehydrogenase isoenzymes change with plant development or that they have different roles in the plant.
Callus and Cell Suspension Cultures of Carnation
Authors: ENGVILD K. C.
Published: April 2006

Callus cultures of carnation, Dianthus caryophyllus L. ev. G. J. Sim, were grown on a synthetic medium of half strength Murashige and Skoog salts, 3 % sucrose, 100 mg/l of myo‐inositol, 0.5 mg/l each of thiamin, HCl, pyridoxin, HCl and nicotinic acid and 10 g/l agar. Optimal concentrations of growth regulators were observed to be 3 × 10−6M indoleacetic acid (JAA) combined with 3 × 10−6M benzylaminopurin (BAP) or 10−6M 2,4‐dichlorophenoxy acetic acid (2,4‐D) alone. IAA + BAP caused a 100 fold increase in fresh weight over 4 weeks at 25°C. Addition of casein hydrolysate increased growth further.

Cell suspension cultures worked best in media containing 2,4‐D in which they had a doubling time of about 2 days. Filtered suspensions were successfully plated on agar in petri dishes, but division was never observed in single cells. The cultures initiated roots at higher concentrations of IAA or NAA, but all attempts to induce formation of shoots or em‐bryoids gave negative results.
Evidence for the Activation of NADH‐cytochrome c Reductase during Germination of Lettuce
Authors: ELDAN M. , MAYER A. M.
Published: April 2006

A very rapid increase in particulate cytochrome c reductase activity during the very early stages of germination of lettuce is demonstrated. The increase in activity does not parallel water uptake or the increase in cytochrome oxidase activity. The increase is reversible on drying of imbibed seeds and is not inhibited by cyanide. It is concluded that the increase in activity is due to some kind of activation process and not to de novo synthesis of protein. Possible mechanisms of activation were investigated. It was not possible to simulate the activation process in vitro, in the isolated particulate fraction.
Physiological Studies on Pea Tendrils VIII. The Relationship of Circumnutation to Contact Coiling. — With a Description of a Laboratory Intervalometer Using Integrated Digital Circuits
Authors: JAFFE M. J.
Published: April 2006

The average rate of rotation of circumnutating tendrils of Pisum sativum L. ev. Alaska, was 1.57 ± 0.29 mm/min. 53% of the tendrils rotated clockwise and 47% counterclockwise. Circumnutation is apparently dependent on the maintenance of sufficient turgor as it stopped when either the roots or all the shoot appendages except the terminal tendril were excised, but resumed when the aerial wounds were covered with petroleum jelly.

Both circumnutation and contact coiling were similarly retarded when the plant was cut in the middle of the top inter‐node, or by the use of either juvenile or senescent organs.

As the tendril circumnutated rapidly during the sweeping portion of its circuit, it was capable of coiling at only about 57% of the rate of which it could coil if stimulated during the relatively slow moving turn, Conversely, when the tendril was mechanically stimulated to coil, its rate of circumnutation decreased markedly and remained retarded as long as the tendril continued to coil.

On the basis of these observations, it is concluded that contact coiling does not seem to be simply a modified form of circumnutation, but the two modes of movement might be related through a negative feedback system.
Interaction of Kinetin and Abscisic Acid in the Avena Straight‐Growth Test
Authors: HEMBERG TORSTEN
Published: April 2006

Different amounts of abscisic acid, 2.7 × 10−9− 5 × 10−8 moles, were chromatographed in isopropanol: ammonia: water (100:14:6), firstly alone and secondly together with 5 × 10−8 moles kinetin. The same amount of kinetin was also chromatographed alone. The chromatograms were tested biologically with the Avena straight‐growth test. Whereas a large part of the chromatograms of kinetin gives growth stimulation, the Rf region 0.4–0.6 of abscisic acid chromatograms is strongly growth‐inhibiting. The inhibition within this Rf region does not become less if abscisic acid and kinetin are chromatographed together.
A Comparative Study of the Changes in Root Growth, Induced by Coumarin, Auxin, Ethylene, Kinetin and Gibberellic Acid
Authors: SVENSSON SVEN‐BÖRJE
Published: April 2006

The effect of coumarin, IAA, ethylene, kinetin and gibberellic acid on roots of maize and wheat was investigated. Sterile attached and detached roots and isolated elongation zones were used. In some experiments a semi‐sterile procedure was followed. The effects of the different regulators separately or in various combinations together with coumarin were studied on the root growth with regard to division, elongation and swelling of the cells. The ethylene production in isolated elongation zones was measured after treatment with coumarin, IAA, PCIB, kinetin, colchicine and dinitrophenol.

The results show the following: 1) Each substance produces a specific morphologic pattern. 2) Changes in polarity were demonstrated for auxin‐induced swelling in cell divisions and cell expansion and for coumarin‐induced swelling in cell divisions. Other cell expansion in swollen parts was due to cylindric cells increasing in width while retaining their cylindric form. 3) Coumarin‐induced inhibition could not be counteracted by IAA, PCIB, carbon dioxide, kinetin, gibberellic acid or Cycocel. 4) The ethylene production in isolated elongation zones increases noticeably after kinetin treatment, less strongly after auxin treatment and least after coumarin treatment. The production of ethylene does not seem to be correlated with the morphogenetic effect of the different substances. 5) The isolated elongation zones reacted to a) IAA and kinetin with an increase in length in some cases and b) gibberellic acid with a reduction of their width. 6) The inhibitory effect of coumarin on the growth in length of the elongation zones was diminished by kinetin. The swelling produced by coumarin in these zones was reduced by gibberellic acid. The effects just mentioned of kinetin and gibberellic acid were considered as indirect ones. ‐ From the present findings it was concluded that concomitant effects of auxin, ethylene, cytokinins and gibberellins are not obligatory for coumarin to exert its morphogenetic effects on root growth. In discussing the results some pitfalls in studies of growth reactions after application of hormones to roots containing meristem were emphasized.
The Influence of Atrazine, Benzyladenine, and the Embryonic Axis on Chlorophyll Synthesis in Cucumber and Squash Cotyledons
Authors: PENNER DONALD , WILEY LORRAINE
Published: April 2006

Excision of the embryonic axis prior to 3 1/2 days of germination in the dark followed by 8‐h of light decreased the total chlorophyll content of cucumber cotyledons but not squash cotyledons. Benzyladenine stimulated the accumulation of chlorophyll in the cotyledons of intact embryos and excised cotyledons in both cucumber and squash. Gibberellic acid had no effect. Atrazine inhibited chlorophyll formation in excised squash cotyledons. Benzyladenine also increased the carotenoid and xanthophyll content in the cotyledons from intact squash seedlings.

The results suggest that pigment synthesis in cotyledons may be controlled by a number of substances produced in the embryonic axis and that cytokinin‐like benzyladenine can simulate the action of one of them.
Effect of Several Transpiration Suppressants on Carbon Dioxide and Water Vapor Exchange of Citrus and Grapevine Leaves
Authors: BRAVDO BEN‐AMI
Published: April 2006

Several transpiration suppressants, (phenyl mercuric acetate, Tag 16 (polyethylen emulsion) R14‐poly (ethylene adipate) 4–4 Diphenylmethan diisocyanate), which are known to either close stomata or form thin films on leaves, were sprayed on citrus and grapevine seedlings. Water vapor and carbon dioxide exchange of single leaves were measured by means of infra red gas analyzer and L1C1 hygrosensors. The effects of the chemicals were evaluated by analyzing net photosynthesis, transpiration, mesophyll resistance to CO2 compensation concentration and respiration. All the chemicals tested increased either mesophyll resistance or CO2 compensation point to various degrees. It is concluded that none of the chemicals tested acted solely on epidermal resistance. All chemicals reduced photosynthesis, but the ratio of photosynthesis to transpiration increased in most cases in grapevine but not in citrus. Different chemicals acted differently on citrus and grapevine. The method of analysis used enabled us to evaluate separately the relative effect of a chemical on mesophyll resistance and respiration.
Influence of Nitrogen Supply on Uptake and Translocation of Strontium and Calcium in Wheat Seedlings
Authors: ANDERSEN A. J. , JACKSON W. A.
Published: April 2006

Supplying nitrate to N‐depleted wheat seedlings (Triticum vulgare cv. Knox) stimulated the uptake and translocation of both 83Sr and 45Ca. Since the increase in 45Ca accumulation was greater, the 85Sr/45Ca ratio in the plant tissue was decreased. Nitrate had relatively little influence on the amount of the divalent cations and 85Sr/45Ca ratio in the exchangeable fraction on the root surfaces, whereas it greatly increased the uptake into root tissue and translocation to shoots. The increase in percent transported to shoots occurred largely in the period of most rapid nitrate uptake.

A split root study indicated that nitrate was ineffective when it was supplied to a different portion of the root system than that exposed to 85Sr and 45Ca. Nevertheless, ammonium and urea also increased the translocation of the two cations, indicating that the effects of nitrate could not entirely be ascribed to a direct effect of the nitrate anion.
The Effect of NAA (1‐Naphthaleneacetic Acid) and Morphactin (Methyl 2‐Chloro‐9‐hydroxyfluorene‐9‐carboxylate) on RNA and Protein Synthesis in Senescing Bean Endocarp
Authors: SALMINEN SEPPO O. , GAGIANAS ATHAN A. , BERG ARTHUR R.
Published: April 2006

The effect of NAA (1‐naphthaleneacetic acid) and morphactin (methyl 2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate) on the uptake and incorporation of uridine‐5‐3H and l‐leucineU‐14C was studied in senescing bean endocarp (Phaseolus vulgaris L. cv. Kentucky wonder pole beans) sections. Both growth regulators inhibited uptake of these precursors and appeared to affect different components of the uptake mechanism. A possible synergistic inhibition was seen in case of leucine, but in case of uridine, the effect was less than additive.

A strong synergistic increase in the incorporation of l‐leucine into protein was seen. Thus, morphactin interacted with an exogenously applied auxin at the level of the protein synthesizing apparatus.
Temperature Response of Adenosine Triphosphatase of Bean Roots as Related to Growth Temperature and to Lipid Requirement of the Adenosine Triphosphatase
Authors: KUIPER P. J. C.
Published: April 2006

The ATPase activity of the cell wall, mitochondrial and microsomal fractions of bean roots (Phaseolus vulgaris) shows non‐linear curves when plotted logarithmically against temperature, producing high Q10‐values in the low temperature range and low Q10‐values in the high temperature range. The Q10‐valuc of supernatant ATPase is constant and low as well as the Q10‐value of soluble ATPase liberated from membranes. Cell wall ATPase from bean roots adapted to a low temperature has a much smaller temperature response. Such roots contain a larger quantity of membrane‐bound ATPase and a smaller amount of soluble ATPase than roots adapted to a high temperature.

Extraction of soluble ATPase with acetone reduces activity to practically zero, but activity could be partially restored by the addition of lipid. The temperature response of reconstituted phosphatidyl choline‐ATPase is inconsiderable. That of reconstituted sulfolipid‐ATPase is much larger.

I am indebted to Bep Stuiver for skillful assistance with the experiments, to Ir. F. Kuiper and Mr. C. H. Vermeulen for help with the cultivation of the bean plants and to Prof. Dr. E. C. Wassink for reading the manuscript.

Communication 292 of the Laboratory of Plant Physiological Research, Agricultural University, Wageningen, The Netherlands.
Effect of Light on the Response of Pea Seedling Roots to 2,4‐Dichlorophenoxyacetic Acid
Authors: ELIASSON LENNART , PALÉN KJELL
Published: April 2006

White light increases the inhibition of growth in length of pea seedling roots caused by 2,4‐D. This effect is most pronounced in the case of lateral root growth. The effect is obtained also if the shoots above the cotyledons are removed and is probably due to the direct influence of light on the roots. While light also weakly enhances the inhibition of pea root growth caused by 1‐naphthylacetic acid, light does not increase the sensitivity of wheat roots to 2,4‐D or naphthylacetic acid.
Effect of Gibberellic Acid on Dark and Light Germination at Different Temperatures of Calluna, Ledum andRhododendron Seeds
Authors: JUNTTILA OLAVI
Published: April 2006

The aim of the experiments was to study the effects of gibberellic acid (GAs) on the germination of Calluna vulgaris L., Ledum palustre L. and Rhododendron lapponicum (L.) Wahlenb. seeds under different environmental conditions.

Under continuous light from white fluorescense tubes (3000 lux), untreated seeds of Calluna were partly dormant at all temperatures studied (9, 15, 21, 27, 27/9, 8/16 hours). Percentage of dormant seeds increased, however, with decreasing temperature, and it varied also from seed lot to seed lot. Untreated seeds of Ledum were dormant in light at 9° and 15°C but not at higher temperatures. Untreated seeds of Rhododendron were completely dormant in light at temperatures from 13° to 24°C. Seeds of all species were completely dormant in darkness both at 15° and 27°C. GA3 stimulated greatly the germination of all species under all studied environmental conditions. The used concentrations (0.2–3.2 mM) gave nearly 100% germination in most cases. At 9°C the dormancy in some seed lots of Calluna and Ledum was only partly broken by the used concentrations of GA3.
Enhancement of Intact Bean Leaf Senescence by NaCl Salinity
Authors: PRISCO JOSE TARQUINIO , O'LEARY JAMES W.
Published: April 2006

Red kidney bean (Phaseolus vulgaris L.) plants were grown in nutrient solution and in nutrient solution plus four bars of added NaCl. Chlorophyll and protein decay occurred much more rapidly in intact leaves from plants subjected to four bars of added NaCl in the growth medium than in intact leaves from plants without added NaCl. Ribonucleic acid (RNA) content in intact leaves of salt treated plants was higher than in intact leaves from plants grown in nutrient solution alone. However, the tendency for RNA content variation in leaves during the experimental period was the same for both control and salt treated plants. The results support the idea that salinity enhances senescence and suggests that hormone imbalance plays an important role in this process.
Extracellular Lytic Enzymes of Myxococcus virescens
Authors: HASKÅ GUNO
Published: April 2006

Two bacteriolytic hexosaminidases isolated from Myxococcus virescens were characterized. When acting on purified cell walls of Micrococcus lysodeikticus they liberated reducing groups and N‐acetylhexosamines. By chromatography on Sephadex G‐50 and G‐25 columns disaccharides were isolated from degraded cell walls. After reduction of the disaccharides with sodium borohydride the acid hydrolysis products were identified by thin layer chromatography. Only pale spots of glucosamine appeared after this treatment but the spots of muramic acid remained unchanged. The enzymes were found to be devoid of exo‐β‐N‐acetylglucosaminidase activity. These results are compatible with the action of endo‐β‐N‐acetylglucosaminidases.