bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Fluorescent Brighteners to Visualise the Sites of Cellulose Synthesis in the Root Hairs of Species of Peperomia
Authors: TAMPION J. , McKENDRICK M. E. , HOLT G.
Published: April 2006

Branched and unbranched root hairs of Peperomia fraseri and P. blanda were examined by bright field transmission and fluorescence microscopy in the presence of the optical brightener Photine HV. Many highly fluorescent bands and spots were detected along the length of the root hairs, in addition to those in the expected site of tip growth at the apex of the hairs.
Growth, Sex Expression and Yield of Squash Melon (Citrullus vulgarisvar. fistulosus) as Influenced by 2(chloroethyl)phosphonic acid, 2,3,5‐tri‐iodobenzoic acid and (2‐chloroethyl) trimethyl‐ammonium chloride
Authors: SAIMBHI M. S. , THAKUR M. R.
Published: April 2006

Single aqueous sprays of 2(chloroethyl)phosphonic acid (CEPA) 250, 500 and 1000 mg/1; 2,3,5‐triiodobenzoic acid (TIBA) 25, 50 and 100 mg/1; and (2‐chloroethyl) trimethyl‐ammonium chloride (CCC) 250, 500 and 1000 mg/1 were applied to squash melon (Citrullus vulgaris Schrad. var. fistu‐losus Stocks.) at the 2–3 leaf stage. Though the final length of the main axis and number of lateral branches were not affected by any treatment, CEPA retarded growth of young plants by reducing the internodal length. It did not change the flowering pattern but delayed flowering and reduced the production of both pistillate and staminate flowers. However, it increased the per cent femaleness as a result of comparatively more suppression of staminate flowers. The TIBA 25 and 50 mg/1 and CCC 500 mg/1 did not affect the staminate flower production but increased the pistillate flowers, which increased the per cent femaleness. The CEPA decreased while both TIBA 25 and 50 mg/1, and CCC 500 mg/1 increased the number of fruits per plant and the yield. The mode of action of the chemicals has been discussed.
Cytokinins in Populus×robusta: Changes during Chilling and Bud Burst
Authors: HEWETT E. W. , WAREING P. F.
Published: April 2006

Cytokinin levels in sap and vegetative buds of Populus×robusta Schneid have been determined during chilling and bud burst. From non‐detectable levels in December and January, parallel increases in cytokinin levels occur in sap and buds during February and March, both in material from the field and that held at 2°C in the dark. The maximum in the sap occurs two weeks prior to natural bud burst, and 3 weeks, prior to the maximum attained in the buds. Excised twigs, forced to bud burst, show a similar pattern. The role of roots as a possible source of cytokinins is discussed.

Partition chromatography on Sephadex LH‐20 indicates that at least 5 cytokinins are present in buds, two of which have similar elution volumes to zeatin and zeatin riboside‐The main activity in the sap is confined to a zeatin riboside‐like component.
Ozone Induced Carbon Dioxide Evolution in Tobacco Callus Cultures
Authors: ANDERSON WILBUR C. , TAYLOR O. C.
Published: April 2006

Callus derived from Bel–W3 and Bel–B tobacco plants when exposed to ozone turned brown as a consequence of surface cell destruction. Ozone fumigations above a threshold concentration of 0.10 μl/1 for two hoars caused an increase in the rate of tissue carbon dioxide (CO2) evolution. The maximum increase in CO2 evolution was about 65 percent for both the ozone sensitive Bel–W3 and resistant Bel–B callus. However, the ozone dosage required to attain maximum increase in CO2 evolution was approximately two times greater for the resistant variety. Callus cultures that grew roots were observed to be more resistant to ozone. The addition of the antioxidant N,N'dipnenyl–p–phenylenediamine (DPPD) m the nutrient medium retarded ozone induced CO2 evolution.
Endogenous Levels of Growth Regulators and Their Relationship to the Rooting of Dahlia Cuttings
Authors: BIKAN I. , HALEVY A. H.
Published: April 2006

The relationship between the level of endogenous growth regulators and the rooting ability of dahlia cuttings was investigated. Easy‐to‐root vegetative cuttings were compared with difficult‐to‐root, flower bud bearing cuttings and the easy‐to‐root cv. Choot Hashani was compared with the difficnlt‐to‐root cv. Orpheo. No differences in the level of extracted or diffusable auxin, nor in the level of rooting cofactors, were found between easy‐to‐root and difficult‐to‐root cuttings. No activity could be found at the Rf zone corresponding to Cofactor 4 which is considered the main rooting cofactor in other plants. Higher inhibitor activity levels (assayed by the wheat coleoptile test and the mung bean rooting test) were found in difficult‐to‐root than in easily rooted cuttings. Furthermore, the inhibitor activity level in exadates from decapitated plants, was higher in esodates from plants which bore difficult‐to‐root cuttings than from plants bearing easy‐to‐root ones. Grafting of an easy‐to‐root plant onto a difficult‐to‐root stock caused inhibition of rooting in the cuttings taken from the scion. Results suggest that inhibitors formed in the root system, move upwards and accumulate in the plant, there causing the inhibition of rooting. Evidence from chromatographic comparisons and exogenous treatments with ABA indicate that the main inhibitor involved in the inhibition of rooting in dahlia cuttings is not ABA.
The Intra‐cellular Localization of the Herbicide Diphenamid in Corn Root .Tip
Authors: YAKLICH R. W. , SCOTT E. G.
Published: April 2006

The intra‐cellalar localization of the herbicide N,N‐dimethyl–2,2‐diphenylacetamide (diphenamid) was examined in 10 mm root tips of corn seedlings (Zea mays L. cv. Shawnee). Experiments are described which culminate in the observation that a significant, measurable effect on root growth occurs within 12 hours after treatment with diphenamid. Corn seedlings were then treated with 14‐C‐diphenamid for 12 hours and the 10 mm root tips excised and homogenized. By use of differential centrifugation and gel filtration, the root homogenate was separated into fractions; as follows; cell wall, mitochondria, microsomal, protein and eluate. The highest concentration of the herbicide was found in the root tips. Furthermore, most of the radioactivity was found in the eluate. Results are discussed as to localization of diphenamid in the microsomal and protein fraction and possible mode of action.
Hormonal Control of Differentiation of Shoots, Roots and Embryos in Leaf and Stem Cultures of Petunia inflata and Petunia hybrida
Authors: RAO P. S. , HANDRO W. , HARADA H.
Published: April 2006

Factors influencing adventitious bud and root development, callus induction and embryogenesis were investigated in stem and leaf cultures of Petunia inflata R. E. Fries and Petunia hybrida cv. Cascade and cv. Rose du ciel grown on a synthetic nutrient medium. Indoleacetic acid caused limited callus development and root formation whereas naphthaleneacetic acid Induced abundant roots. 2,4‐Dichlorophenoxyacetic acid promoted callus growth and differentiation of embryos which eventually developed into plantlets. Cytokinins such as benzyladenine, zeatin and kinetin induced bud development. A combination of auxins and cytokinins caused an interaction which was manifested in altered morphogenetic response. Thus 2,4‐dichlorophenoxyacetic acid in conjunction with benzyladenine caused suppression of bud development and retarded differentiation of embryos. Likewise, when benzyladenine was used with indoleacetic acid root development was totally inhibited and abundant buds were produced.
The Relationship between Chlorophyllide Accumulation, the Amount of Protochlorophyllide636 and Protochlorophyllide650 in Dark Grown Wheat Leaves Treated with δ‐Aminolevulinic Acid
Authors: SUNDQVIST CHRISTER
Published: April 2006

The influence of different amounts of protochlorophyl‐lide636 and protochlorophyllide350 on light Induced chloro‐phyllide formation was. studied in wheat leaves treated with δ‐aminolevulinic acid. The phototransformation of proto‐chlorophyllide was performed with weak red light. This transformation is unaffected by the δ‐aminolevulinic acid treatment, whilst the accumulation of chlorophyllide, both the rate and the amount, is greatly stimulated by moderate amounts of protochlorophyllide636. The presence of large amounts of protochlorophyllide636 decreases the rate of chlorophyllide formation, but increases the final amount of chloro‐phyllide formed. A decreased level of protochlorophyllide650, obtained by treatment with NaN3, results in a decreased transformation rate. Inhibitors; of protein synthesis do not seem to influence the transformation of protochlorophyllide636 to chlorophyllide, suggesting that no new synthesis of protein is required. The experimental results indicate that the final steps in chlorophyll biosynthesis are protochlorpnyllide636→ protochlorophyllide650→ chlorophyllide → chlorophyll.
Rapid Changes in Abscisic Acid‐like Inhibitors Following Alterations in Vine Leaf Water Potential
Authors: LOVEYS B. R. , CSIRO P. E. KRIEDEMANNI
Published: April 2006

Endogenous levels of abscisic acid‐like inhibitors doubled within 15 minutes of leaf excision in Vitis vinifera under laboratory conditions. At that stage water potential Ψ had fallen to ‐15 bars and stomatal closure was occurring. After prolonged stress (6 days and final Ψ ‐13 bars) inhibitor levels in intact vine leaves increased by a factor of 44 but showed a rapid decline following rewatering. Photosynthetic activity was not immediately restored, and its gradual recovery was not directly related to inhibitor level.
Diffusible and Extractable Gibberellins in Bean Cotyledons in Relation to Dwarfisni
Authors: GOTO N. , ESASHI Y.
Published: April 2006

Dwarfism in bean plants (Phaseolus vulgaris L.) is investigated in relation to the diffusible and extractable gibberel‐lins in cotyledonary tissues. These gibberellins were partitioned into four parts prior to thin layer chromatograplty: non‐acidic and acidic ethyl acetate fractions, and non‐acidic and acidic butanol fractions.

Cotyledonary segments from a tall plant (cv. Kentucky Wonder) seem to diffuse, preferentially acropetally, more gibberellins in each fraction than those from a dwarf plant (cv. Masterpiece). The diffusion increases with the length of the segments and decreases with period after sowing. From experiments on extraetable gibberellins, however, it is concluded that these phenomena actually result from differences in the gibbereliin contents of the tall and the dwarf plants, from differences in the gibberellin contents of the distal and proximal parts of cotyledons, and from the gibberellin contents before and after imbibition.

Ten kinds of gibberellin‐Iike substances are detectable in the diffusates, exudates and extracts from the cotyledons of both the plants; two in the non‐acidic ethyl acetate, three in the acidic ethyl acetate (GA1, GA6 and another), two in the non‐acidic butanol, and three in the acidic butanol frac—tion. They are almost identical in quality in the dwarf and tall plants, but in the latter they are more abundant in the cotyledons, particularly in their distal part.

With respect to the change in content during the period after sowing, the gibberellin‐Iike substances are classified in three groups; unchanging, decreasing (GA1, GA6, others) and increasing (butanol soluble glucosyl esters and glucosides of gibberellins)‐. The increase of glucose‐bound gibberellins and the decrease of free gibberellins during the sowing period suggest the occurrence of conversion. This is obvious only in the tall plants. The gibberellin content in cotyledons is higher in the tall plant than in the dwarf plant. Thus, the marked hypocotyl growth in the tall plants may be dependent on the higher content of gibberellins in their cotyledons and on the higner rate of conversion from free to bound forms.
Short‐ and Long‐term Effects of High Temperatures (47–49 °C) on Tobacco Leaves, in. Efflux and 32P Incorporation into Phospholipids
Authors: BENZIONI ALIZA , ITAI CHANAN
Published: April 2006

The efflux of 36C and 14C metabolites from heat‐treated tissue was studied. A two‐minute heat treatment at 47.5°C increased the leakiness of the membranes. The heat effect may be reversed either by treatment with kinetin or may occur spontaneously with time. The spontaneous reversal is tem—perature dependent and resembles the recovery of CO2 fixa—tion after heat treatment. The loss of membrane integrity is reflected in the rate of incorporation of 32P into phospho—lipids.
Changes in Endogenous Growth Kegulators in Loblolly Pine Seeds During the Process of Stratification and Germination
Authors: PAUL K. B. , PATEL C. S. , BISWAS P. K.
Published: April 2006

The seeds of loblolly pine (Pirns taeda L.) were cold‐stratified for 0, 14, 28, 42, and 56 days. Endogenous growth regulators were extracted from these seeds, and also from the germinating and the 28‐day warm stratified seeds. Partially purified extracts were separated on chromatographic paper. The chromatograms were cut into 10 equal segments, and these were tested for biological activity using three different btoassays.

The results indicated that the unstratified seeds and those stratified up to a period of 28 days contained very little or no growth promoter (GA‐like substances), and a relatively high concentration of an inhibitor (presumably abscisic acid), Following 42‐day stratification, the promoter concentration gradually increased while the inhibitor level fell almost to zero. A high level of promoter but no inhibitor was detected in germinating seeds.

No auxin‐like activity was noted in the unstratified seeds. This activity slowly increased up to a period of 28 days and remained at this level for the subsequent stratification periods. However, the activity greatly increased in the germinating seeds.

Very little changes in the levels of growth regulators were noted in warm‐stratified seeds as compared to the unstrati‐fied controls.
The After‐effect of Wind on the Photosynthesis and Transpiration of Festuca arundinacea
Authors: GRACE J. , THOMPSON J. R.
Published: April 2006

The after‐effect of wind on photosynthesis and transpiration of Festuca arundinacea Schreb, was determined. Following a period of exposure In a controlled environment wind tunnel the wind‐treated plants showed reduced rates of photosynthesis when compared with the controls under standard conditions. Evaporation from paper model tillers was measured and the boundary layer resistance was shown to be low in all but very low wind speeds. Analysis of CO2 and H2O diffusion pathways indicated that mesophyll resistance in wind‐treated plants was higher whilst leaf surface resistance was lower than in the controls. The high mesophyll resistance in the wind‐treated plants was attributed to reduced water content.
In Vivo Measurements of the Photo‐Oxidation of Chlorophyll Pigments in Dark Grown Wheat Leaves after Treatment with δ‐Aminolevulinic Acid
Authors: AXELSSON LENNART
Published: April 2006

Dark‐grown leaves of wheat fed with δ‐aminolevulinic acid accumulate protochlorophyllide636 in excess. After the leaves had been illuminated with high intensity red light (154 W × m−2) for half a minute, a treatment which blocks the phototrans‐formation protochlorophyllide chlorophyllide, the sensitivity of chlorophyllide and protochlorophyllide to light was examined.

The decrease in pigment content, caused by photo‐oxidation was found to be very close to a second order reaction. The second order “rate constant” for decrease in absorbance was found to be eight times greater for the formed chlorophyllide than for protochlorophyllide. The light intensity dependence of the decomposition was found to be linear within the intensity range used (E= 25 – 154 W × m−2). In samples in which the pigments had been heat denatured, it was possible to photodecompose the chlorophyllide without affecting the protochlorophyllide.

The results are discussed in connection with the theory of a photodynamic action involving oxygen in the singlet state (1ΔO2).
Carbonic Anhydrase Activity and Localization in Some Plant Species
Authors: TRIOLO L. , BAGNARA D. , ANSELMI L. , BASSANELLI C.
Published: April 2006

The aim of this work concerned the study of the differences in the carbonic anhydrase activity and localization between plant species, the photosynthesis of which is carried out according to the C3 and C4 pathways respectively.

The measurement of enzymatic activity was made with a titrimetric evaluation of the rate of the reaction CO2+ H2O ⇆ H++ HCO−3. The C3 plant species showed higher activities than the C4 species.

The localization of carbonic anhydrase was carried out with a histochemical method.

The carbonic anhydrase appeared in the chloroplasts both in the mesophyll and the bundle sheath without any difference between C3 and C4 plants.
Water Content and the Responsivity of Lettuce Seeds to Light
Authors: BERRIE ALEX. M. M. , PATERSON J. , WEST H. R.
Published: April 2006

Lettuce seed (Lactuca sativa L. cv. Grand Rapids) prevented from attaining maximum water content are still able to respond to irradiation if the seed moisture content is above 6%. When the limitation to water uptake is by immersion in a solution of either polyethylene glycol 400 (PEG 400), mannitol, or sucrose, the responsiveness of the seed is lessened.

With PEG 400 the molarity which reduces germination by about 50% is 0.03 while mannitol and sucrose must be present at 0.07M and 0.05 M respectively to bring about the same reduction.

While red light overcomes any additional effect 0.1 M mannitol and 0.025 M PEG 400 have on lettuce seed at 30°C (at which temperature the sample was positively photoblastic), irradiation did not overcome the effect of 0.1 M sucrose. Gibberellic acid did not have any effect on any of the treated seed.

The solutes used cannot be considered as inert. Some chemical activity is associated with them and it is unwise to consider using these molecules to establish a particular level of water potential in the liquid bathing the seed.
Rooting and the Metabolism of Nicotine in Tobacco Callus Cultures
Authors: PETERS J. E. , WU P. H. L. , SHARP W. R. , PADDOCK E. F.
Published: April 2006

The usefulness of exogenous nicotine as a factor in the induction of morphogenesis in a tobacco tissue culture medium has been demonstrated. Nicotiana rustica callus cell cultures were grown on a modified Murashige and Skoog medium with 2 mg/l indoleacetic acid (IAA) and 0.2 mg/l kinetin (MMS). Root morphogenesis was induced in roller tube callus cell cultures and solid callus cell cultures grown on MMS without kinetin supplemented with 10–100 mg/l nicotine.

Optimal nicotine concentration for root induction was 50 mg/l. Other tests using varying combinations of IAA, kinetin and nicotine produced no obvious morphogenesis, although some changes in the amount of callus growth and endogenous protein concentration did correlate with nicotine concentration relative to the presence of IAA and/or kinetin.

In liquid MMS medium, 14C‐nicotine was primarily incorporated into the protein fraction of cultured cells while primarily incorporated into the cell wall and/or cell membrane fraction of cells cultured on MMS without kinetin in the medium. In MMS without IAA and MMS without both IAA and kinetin, there was incorporation, but to a lesser extent in both the protein and the cell wall and/or cell membrane fractions.
Oscillatory Transpiration and Water Uptake of Avena Plants
Authors: BROGÅRDH T. , JOHNSSON A.
Published: April 2006

The action of D2O on oscillatory transpiration of Avena plants was investigated. D2O affects the amplitude and the period of the oscillations when given as a root medium to intact plants. The period is then dependent on the amplitude. From such experiments it is not possible to conclude whether the period change is simply due to the changed amplitude or to a change in the stomatal parameters.

When given to xylem compressed, excised plants without roots, the D2O hardly affects the amplitude of the oscillations but the period is increased. Thus, the period of the self‐sustained transpiratory oscillations is lengthened by D2O action on the stomatal parameters.

Phase and amplitude changes of the oscillatory transpiration caused by short D2O pulses given both to intact and excised plants, are discussed.

The following conclusion is emphasized: a substance which affects the root system can also cause profound changes in the stomatal water regulation.
A Broad Spectrum Tissue Culture Experiment with Tobacco (Nicotiana tabacum) Pith Tissue Callus
Authors: de FOSSARD R. A. , MYINT AUNG , LEE EDWARD C. M.
Published: April 2006

The composition and rationale of a broad spectrum tissue culture experiment involving 81 different media are described. Tobacco calluses sub‐cultured on media in this experiment were induced to form six main types of callus depending on the concentration levels of minerals, auxins, cytokinins, and sucrose, growth factors and amino acids in the medium. Only nine of the 81 media inhibited callus growth, and growth (increase in mass divided by initial mass of fresh matter) varied considerably reaching a maximum of nearly 200 after eight weeks on a medium high in minerals, cytokinins, sucrose, growth factors and amino acids and low in auxins. Five media induced regeneration from the calluses. This experiment is suggested as a potentially fruitful introductory test for many new or unresolved tissue culture situations.
Growth and Dormancy in Norway Spruce Ecotypes
Authors: HEIDE OLA M.
Published: April 2006

Height and radial growth of spruce in years n+ 1, n+ 2, and n+ 3 as affected by photoperiod and temperature in year n have been studied in controlled environments and in the field.

In agreement with common opinion apical shoot growth in year n+ 1 was strongly dependent on the temperature conditions prevailing in the period following budset in year n. This was found mainly to be a direct effect upon the differentiation of the shoot and needle primordia for next year's growth. A similar, although less pronounced effect, was found also on radial growth, possibly an indirect effect elicited through the effect on apical growth.

A rather wide temperature optimum of 18 to 24°C was found in three Norwegian ecotypes and a somewhat lower optimum (15 to 18 C) in an Austrian high altitude ecotype. The shorter the bud differentiation period, the higher was the temperature optimum in all ecotypes (heat sum effect). Photoperiod which is the main factor controlling the time of budset, thus had a great after‐effect.

The after‐effect was strongly modified by photoperiod and to a lesser extent also by temperature in the current growing season. It is concluded that in second‐year or older spruce plants the important effect of photoperiod in the current growing season is to control quantitatively and qualitatively the amount of secondary (lammas) shoot formation, and to modify shoot extension in the main growth flush. Longer photoperiods were needed for continuation or resumption of growth in second‐year plants than for maintenance of uninterrupted growth in first‐year seedlings.

Delayed flushing was observed in plants maturing at high temperatures, indicating that these plants had entered a deeper state of dormancy than those maturing at lower temperatures.

Also in years n+ 2 and n+ 3 apical and radical growth was significantly related to photoperiod and temperature conditions in year n. This effect gradually became an indirect one through the effects on general plant size (leaf and root area).

The results are discussed in the light of previous work in the field.
Guaiacyl Lignin Associated with Vessels in Aspen Callus Cultures
Authors: WOLTER KARL E. , HARKIN JOHN M. , KIRK T. KENT
Published: April 2006

Lignin from aspen (Populus tremuloides Michx.) tissue cultures containing only mature vessels and undifferentiated parenchymatous cells is exclusively of the guaiacyl type normally associated with gymnosperms. This supports the theory that the guaiacyl and syringyl lignin in angiosperm wood is compartmentalized, with guaiacyl lignin in vessels and syringyl lignin in fibers and ray cells.
Effects of Canavanine on Arginine Utilization in Plants with Special Reference to Mitotic Activity
Authors: WEAKS T. E.
Published: April 2006

Excised primary roots ofPhaseolus vulgarisL. were treated with canavanine and the effect on arginine utilization was studied. Arginine utilization was observed to be depressed to a low level by canavanine (1.8 × 10−4M) in rapidly dividing and growing tissues. In addition, canavanine inhibited arginine utilization to a lesser degree in root sections composed of mature and non‐dividing tissues. This demonstrated that canavanine inhibition is not limited to those tissues where active DNA synthesis occurs.

Canavanine was observed to inhibit the onset of mitosis in primary roots as evidenced by a significant reduction of the frequency of mitotic figures. In addition, this amino acid was found to affect the course of mitosis once it was initiated by altering the relative frequency of mitotic stages, decreasing the percentage of prophase figures and increasing the percentage observed in the telophase. An influence on the rate of spiralization and despiralization of the chromosomes is suggested. The effects on mitosis are probably related to growth‐inhibitory and toxic effects of canavanine. The possible function of canavine as an allelopathic substance is hypothesized.
Promoting Effect of Fusicoccin on Seed Germination
Authors: LADO PIERA , RASI‐CALDONGO FRANCA , COLOMBO ROBERTA
Published: April 2006

The effects of fusicoccin on the germination of dormant, light‐requiring or abscisic acid‐inhibited seeds has been investigated.

(1) Fusicoccin (10−6M) induces germination in dormant wheat seeds (Triticum durum cv. Cappelli; 1972 crop) and stimulates it in seeds already relieved from dormancy (1971 crop), with an effect similar to that of gibberellic acid.

(2) Fusicoccin (1.5 × 10−6M) is more active than the two phytohormones gibberellic acid and benzyladenine and than white light in stimulating light‐requiring lettuce seeds (Lactuca sativa cv. Grand Rapids) to germinate. Germination of radish seeds (Raphanus sativus) is also accelerated by fusicoccin, while benzyladenine and gibberellic acid are less active in this material.

(3) Fusicoccin (1.5 × 10−5M) removes almost completely the inhibitory effect of abscisic acid on germination of radish and lettuce seeds, whereas benzyladenine (10−4M) and gibberellic acid (3 × 10−4M) remove the inhibition only partially.

The possible relationship between these results and previous information on growth by cell enlargement is discussed in terms of the mechanism of action of fusicoccin as compared with natural hormones.
The Effect of Light on the Composition of DNA‐dependent RNA Polymerases of Verticillium agaricinum
Authors: VALADON L. R. G.
Published: April 2006

Four cellular RNA polymerases have been partially purified from cultures of Verticillium agaricinum using DEAE‐cellulose chromatography. Polymerases 1 and II are probably localised in the nucleolus and non‐nucleolar portion of the nucleus respectively, while III and IV are probably mitochondrial in origin. DNA stimulation and dependency on the four ribonucleoside triphosphates were shown to be characteristic of all four polymerases. The products of their activity were sensitive to ribonuclease digestion and to KOH hydrolysis. The time course study of all four polymerases showed a linear increase for 1 min followed by a plateau and a rapid decrease after 5 min.

Illumination of 4‐day‐old cultures increases the activity of RNA polymerase I, II, and III while only that of I and III is increased in 7‐day cultures. There is a similar increase in the amount of carotenoids produced by 4‐ and 7‐day‐old illuminated cultures. It is tempting therefore to suggest that ribosomes or mitochondria or both may be implicated in light‐induced cartogenesis.
Embryo Dormancy in Seeds of Acer platanoides
Authors: PINFIELD N. J. , DAVIES H. V. , STOBART A. K.
Published: April 2006

On dispersal the seed of Acer platanoides contained a dormant embryo, from which dormancy could be removed by chilling but not by hormone application. Dormany was deep in the embryonic axis, particularly in the radicle, but less so in the cotyledons. Under the storage conditions employed the dormancy pattern was modified so that during the subsequent incubation at 20°C, cotyledon expansion of isolated embryos from stored fruits was more rapid than that of isolated embryos from newly dispersed fruits. In addition, the dormancy of isolated embryos from fruits stored for several weeks could be broken by incubation in kinetin. It was concluded that embryo dormany in this seed can be divided into two phases, an initial phase when the embryo responds to chilling but not to cytokinins, and a later phase when cytokinins also become effective. The relationship between this transition and the apparent gradual reduction in the depth of embryo dormancy during storage is also discussed.

The chilling period necessary for dormancy breaking was reduced by kinetin and to a lesser extent by gibberellin, indicating a close relationship between the concentrations of these hormones and the chilling requirement.
A Kinetic Theory of First Order Cyclical Processes—Phytochrome Controlled Red Light Induced Cereal Leaf Unfolding Compared with Theory
Authors: DEUTCH BENTE , DEUTCH BERNHARD I.
Published: April 2006

The phytochrome controlled unfolding of cereal leaves was studied as a function of irradiation time and light intensity (narrowband red light) over a wide energy range (5 decades). With different intensities, a family of similarly shaped response curves appear with distinct time‐dependent maxima and minima. A theoretical kinetic model based upon a cyclical phytochrome photoconversion scheme has been calculated by us. The theoretical calculations and the experimental findings are in excellent agreement. The same model explains the early photoresponses (first maxima) as an effect of one active phytochrome form, P2, and the delayed photoresponses as an effect of a second active form Pn. The active transitory form, P2 (although it may not be the primary product), is formed upon light absorption from P1. The P2 decays by a first order dark reaction through several inactive intermediates to Pn (active). The effect of the intermediates is mainly to delay the production of the second active product. It is possible to identify the two active products, P2 and Pn, as Pfr and P*fr, respectively.

The presented cyclical phytochrome reaction scheme is a special case of a general first order kinetic cycle which includes all possible feed back loops. The latter scheme also has been calculated and programmed since it has a more general application.
The Effect of Chromium on the Photosynthesis and Growth of Diatoms and Green Algae
Authors: WIUM‐ANDERSEN SØREN
Published: April 2006

The effect of hexavalent chromium ions on the photosynthesis and growth of the diatom Nitzschia palea and the green alga Chlorella pyrenoidosa has been studied and compared with the effect of Cu and Hg. The effect of chromium is very similar to that of Cu and Hg, but it is more than one hundred times less toxic for the algae than copper. The toxicity of chromium is not counteracted by adding Fe to the culture solution. The problems regarding cleaning glass‐ware in dichromate‐sulphuric acid are discussed and it is strongly recommended to use other cleaning agents.
Protein Electrophoretic Pattern of Two Chlorella Mutants with Low and High Content of Sulphur‐Amino Acids
Authors: PASSERA CALVINO
Published: April 2006

Two mutants of Chlorella vulgaris characterized by high (HS) or low (LS) content of sulphur‐amino acids were compared to the wild strain with respect to their protein electrophoretic pattern.

Three new bands, not present in the LS and wild strains, were found in the HS mutant. In algae grown in the presence of 35S labelled sulphate two of these new bands showed a very high 35S specific activity. Some electrophoretic bands common to LS, HS, and wild strain, were present in different proportions and showed different levels of specific radioactivity for each strain. Therefore, mutational events appear to have affected both the amino acid composition of single proteins and the relative amount of proteins with high and low sulphate content.
Hétérogénéité de la Germination des Semences de Rumex crispus mise en Evidence et Essai d'Interprétation
Authors: LE DEUNFF Y.
Published: April 2006

Germination Heterogeneity of Rumex crispus L. seeds: Occurrence and Attempt at Interpretation.

Rumex crispus L. seeds, harvested without taking into account localization of mother plants or seed position on single plants differ in their response to unfavourable conditions inductive of dormancy as a function of their weight. During induction, application of potassium or GA3 prevents or reduces the entry into dormancy, suggesting that the observed heterogeneity is due to nutritional variations of the seeds in relation to their position on the mother plant.
Transport of Abscisic Acid‐2‐C‐14 in Intact Pea Seedlings
Authors: BELLANDI DEISE MAURI , DÖRFFLING KARL
Published: April 2006

When abscisic acid‐2‐C‐14 (AbA‐2‐C‐14), 1 μg in 5 μl 40% ethanol, is applied to the apical bud of light‐grown pea seedlings, C‐14 is translocated downwards only in very small amounts and does not enter the root. In contrast to this, C‐14 from indoleacetic acid‐C‐14 (IAA‐2‐C‐14) applied in the same manner is translocated to the root where it accumulates. When AbA‐2‐C‐14 is injected to the stem tissue at the apical bud, more labelled material is transported downwards than after application to the surface. Application of AbA‐2‐C‐14 to an expanded leaf results in considerable accumulation of C‐14 in the growing apical parts and in the lateral roots.
Variation du Taux d'Acide Chlorogénique dans les Bourgeons Végétatifs du Poirier au Cours de la Dormance Par
Authors: MELIN C. , BILLOT J. , DUPIN J. F. , PAULET P.
Published: April 2006

A spectrophotometric technique after paper chromatography was found adequate for quantitatively determining chlorogenic and caffeic acids in the vegetative apical buds of Pyrus communis L., variety ‘Passe‐Crassane’, de ľOrléanais. Using this method, significant changes in these polyphenols were shown to occur both in tissue concentration and total amount per bud, in samples collected during winter 1973–1974. A close relationship between chlorogenic acid concentration and state of dormancy of excised twigs was found.
Growth and Plating of Cell Suspension Cultures of Datura innoxia
Authors: ENGVILD K. C.
Published: April 2006

Suspension cultures of Datura innoxia Mill, were successfully grown on a modified Murashige and Skoog medium with 2,4–D, NAA or BAP as growth substances, provided the micronutrient levels were reduced to 1/10. Normal amounts of micronutrients were toxic. Attempts to identify the toxic elements did not succeed.

Cultures grew exponentially on a shaker at 27°C in the light. Their doubling times varied from 1.1 days on 2,4–D (10–6M) or NAA (10−5M)+ 1 g/1 casein hydrolysate to 2.7 days on BAP (3 × 10−7M) and 5.1 days on supraoptimal levels of 2,4‐D (10−5M). Cultures grew on NH4+‐N alone (from ammonium malate) or on NO3−‐N alone. Dry weight yield was proportional to the amount of nitrate‐N added (47 mg/mg N).

Filtered suspension cultures containing single cells (plating cultures) could be grown in agar in petri dishes when NAA or 2,4‐D were used as growth substances. Cells grew at densities above 500 units/ml in the agar. Most colonies grew from cell aggregates but division in single cells was observed. The highest plating efficiency was about 50% on 10−6 M 2,4‐D + 1 g/1 casein hydrolysate.
Lactate Dehydrogenase from Rhizobium. Purification and Role in Indole Metabolism
Authors: TRINCHANT JEAN‐CHARLES , RIGAUD JEAN
Published: April 2006

Cell‐free extracts of Rhizobium meliloti contain a soluble lactate dehydrogenase (LDH‐EC 1.1.1.27.). This was purified 250‐fold by ammonium sulfate precipitation and filtration on different Sephadex gels. This enzyme catalyses the reduction of pyruvate to lactate in the presence of NADH and for the first time we report its ability to reduce indole‐3‐pyruvic acid (IPyA) to indole‐3‐lactic acid (ILA). Optimal conditions for activity and Km values for both substrates were determined. In the presence of NAD the reverse reaction could be demonstrated with the aliphatic substrate (lactate), but under our conditions it was not possible to achieve the oxidation of ILA to IPyA. The role of this LDH in the indole metabolism is discussed and a general reaction scheme is suggested.
Photophysiology of Kalanchoë Seed Germination
Authors: ELDABH R. , FREDERICQ H. , MATON J. , DE GREEF J.
Published: April 2006

Germination of Kalanchoé blossfeldiana seeds is absolutely light‐requiring and needs repeated daily light periods.

With increasing length of the photoperiod there was a gradual escape from the far‐red inhibition. This escape depended also upon the duration of the far‐red exposure: 10‐second far‐red caused a strong inhibition after a 10‐ to 30‐minute photoperiod and did not inhibit after a 4‐hour day, although the effect of the latter was completely suppressed by 5 minutes far‐red. The action of a 12‐hour photoperiod was not reversed by 10 minutes far‐red but it was by 12 hours far‐red. Light intensity and temperature during the photoperiod were two other important factors influencing the escape from far‐red inhibition. The common features of this escape displayed in very different photomorphological responses are stressed.

In order to explain our results in terms of phytochrome action, we distinguish two effects of white light:

1) on the initial photoconversion of the inactive to the active PFR form

2) on the much slower transformation of PFR to a reacted form P*FR; the latter reaction can also proceed in darkness, but is enhanced by light and is dependent upon light intensity and temperature; this reacted phytochrome is not reversible by a brief far‐red illumination.
Embryo Development in Ripe Seeds of Eranthis hiemalis and its Relation to Gibberellic Acid
Authors: FROST‐CHRISTENSEN HENNING
Published: April 2006

The ripe seeds of Eranthis hiemalis (L.) Salisb., the winter aconite, contain undeveloped embryos. At 20–25°C the embryos grow only little, and the seeds do not germinate. Rapid embryo development starts if the seeds, after 3 weeks of “after‐ripening” at 20–25°C, are placed at low temperature, 3–4°C; germination then takes place after 2–3 months, Embryo development without germination occurs when the seeds are placed in gibberellic acid solutions at 20–25°C. Embryo development is inhibited at low temperature by the specific inhibitor of gibberellin biosynthesis, 2‐chlorethyl cholin chloride, but is restored by the simultaneous addition of gibberellic acid. It is suggested that one early effect of the cold is to bring about a synthesis of gibberellin.
Ethylene and the Responses to Light of Rice Seedlings
Authors: MILLER JOHN H. , MILLER PAULINE M.
Published: April 2006

The growth of rice seedlings (Oryza satira L.) in the presence of ethylene caused a change in the response to light of coleoptile elongation. In plants grown in air without added ethylene coleoptile elongation was promoted by red, far‐red and yellow‐green light only in very young seedlings; in older plants irradiation inhibited the growth of the coleoptile. The effect of growing plants in the presence of ethylene was to prolong the period during which light promoted coleoptile growth. Elongation of the first internode was inhibited by light whether or not the seedlings were grown in the presence of ethylene. A correlation existed between the growth effect of an irradiation and the initial decay rate of phytochrome which was established by the treatment. Regardless of wave length, light sources whose intensities were adjusted to produce a decay rate of about 10% per hour or less induced a moderate rate of coleoptile elongation which persisted for a relatively long period. Irradiation with red or yellow‐green light of higher intensity which produced a higher rate of phytochrome decay induced a higher rate of coleoptile elongation, but growth stopped after several hours. Other observations, however, showed that one cannot establish a general simple correlation between the rate of elongation of rice coleoptiles under light and the status of measurable phytochrome in the plant.
Growth and Dormancy Cycles in Citrus Bud Cultures and Their Hormonal Control
Authors: ALTMAN ARIE , GOREN RAPHAEL
Published: April 2006

An in vitro bud culture method was devised in order to better understand the control mechanism of Citrus bud development. This technique offers a new approach to the study of hormonal control of growth, dormancy and flowering cycles in perennial plants.

Buds were excised from orchard trees throughout the year, cultured on defined media for prolonged periods, and their vegetative growth responses to various growth hormones were determined. The buds proceeded with their vegetative development in vitro and achieved sprouting on a basal medium. The various growth regulators affected both the time required for sprouting (TRS) and the type of growth. In summer buds, IAA delayed sprouting, while GA enhanced it and caused shoot elongation. Cytokinins specifically induced the formation of numerous adventitious buds, whereas ABA completely inhibited sprouting; this inhibition, however, was reversible. A marked decrease in total protein and in the rate of its synthesis was evident during the first 20 days of sprouting induction and early bud growth.

The annual growth rhythm was determined in spring buds sampled and cultured throughout the year, and an innate dormancy of citrus buds was revealed. Both the dormancy and the sprouting periods of buds in vitro corresponded to the natural periods occurring under field conditions. The effect of exogenous IAA, GA and cytokinins on the TRS varied at different periods along the season, suggesting the concept of “critical levels” in the endogenous balance of hormones.
Role of Silicon in Diatom Metabolism
Authors: MEHARD CHARLES W. , SULLIVAN C. W. , AZAM FAROOQ , VOLCANI B. E.
Published: April 2006

The in vivo uptake of 31Si‐silicic acid and 68Ge‐germanic acid by cell organelles of Nitzschia alba Lewin and Lewin and Cylindrotheca fusiformis Reimann and Lewin was demonstrated. The organelles were isolated by fractionation of pre‐labeled cells by differential centrifugation in 0.4 M sucrose medium. Electron micrographs showed that the isolated organelles were intact, with the exception of the N. alba mitochondria which appeared swollen and the C. fusiformis chloroplasts which had ruptured outer membranes and lacked stroma material. The amount of 31Si or 68Ge per mg protein of the subcellular fractions decreased in the following general order for both organisms: cell wall, mitochondria, chloroplasts, vesicles, and microsomes. A portion of the 31Si or 68Ge in the organelle fractions could be extracted into a distilled water wash. The uptake of silicon by the organelles suggests that silicon may be involved in some processes of the compartmentalized systems of the cell.
Sulfate Uptake and Respiration of Aging Potato Discs Modified by Malonic Acid and Ultraviolet Radiation
Authors: HANEBUTH WILLIAM F. , CHASSON ROBERT M. , PITTMAN DAVID
Published: April 2006

The time course of sulfate uptake in relation to respiration is shown for aging slices of potato, Solanum tuberosum L. cv. Russet. For comparative purposes, a time course for phosphate uptake is also shown. Malonic acid depressed both the respiratory rise and the sulfate accumulating ability of aging discs. A low dose of ultraviolet radiation given at the onset of aging reduced sulfate uptake by one‐half without lowering respiration. We hypothesize that sulfate uptake is controlled by at least two mechanisms: one associated with oxidative metabolism and the other mediated by protein synthesis.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A.
Published: April 2006

Aescin in phosphate buffer reduced, to some extent, the production of 14CO2 from uniformly labelled glucose in mycelia of Ophiobolus graminis and Neurospora crassa, whereas aescin in succinate buffer had no effect. The enzymatic hydrolysis of sucrose was, however, severely affected, no production of 14CO2 from labelled sucrose being found after treatment of mycelia of O. graminis with 100 mg/l of aescin and N. crassa with 300 mg/l for 90 and 300 min, respectively. In Aspergillus niger the production of 14CO2 from glucose or sucrose was not affected. The ATPase in whole cells and isolated plasma membranes was not inhibited by the aescin treatment, on the contrary, the ATPase in whole cells of N. crassa was somewhat stimulated.
Lipids in Berseem Seed (Trifolium alexandrinum) during Germination as Affected by Gibberellic Acid and Maleic Hydrazide
Authors: BHATIA I. S. , SINGH I. P. , SUKHIJA P. S.
Published: April 2006

Lipid depletion of berseem seed treated with 100 mg/1 gibberellic acid or maleic hydrazide was studied during germination. During the first 3 days after germination there was little lipid consumption but thereafter the depletion of lipid was rapid. Gibberellic acid was found to enhance the lipid utilization of total lipids and triglyceride components during germination. On the other hand, maleic hydrazide reduced the utilization of triglycerides of the germinating seed. The rate of utilization was rapid for unsaturated fatty acids and slower for saturated ones in treated seeds as compared to untreated seeds.
Effect of Abscisic Acid on the Activities of Photosynthetic Enzymes and 14CO2 Fixation Products in Leaves of Pennisetum typhoides Seedlings
Authors: SANKHLA N. , HUBER W.
Published: April 2006

Abscisic acid inhibited the rate of 14CO2 fixation in leaves of Pennisetum typhoides (Burm. f.) Stapf & Hubbard seedlings, but increased the activities of phosphoenol‐pyruvate‐carboxylase and malic enzyme. The leaves of the seedlings grown in the presence of abscisic acid incorporated, in comparison to the control, more radioactivity in the fraction of organic acids, but less radioactivity was recorded in the amino acid fraction. On the other hand, gibberellic acid which also inhibits photosynthetic 14CO2 assimilation and decreases the activities of photosynthetic enzymes, favours greater incorporation in alanine, and reduces that in malate. It is deduced that bio‐regulants can greatly influence the flow of 14C into individual photosynthetic products. As in growth, abscisic and gibberellic acids in combination tended to antagonize each other in their effects on enzyme activity as well as in incorporation of 14CO2 into photosynthetic products.
Indoleacetic Acid Oxidases in Resting Cereal Grains
Authors: LAUREMA SEPPO
Published: April 2006

Peroxidases oxidizing indoleacetic acid (IAA) are present in the resting grains of barley, rye and wheat. The grains also contain small molecular inhibitors of the enzymes. A partly purified preparation of barley seed proteins was shown to contain at least two IAA oxidases about pI 5 and pI 10, mol. weight 30,000 and with a pH optimum 5.1–5.7. The enzymes require Mn2+, 2,4‐dichlorophenol and orthophosphate for the maximum activity. Attempts to separate IAA oxidase and peroxidase activities of the enzymes were unsuccessful.
The Effect of Cold Storage on Some Enzyme Activities in Tulip Bulbs
Authors: HAALAND ELLEN
Published: April 2006

The activities of α‐amylase, α‐glucan‐phosphorylase, and β‐fructofuranosidases were measured in an extract of soluble proteins of tulip bulbs of the cultivars “Apeldoorn” and “Paul Richter” stored for 2, 4, 6, 8, 10, and 12 weeks at 5°C. The enzyme activities increased during the first 4–6 weeks and then remained approximately constant during further storage at 5°C. 14C‐fructosyl‐sucrose oligosaccharides were identified after injection (into bulbs) of O14C‐U‐sucrose, thus showing fructosyl transferase activity.