bluuebunny/crossref_metadata_2025 huggingface dataset:
The State of Protochlorophyll and Chlorophyll in Corn Roots
Authors: BJÖRN L. O.
Published: April 2006

The protochlorophyll(ide) present in primary roots of dark‐grown corn (Zea mays) seedlings has an in vivo absorption maximum at 634 nm. Red light converts the pigment to chlorophyll(ide) a with an absorption maximum at 675 nm.
Photosynthesis of Conifers in Relation to Annual Growth Cycles and Dry Matter Production
Authors: FRY D. J. , PHILLIPS I. D. J.
Published: April 2006

Observations that deciduous larch species can show annual growth increments equal to or greater than evergreen conifers, and that the saturating light intensity for photosynthesis in needles of Larix leptolepis was almost twice those for several evergreen conifers, led to a study of the photosynthetic mechanism in L. leptolepis. Several features of photosynthesis in L. leptolepis placed this species in an intermediate position between classical C3 and C4 plants. Incorporation of 14C from 14CO2 by enzyme preparations of larch needles was eight times greater with PEP as substrate than with ribulose bis phosphate; a chlorophyll a/b ratio of 3.5 was obtained; needles possessed a green starch‐containing endodermis but with little orientation of mesophyll cells to this “bundle sheath”; no clear ultrastructural dimorphism was observed between chloroplasts of mesophyll and endodermal cells; a CO2‐compensation point of 20 μl‐l−1 was recorded; and the first measurable product of photosynthesis appeared to be malate rather than phospho‐glyceric acid. These results are discussed in relation to the deciduous habit of L. leptolepis and its high productivity in comparison with other conifers.
A Role for Auxin and Auxin Transport Inhibitors on the Ca Content of Artificially Induced Parthenocarpic Fruits
Authors: BANGERTH FRITZ
Published: April 2006

Artificially induced parthenocarpic fruits of apples, pears and tomatoes, as well as seeded fruits treated with 2,3,5‐triiodobenzoic acid, frequently show symptoms of Ca deficiency and a low Ca content. It was concluded that auxins, probably produced by the seeds, play a significant role in Ca translocation into fruits. Exogenous indoleacetic acid but not 4‐chlorophenoxyacetic acid applications could replace the effect of seeds in this respect. Auxin transport, rather than auxin accumulation, seems to be necessary for Ca transport, as can be concluded from the effect of auxin transport inhibitors.
The Effect of Root Formation on the Levels of Protein, Chlorophyll, RNA, DNA and Carbohydrates in Excised Cotyledons of Cucurbita pepo
Authors: MOHAMMAD A. M. S. , AL‐MASHHADANI Y.
Published: April 2006

In attached cotyledons of Cucurbita pepo L. protein, chlorophyll, RNA, DNA and carbohydrates were found to increase to a maximum level 14 days after commencement of germination, followed by a sharp decline thereafter. Cotyledons excised and planted in a nutrient solution 14 days after sowing showed maximum levels of protein, chlorophyll, RNA, DNA and soluble and insoluble sugars 52 days after planting. The increase in these compounds coincides with the full development of the root system. Excision earlier or later than 14 days resulted in lower levels of protein and other compounds. The decrease in the level after 52 days was parallel to the senescing phase of the cotyledons.
The Critical Oxygen Pressures for Respiration in Intact Plants
Authors: ARMSTRONG W. , GAYNARD T. J.
Published: April 2006

Two methods for determining critical respiratory oxygen pressure in whole plants are described.

By a polarographic method involving the use of cylindrical platinum electrodes the following critical oxygen pressures for root respiration were found: Rice (cv. Norin 36). 0.024 atm: Rice (cv. Norm 37). 0.026 atm: Eriophorum angustifolium. 0.02 atm. These values contrast markedly with those obtained in vitro, and support earlier criticisms of in vitro measurements: they call into question the use of such data in the modelling of root aeration. When the results were assessed by an electrical analogue system, it was concluded that the respiratory activity in the intact root does not follow the normally accepted hyperbolic relationship with oxygen partial pressure. The experimental data were simulated most closely by assuming the critical oxygen pressure to be a function of respiratory responses in the low porosity (high diffusional impedance) tissues of the root meristem and stele, and respiratory activity in the moderately porous root cortex to be unaffected at values greater than 0.001 atm.

A critical oxygen pressure of 0.025–0.04 atm for E. angustifolium was found from analyses of the gas phase oxygen in the leaves of whole plants after submergence in the dark. It was concluded that the higher value found by this method was most likely a function of respiratory responses in root tissue remote from the leaf and should not be regarded as the critical oxygen pressure for leaf respiration. The form of the oxygen concentration vs. time plot again suggested a very much lower critical oxygen pressure for certain of the plant tissues.
Simultaneous Measurement of the Bioelectric Potential of the Cell Wall and the Vacuoles during the Oscillatory Response to the Nitella Cell
Authors: RADENOVIĆ Č. , VUČINIĆ Ž.
Published: April 2006

Simultaneous measurements of bioelectric potentials of the vacuole and cell wall in cells of Nitella mucronata were made by inserting glass microelectrodes into the vacuole and cell wall respeclively. During the oscillation of the bioelectric potential of the vacuole. induced by sudden changes of the external bathing solution or by the impalement of the cell with a microelectrode. the cell wall potential also exhibited fluctuations of variable intensities in phase and concomitant with spikes of the vacuolar potential oscillation. However, the polarity of the pulses of the cell wall potential was reverse to that of the spikes of the vacuolar potential. These results suggest that the same event is registered at both sides of the plasmalemma membrane across which these phenomena are occurring. The results also support the voltage clamp and tracer flux measurements on these cells which indicate that during the generation of single action potentials, induced by current, the plasma lemma transiently increases its permeability to Cl− and K+ ions expelling them from the cell. The variable intensity of the transient hyperpolarizations of the cell wall potential is explained by the distance of the microelectrode in the cell wall from the plasmalemma.
Carbon Dioxide as an Essential Requirement for Cultured Sycamore Cells
Authors: GATHERCOLE R. W. E. , MANSFIELD K. J. , STREET H. E.
Published: April 2006

Carbon dioxide (optimum concentration c. 1.0%) is essential to the initiation of the growth in suspension culture or on agar plates of cultured sycamore cells. By effective flushing of the cultures with CO2‐free air it is possible to demonstrate this requirement with initial cell densities up to 50 × 103 cells ml−1. This growth‐promoting activity of carbon dioxide is not related to any effect it may have on the pH of the culture medium. The cells fix applied carbon dioxide into organic and amino acids but attempts to replace the carbon dioxide requirement by non‐toxic levels of organic or amino acids have not been successful.
Growth and Sucrose Metabolism of Carrot Callus Strains with Normal and Low Acid Invertase Activity
Authors: PARR D. R. , EDELMAN J. , HAWKER J. S.
Published: April 2006

The properties of two strains of carrot (Daucus carota) callus are presented. One has a very low acid invertase activity which is accompanied by differences in morphology and metabolic rate, but not in growth rate. We conclude that one of the main functions of plant acid invertases is in controlling the levels of sugars which, by interaction with hormones, affect differentiation, both morphological and biochemical. The effect of tris on sucrose metabolizing enzymes, and the cause of the “sucrose effect” are considered.
Isolation and Analysis of Protein Bodies from Cotyledons of Lablab purpureus and Phaseolus vulgaris (Leguminoseae)
Authors: MIÈGE MARIE‐NOËLLE , MASCHERPA JEAN‐MICHEL
Published: April 2006

Protein bodies, isolated by differential and isopycnic centrifugation, have been observed in transmission and scanning electron microscope and biochemically analysed. The powders of the axes and of the cotyledons contain numerous protein bodies, which in the scanning microscope appear to be surrounded by a more or less torn membrane. The proportion of intact, isolated protein bodies is influenced by the grinding methods, but even in the best conditions soaking disaggregates the majority of them. After isopycnic centrifugation, their debris gather in different density zones. Analyses of each zone have revealed that the caseinases are associated with particles of higher density than are peptidases and trypsin inhibitors. A minority population of small‐size protein bodies resists the homogenization and fractioning modalities. A double origin of the protein bodies is considered.
Environmentally Induced Changes in the Cell Walls of Tomato Leaves in Relation to Cell and Protoplast Release
Authors: CASSELLS ALAN C. , BARLASS MARTIN
Published: April 2006

Factors involved in the isolation of protoplasts from the leaves of tomato plants grown over a wide range of environmental conditions have been studied. Increases in calcium pectate in summer grown (“hard”) plants are suggested as a barrier to cell wall degradation. A one‐step method involving the addition of sodium citrate to pectinase plus cellulase gives high yield of protoplasts from hard plants.

Attempts to convert isolated palisade cells to protoplasts have failed.

The plant culture conditions are described such that protoplasts may be isolated throughout the year using low enzyme concentrations.
Photosynthetic Electron Transport in Plants of Sitka Spruce Subjected to Differing Light Environments during Growth
Authors: LEWANDOWSKA M. , HART J. W. , JARVIS P. G.
Published: April 2006

Seedlings of Picea sitchensis (Bong.) Carr. (Sitka spruce) have been grown in four different light regimes in growth chambers. Chloroplast fragments have been isolated from the needles and Photosystem I and Photosystem II activities measured. Measurements were made at eight photon flux densities giving light response curves for photosystem activity in needles grown in the four different light regimes. Chlorophyll concentration was higher in needles from the low cultivation light environments than in those from the high light environments. Photosystem activity was higher in needles from the high cultivation light environments. Evidence that Photosystem I was limiting photosynthesis in needles grown in the high light environments was obtained.
The Geotropic Curvature in Roots of Norway Spruce (Picea abies) Containing Anthocyanins
Authors: IVERSEN TOR‐HENNING , SIEGEL KNUT
Published: April 2006

Seedlings of Norway spruce (Picea abies L.) have been found to synthesize anthocyanins in the root tips as well as in the hypocotyls upon irradiation with white light when kept at 4°C for 6–8 days. In addition, it has also been found that the elongation and the geotropic curvature of spruce roots are dependent on the light conditions.

The course of the geotropic curvature in spruce roots containing anthocyanins has been followed during a period of 5 h, in which the seedlings were geotropically stimulated continuously in the horizontal position. When the stimulation was performed in white light and in darkness at 21°C, significantly larger curvatures were observed in the roots pretreated at 4°C in darkness than in the roots containing anthocyanins. The specific curvature (curvature in degrees per mm elongation), however, was approximately the same in both types of roots stimulated in white light. This was due to a retarded elongation of the roots pretreated with light at 4°C and containing anthocyanins. A smaller difference in elongation rate between roots with and without anthocyanins was observed in the dark than in the light, but even in the dark the anthocyanin‐containing roots grew more slowly than roots without anthocyanins.

In order to find out if it is the anthocyanin content or the illumination which affects the elongation and geotropic curvature in the roots, a series of similar experiments was performed using cress seedlings grown at 4°C in light or darkness. Roots of cress seedlings cultivated under conditions which would induce anthocyanin formation in spruce roots exhibited the highest geotropic responses both in light and darkness as compared to cress seedlings grown at 4°C in darkness.

As in the case of spruce roots an increase in elongation was observed in cress roots illuminated during the geotropic stimulation. These similarities in the behaviour made it relevant to compare the development of the geotropic curvature in cress and spruce roots.
Flower Bud Atrophy in Baccara Roses. V. The Effect of Different Growth Substances on Flowering
Authors: ZIESLIN N. , HALEVY A. H.
Published: April 2006

The effect of various growth regulators on the atrophy of terminal flower buds was tested on Baccara roses. Treatments with gibberellic acid (GA) and 2‐chloroethyl trimethyl ammonium chloride (CCC) reduced the atrophy of the flowers. The application of 2‐chloroethyl phosphonic acid (CEPA) to the buds enhanced abortion, and the effect was more marked on the lower than on the upper shoot. The stage most sensitive to CEPA was when the shoots were 8–35 cm long. Treatment with abscisic acid (ABA) had no effect of the degree of “blindness”, nor did kinetin applied to the apex affect flowering. Spraying with benzyl adenine increased both the rate of sprouting of the lateral buds and the extent of “blindness” of the sprouting shoots, but did not reduce the number of flowers per branch.
Importance of Photosynthetic Cotyledons for Early Growth of Woody Angiosperms
Authors: MARSHALL P. E. , KOZLOWSKI T. T.
Published: April 2006

At various times after seed germination, epigeous cotyledons were excised or treated with DCMU (3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea) to inhibit cotyledon photosynthesis of seedlings of Acer negundo L., Ailanthus altissima (Mill.) Swingle, Eucalyptus globulus Labill., Fraxinus pennsylvanica Marsh., Robinia pseudacacia L., and Ulmus americana L. In all species, DCMU inhibited expansion of cotyledons, elongation of roots, initiation of lateral roots, and expansion of foliage leaves. During the first 10 days after radicle emergence decotylization also variously inhibited growth of plant parts. Photosynthetic rates per cotyledon varied among species in the following order: Robinia pseudacacia > Ailanthus altissima≥Fraxinus pennsylvanica > Ulmus americana. The length of time that cotyledon photosynthesis contributed to growth of axial parts varied widely among species.
Uptake of Gibberellic Acid in Intact and Scarified Seeds of Barbarea vulgaris
Authors: TAYLORSON R. B.
Published: April 2006

Uptake of gibberellic acid as a function of duration of exposure, external concentration, and seed lot was measured in seeds of yellow rocket (Barbarea vulgaris R. Br.) by means of lettuce hypocotyl bioassays of the acidic, basic, or neutral fractions of seed extracts and by uptake of 14C‐GA3. In intact seeds, where mM levels of GA3 promoted only 25% germination, uptake was completed within 24 h of exposure. The maximum uptake was about 0.2% of external amount. Although germination promotion by GA3 differed among seedlots of yellow rocket, relative uptake (percentage of the external GA3) was nearly the same.

The relative rate of uptake of GA3 was similar for scarified and intact seeds, but germination was promoted in scarified seeds by much lower levels of GA3 than in intact seeds. Total uptake in scarified seeds was much higher, however (about 10% of the external amount). In seeds imbibed in H2O, practically no endogenous GA‐like activity was detected in either the acidic, basic, or neutral fractions.

It was also apparent that intact seeds could take up quantities of GA3 that failed to promote germination, but were comparable to quantities that promoted germination in scarified seeds.
Extraction and Recovery of Cytokinin Glucosides by Means of a Cation Exchange Resin
Authors: VAN STADEN J.
Published: April 2006

Cytokinin glucosides can be extracted rapidly and efficiently from plant material by means of the acid cation exchange resin Dowex 50W X8 (Baker's Analysed Reagent). In the present investigation no evidence could be found that these cytokinins are hydrolysed or retained by the Dowex resin.
Adenosine Triphosphatases Bound to Plasmalemma, Mitochondria, and Microsomes or Present in the Cytoplasmic Phase from Potato Tubers
Authors: JOLLIOT ALAIN , DEMANDRE CHANTAL , MAZLIAK PAUL
Published: April 2006

Between pH 4–10, basal ATPase activity, measured in the absence of mineral ions, was 10 to 100 times higher in the final cytoplasmic supernatant from potato tuber homogenates than in the membraneous fractions (purified plasmalemma, purified mitochondria and microsomes). The soluble ATPase was slightly inhibited, whereas the membrane‐bound ATPases were all stimulated by Mg2+ ions. A further stimulation by Na+ or K+ ions was only observed in purified plasmalemma or mitochondria, at alkaline pH (7.5–9.5). At a fixed (Na++ K+) concentrations (80 mM), this last stimulation was much greater in purified mitochondria (350%) than in plasmalemma (33%); it also increased with (Na++ K+) concentrations up to 200 mM in mitochondria whereas, in plasmalemma, it was roughly constant for monovalent ion concentrations between 20 and 200 mM.

General properties of the plasma membrane‐bound ATPase have been determined, i.e. substrate specificity, activity variations with quantity of substrate, temperature, pH, etc. Divalent cations stimulated strongly the ATPase in the following order: Mn2+ > Mg2+ > Ca2+. The maximum ATP hydrolysis velocity for that part of ATPase activity which is strictly dependent on Mg2+ ions was 3.85 μmol × mg−1 protein × h−1. This plasma membrane ATPase was not sensitive to ouabaïn or to oligomycin.
Effect of Vanadium Pentoxide on the Incorporation of (2‐14C)‐Acetate into Fungal Lipids
Authors: ANEKWE GREGORY E.
Published: April 2006

Mycelia of Glomerella cingulata grown in the presence of vanadium pentoxide (V2O5), incorporated many times less (2‐14C)‐acetate into their lipids than mycelia of the same organism grown in the absence of V2O5. All neutral and polar lipid fractions investigated were affected. These data suggested that V2O5 depressed lipid biosynthesis in G. cingulata.
Chemical Examination of Viable and Non‐Viable Rice Seeds
Authors: CHATTERJEE A. , SAHA P. K. , GUPTA PADMA DAS , GANGULY S. N. , SIRCAR S. M.
Published: April 2006

A chemical examination has revealed four phenolic compounds in nonviable rice seeds (Oryza sativa L.). Their inhibitory bioactivity in the wheat coleoptile extension bioassay and the absence of these components in viable seeds have confirmed the relation of the phenolics with nonviability of the seeds. The compounds isolated from nonviable rice seeds were Kaempferol‐4′‐methyl ether, Kaempferol, quercetin and caffeic acid as identified on the basis of physical and chemical evidences.
Absorption and Re‐distribution of Nitrogen during Growth and Development of Field Bean, Vicia faba
Authors: COOPER D. R. , HILL‐COTTINGHAM D. G. , LLOYD‐JONES C. P.
Published: April 2006

The absorption of nitrate by field bean plants at different times of development was investigated to determine the distribution and subsequent utilization of N up to the maturity of the beans.

Nodulated plants were grown in sand culture and pulse‐labelled with 15NO3 for 4 short periods during development. Whole plants were sampled at intervals until maturity and analysed for total nitrogen and 15N.

There was a rapid increase in the bean dry weight and total N after fruit set and, at maturity, the beans contained about three times as much N as had ever been in the rest of the plant. Nitrate absorption continued steadily throughout plant development but nodule N fixation made a progressively greater contribution to the total N in the plant. Over a quarter of the total 15N absorbed was found in the roots immediately after each treatment and little of this was subsequently translocated upwards in spite of the large increase in shoot N taking place. Above ground the most powerful “sink” for recently absorbed and redistributed N was initially the youngest vegetative tissue. However after fruit set competition developed between the growing tip and the developing beans until at the later stages the beans became the more powerful. Quantitatively redistribution made only a small contribution to bean N.
The Action of Fusicoccin Alone and with Some Plant Growth Substances on Tobacco Tissue Cultures
Authors: SPARAPANO LORENZO
Published: April 2006

The interaction of fusicoccin, a terpenoid glucoside produced by Fusicoccum amygdali Del., and some plant growth regulating substances, i.e., indole‐3‐acetic acid, kinetin, 2,4‐dichlorophenoxy‐acetic acid and abscisic acid, was investigated on pith and sub‐cultured callus cultures of Nicotiana tabacum L. Addition of fusicoccin alone to the basal medium, either in the light or in the dark, caused a fairly good development of tobacco callus. When fusicoccin and kinetin were simultaneously added to the culture medium, the callus growth increased. However, fusicoccin in combination with indole‐3‐acetic acid caused limited callus development: the tissue appeared brown and reduced in volume. Addition of fusicoccin with 2,4‐dichlorophenoxyacetic acid stimulated growth of callus and chlorophyll was formed under light. Finally, abscisic acid did not interfere with the effect of fusicoccin on the callus growth.
The Photostability of Different Chlorophyll Forms in Dark Grown Leaves of Wheat
Authors: AXELSSON LENNART
Published: April 2006

The stability against high intensity irradiation (red light, 700 W m−2) was investigated for the chlorophyll(ide) pigments formed after the primary photoreduction of the protochlorophyll(ide) in dark grown leaves of wheat. After photoreduction, most of the chlorophyll(ide) exists in a form with an absorption maximum at 684 nm. This form is gradually transformed into a form with an absorption maximum at 673 nm (the Shibata shift). It was possible to ascribe a specific photostability to each of the pigment forms. This photostability was higher for the 673‐form than for the 684‐form. A red‐shift in the absorption maximum following upon the Shibata shift, reflects the successive transformation of the 673‐form into other pigment forms, which were quite photostable at the intensity used.
The Photostability of Different Chlorophyll Forms in Dark Grown Leaves of Wheat
Authors: AXELSSON LENNART
Published: April 2006

The stability against high intensity irradiation (red light, 700 W m −2) was investigated for the chlorophyll(ide) pigments formed after photoreduction of the protochlorophyllide of dark grown leaves of wheat.

The reaction kinetics for the photodecomposition of the 673‐form was the same as for photooxidation of chlorophyll in vitro, which is a second order reaction with respect to the chlorophyll concentration. The 684‐form was photodecomposed in a first order reaction. This deviation from the in vitro kinetics may be explained by a gradual ‘decrease’ in the photostability of the pigment during the irradiation, possibly dependent on a gradual increase in the internal concentration (‘aggregation’) of the pigment. The photo‐stability was found to be 4–5 times higher for the 673‐form than for the 684‐form (the half‐lives were 10.5 and 2.3 min respectively). Connections between the presence of photosynthetic activity and the reaction kinetics for the photodecomposition of the chlorophyll(ide) are discussed.
Combined Effects of Abscisic Acid and Sucrose on Growth and Senescence of Rose Flowers
Authors: BOROCHOV AMIHUD , MAYAK SHIMON , HALEVY ABRAHAM H.
Published: April 2006

The effects of sucrose and abscisic acid (ABA) and their interaction on development and senescence of petals were studied with leafless roses cultivar Super Star. Sucrose and ABA had opposing effects on the cut flowers. Sucrose retarded and ABA promoted processes associated with senescence: wilting, increase in pH, “blueing” and decrease in protein content of petals. These opposing effects are mutually antagonized when both chemicals are applied. ABA applied to flowers cut at the bud stage, promoted the rate of petal growth (but not their final size), increased respiration and caused a decrease in sucrose and an increase in level of reducing sugars.

It is suggested that one way by which ABA accelerates senescence of cut roses is by promoting petal growth and respiration, thus decreasing the carbohydrate level in the petals and triggering the chain of metabolic processes leading to aging.
Occurrence of a Cytokinin Glucoside in the Leaves and in Honeydew of Salix babylonica
Authors: VAN STADEN J.
Published: April 2006

Honeydew and leaf extracts from Salix babylonica indicate that large quantities of cytokinin are present in the leaves and are transported through the phloem of this plant during late autumn. The active compound in the extracts could be hydrolysed with β‐glucosidase, whereafter it showed the same chromatographic behaviour as zeatin. It is proposed that cytokinins in the leaves are converted to the glucoside and then redistributed to the rest of the plant organs where it is stored.
Rapid, Blue‐Light‐Induced Transpiration Response Restricted to Plants with Grass‐like Stomata
Authors: JOHNSSON MARIANNE , ISSAIAS SUSANNA , BROGARDH T. , JOHNSSON A.
Published: April 2006

It is shown that the response of transpiration to light is different in species from Gramineae and Cyperaceae compared to species from other families. Blue light (380–500 nm) causes both a rapid response (rise time 2 min) and a slow response (rise time 5 to 10 min) in species from these two families but induces only a slow response in other families. Red light results only in a slow response in all plants investigated.

It is hypothesized that the rapid response to blue light is due to the special anatomy and/or function of the so‐called grass‐like (graminaceous) stomata of plants belonging to Gramineae or Cyperaceae.
Kinetics of Potassium and Magnesium Uptake by Intact Soybean Roots
Authors: JOSEPH R. ANTONI , VAN HAI TANG
Published: April 2006

The kinetics of uptake of K+ and Mg2+ were studied by using intact soybean [Glycine max (L.) Merr. cv. Amsoy] roots. Uptake of K+ in the concentration range 1.29 × 10−5 to 1.82 × 10−3 M can be represented by two phases of a single, multiphasic mechanism. Similarly, uptake of Mg2+ in the concentration range 4.10 × 10−6 to 2.49 × 10−4M was biphasic.
Characterization of the Aminoacylation of Cytoplasmic Transfer Ribonucleic Acids from Germinating Soybeans
Authors: TESTER C. F.
Published: April 2006

Extracts from germinating soybean [Glycine max (L.) Merr.] cotyledons were assayed for aminoacyl‐tRNA formation. This esterification reaction depends on several factors, which must be determined and controlled for each system investigated. The reaction was maximum when the Mg: ATP ratio was 12.5 and concentrations were 9 and 0.72 mM, respectively. The optimum temperature for the in vitro reaction was 25°C. In addition, the reaction was inhibited by inorganic pyrophosphate and magnesium could be replaced by spermidine.
Activities of Various Peptidases in Cotyledons of Germinating Peanut (Arachis hypogaea)
Authors: MIKOLA JUHANI
Published: April 2006

The activities of several carboxy‐ and aminopeptidases were assayed in extracts prepared from the cotyledons of resting and germinating peanut seeds as well as from growing and fully differentiated peanut leaves.

Carboxypeptidases acting on two carbobenzoxydipeptides Z‐Phe‐Ala and Z‐Ala‐Phe at pH 5.2 showed minimal activities in “resting” cotyledons, and only slight increases occurred during 7‐day germination at 28°C. In peanut leaves the corresponding activities were quite high, about 20‐ and 6‐fold compared to “germinating” cotyledons.

Peptidases acting on Leu‐Tyr at pH 8.6 and on Ala‐Gly at pH 7.8 were highly active in resting cotyledons, and the activities remained essentially constant during germination; corresponding activities in leaves were much smaller (about 15–25% of those in cotyledons).

“Naphthylamidases” hydrolyzing the β‐naphthylamides of Phe, Leu, and Arg at pH 7.2, were also highly active in resting cotyledons; during germination the first activity stayed at a constant level while the other two decreased progressively. Leaves showed relatively high activities on Phe‐bT‐NA and Leu‐β‐NA but only minimal activity on Arg‐β‐NA.

It is tentatively concluded that the peptidases acting on Leu‐Tyr and on Ala‐Gly as well as the naphthylamidases function in the mobilization of the reserve proteins of peanut cotyledons during germination. The carboxypeptidases, in contrast, do not seem to play a major role in this process.
Two Sites of Hormonal Action during Germination of Chenopodium album Seeds
Authors: KARSSEN C. M.
Published: April 2006

During the overall germination process in the light‐requiring seeds of Chenopodium album L. two sites of hormonal action can be distinguished.

The start of visible growth is induced in darkness by the gibberellins 4 and 7 (GA4+7) or by ethylene. Added cytokinins are inactive although 8‐14C‐kinetin shows rapid penetration into the seed and rapid turnover. The induction of growth by GA4+7 and the uptake of 8‐methylene‐14C‐GA3 are enhanced at lower pH values. Prolonged incubation in darkness results in a decreased responsiveness of the seeds towards GA4+7 and ethylene.

A second site of hormonal action is located during the progress of growth inside the covering structures. ABA inhibits radicle growth, while GA4+7, GA3, kinetin, zeatin and ethylene reduce the inhibition.
Chemical Factors Affecting Palmelloid‐Forming Activity of Chloroplatinic Acid on Chlamydomonas eugametos
Authors: NAKAMURA KAZUO , SAKON MARGARET , HATANAKA MUREEN K.
Published: April 2006

In order to elucidate the physiological mechanism of palmelloid formation of the unicellular green alga Chlamydomonas eugametos by chloroplatinic acid, the factors causing inhibition of the palmelloid formation were studied in various media. Chloroplatinic acid lost its palmelloid‐forming effect in the presence of nitrite ion and amines having a second functional group. Nitrate, potassium, and sodium ions and monofunctional amines were without influence on the effect of chloroplatinic acid. These results indicate that the active form of platinum (IV) may undergo ligand substitution, the resulting complex being unable to cause palmelloid formation.
Nitrogen Constituents in Manganese‐Deficient Lemon Leaves
Authors: LERER MICHAEL , BAR‐AKIVA AVIGDOR
Published: April 2006

Total (Kjeldahl) nitrogen content of manganese‐deficient lemon leaves was found to be about 40% higher (on a dry weight basis) than in the analog control leaves. The nitrate‐N content rose in the deficient leaves from 18.2 mg/100 g to 95.6 mg/100 g dry weight. Among the N constituents studied, the free amino acids increased by about 42%, the protein amino acids by about 22%, and the total protein by more than 22%, all on a fresh weight basis. Acrylamide gel electrophoresis and ammonium sulfate fractionation showed qualitative differences in the various proteins. The increase of the protein fraction in the ‐Mn leaves may be attributed in part to the decrease of dry matter in these leaves (25.8% as compared to 30.7% in the control leaves) and in part to accumulation of apparent proteinous material in manganese‐deficient tissues.
Variation of Alkaloid Production in Nicotiana rustica Callus Cultures
Authors: TABATA MAMORU , HIRAOKA NOBORU
Published: April 2006

Callus cultures have been established from the seed, root and leaf of Nicotiana rustica L. var. brasilia in a synthetic medium containing 1 μM 2,4‐D and μM kinetin. These callus tissues behaved similarly not only in growth and organogenesis but also in nicotine production. The nicotine contents of callus cultures, which were in the order of 0.25–0.58% of dry weight during a few passages subsequent to callus induction, rapidly decreased to trace amounts in succeeding subcultures in association with the decline of the root‐regenerating activity. On the other hand, free cells prepared from a callus tissue in the third passage developed into individual clones showing wide differences in growth and nicotine production. One of these clones gave rise to a relatively stable strain which is capable of producing nicotine at a high rate (0.29% of dry weight) in the absence of organization. The significance of these findings is discussed in connection with some results which have been reported for other callus cultures of Nicotiana species.
Comparison of N6‐benzyladenine and N‐4‐pyridyl‐N′‐phenylurea Effects on Lateral Bud Growth, Flowering and Seed Production of Brussels Sprouts (Brassica oleracea var. gemmifera)
Authors: THOMAS T. H.
Published: April 2006

N‐4‐pyridyl‐N′‐phenyl urea (NC5392) showed similar activity to N6‐benzyladenine (BA) in stimulating lateral bud development on Brussels sprout (Brassica oleracea var. gemmifera) seedlings particularly on de‐rooted plants, but increased average bud weight far more than did BA. Both compounds increased flowering of young plants given an insufficient cold stimulus and seeds from treated plants showed a higher germination percentage than those from untreated plants.
Effect of Gibberellic Acid and Some Phenols on Flowering of Impatiens balsamina, a Qualitative Short‐day Plant
Authors: NANDA K. K. , KUMAR SURINDER , SOOD VINI
Published: April 2006

GA3 as well as SA (salicylic acid) and β‐N (β‐naphthol) induce floral buds in Impatiens balsamina under strictly non‐inductive photoperiods. The floral bud initiation is accelerated when 1 mg/1 SA is used in combination with 100 mg/1 GA3. 100 mg/1 GA3+ 1 mg/1 SA and 100 mg/1 GA3+ 100 mg/1 β‐N increase the number of floral buds as compared with 100 mg/1 GA3 alone.
The Water Relations of Pinus sylvestris III. Diurnal and Seasonal Patterns of Water Potential
Authors: HELLKVIST JERK , PARSBY JAN
Published: April 2006

The water potential (ψ) in twigs from four clones of Scots pine (Pinus sylvestris L.) growing in close proximity to each other was measured in a pressure chamber during five selected periods between May 1972 and March 1973. Diurnal and seasonal patterns of ψ are presented in relation to irradiance, air temperature and vapour pressure deficit (VPD) for one cloudy and one clear day in each experimental period. Significant differences in ψ were found amongst most of the clones. Larger amplitudes and earlier day‐time minima in ψ were found during the summer than during the winter. Noon values of ψ of less than −12 bars were regularly found during the summer months.

Plots of ψ against irradiance or VPD during a day, showed marked hysteresis as the result of the simultaneous influence on ψ of several environmental factors. Close linear relations resulted when ψ was plotted against potential evaporation rate (calculated from the Penman‐Monteith formula). The slopes of these regression lines, essentially the flow resistance, showed marked seasonal variations. At both high and low evaporation rates, the clone that grew the fastest had the lowest values of ψ, and the clone that grew the slowest had the highest values of ψ, while the other two clones had intermediate values. Differences in solute potential or in stomatal, plant or soil resistance are discussed as possible explanations of the more or less constant differences between the clones during the year of observations.
Localization and Activity of Naphthylamidases in Germinating Seeds of Scots Pine, Pinus sylvestris
Authors: SALMIA M. AULIKKI , MIKOLA JUHANI J.
Published: April 2006

Extracts prepared from endosperms of germinating seeds of Scots pine, Pinus sylvestris L., rapidly hydrolysed the β‐naphthylamides of L‐phenylalanine and L‐leucine optimally at pH 6.5 and that of L‐arginine at pH 7.7. Disc electrophoresis followed by activity staining showed that the activities were due to two naphthylamidases (aminopeptidases) with different substrate specificities.

Seeds were allowed to germinate at 20°C on agar gel in the dark and the activities on the three substrates were assayed from separated endosperms and seedlings at various stages of germination. The activities in the endosperm of resting seeds were relatively high and they remained unchanged throughout the period of reserve protein mobilization (seedling length up to 50 mm), after which they began to decrease. The activities of the naphthylamidases are rather small compared with those of the two alkaline peptidases of pine, contributing about 17% of the total amino‐peptidase activity in the endosperm of germinating seeds. The total aminopeptidase activity is sufficient to account for the rate of storage protein mobilization during germination.

In the seedlings the naphthylamidase activities (per seedling) increased continuously during germination, and activities per g dry weight were higher than those in the endosperm.
Amelioration of Chilling Injuries in Cucumber Seedlings by Abscisic Acid
Authors: RIKIN ARNON , RICHMOND AMOS E.
Published: April 2006

Exposure of cucumber seedlings (Cucumis sativus L.) to chilling temperature resulted in injuries such as increased leakage of cellular materials, loss of water and wilting. In addition, the development of the seedlings after the exposure to chilling was impaired. Abscisic acid applied to the seedlings prior to chilling significantly ameliorated these injuries.
The Effect of Leaf Water Potential, Leaf Temperature and Light Intensity on Leaf Diffusion Resistance and the Transpiration of Leaves of Malus sylvestris
Authors: WEST D. W. , GAFF D. F.
Published: April 2006

The relationship between leaf resistance to water vapour diffusion and each of the factors leaf water potential, light intensity and leaf temperature was determined for leaves on seedling apple trees (Malus sylvestris Mill. cv. Granny Smith) in the laboratory. Leaf cuticular resistance was also determined and transpiration was measured on attached leaves for a range of conditions.

Leaf resistance was shown to be independent of water potential until potential fell below — 19 bars after which leaf resistance increased rapidly. Exposure of leaves to CO2‐free air extended the range for which resistance was independent of water potential to — 30 bars.

The light requirement for minimum leaf resistance was 10 to 20 W m−2 and at light intensities exceeding these, leaf resistance was unaffected by light intensity.

Optimum leaf temperature for minimum diffusion resistance was 23 ± 2°C. The rate of change measured in leaf resistance in leaves given a sudden change in leaf temperature increased as the magnitude of the temperature change increased. For a sudden change of 1°C in leaf temperature, diffusion resistance changed at a rate of 0.01 s cm−1 min−1 whilst for a 9°C leaf temperature change, diffusion resistance changed at a rate of 0.1 s cm−1 min−1.

Cuticular resistance of these leaves was 125 s cm−1 which is very high compared with resistances for open stomata of 1.5 to 4 s cm−1 and 30 to 35 s cm−1 for stomata closed in the dark.

Transpiration was measured in attached apple leaves enclosed in a leaf chamber and exposed to a range of conditions of leaf temperature and ambient water vapour density. Peak transpiration of approximately 5 × 10−6 g cm−2 s−1 occurred at a vapour density gradient from the leaf to the air of 12 to 14 g m−3 after which transpiration declined due presumably to increased stomatal resistance. Leaves in CO2‐free air attained a peak transpiration of 11 × 10−6 g cm−2 s−1 due to lower values of leaf resistance in CO2 free air. Transpiration then declined in these leaves due to development of an internal leaf resistance (of up to 2 s cm−1). The internal resistance was masked in leaves at normal CO2 concentrations by the increase in stomatal resistance.
Elongation, Solute Loss, Osmotic Potential Changes, and Respiration Rate Changes during the Treatment of Avena Coleoptile Segments with Superoptimal Auxin Concentrations
Authors: RUESINK ALBERT W. , FEEMAN TERESA
Published: April 2006

When treated with 100 μg/ml (0.57 mM) indole‐3‐acetic acid at pH 4.5, Avena sativa coleoptile segments elongate rapidly at first but begin to shrink after a few hours and eventually approach their initial length. Sufficient quantities of potassium and reducing sugars leak into the medium to reflect a significant change in osmotic potential of the tissues due to solute loss. Plasmometric measurements of subepidermal cell osmotic potentials reveal no alterations in that cell layer due to superoptimal auxin treatments: therefore other cells, presumably those of the epidermis, must be responsible for both the obvious loss of segment turgor and most of the solute loss. The relationship of the change in length to change in volume is the same for segments growing in no auxin, optimal auxin, and superoptimal auxin, indicating that cell swelling in other dimensions is not related to the differences in elongation. The respiration rate in superoptimal auxin falls several hours before the growth slows and stops. This result and the observation that auxin must be accumulated by segments to exert a growth inhibition suggest a site of inhibitory auxin action at or inside of the plasma membrane and not just upon the cell wall.
Water Relations of the Hemiparasite Rhinanthus serotinus before and after Attachment
Authors: KLAREN CHRISTINE H. , VAN DE DIJK SIEBREN J.
Published: April 2006

Growth of the hemiparasite Rhinanthus serotinus (Schönh.) Oborny was greatly stimulated after attachment of the parasite to the roots of the host plant, Hordeum vulgare L. Before attachment the hydrostatic pressure in the xylem, determined by the pressure bomb technique, was found to be lower in Rhinanthus than in the host. It increased after the formation of haustoria between host and parasite. Apparently, the water transport to Rhinanthus was facilitated. The hydrostatic pressure remained lower than that of the host, accounting for the flow of water and solutes in the direction of the parasite and indicating that there exists a resistance to water transport in the haustoria. Water and solutes were absorbed by the cells, which increased in size. The turgor pressure of the parasite rose steeply, but the osmotic potential was hardly affected.
The Effect of Soil Water Regimes on Leaf Water Potential, Growth and Development of Soybeans
Authors: ADJE‐TWUM DANIEL C. , SPLITTSTOESSER WALTER E.
Published: April 2006

The growth and development of soybeans (Glycine max L. cv. Amsoy) was studied at soil matric potentials of −0.1 to −1.0 bars. Chlorophyll, photosynthesis, and leaf nitrogen per plant was greatest at −4 bars leaf water potential. Leaf area, number of internodes, plant height and dry weight of vegetative parts declined as leaf water potential decreased from −2 to −19 bars. Nitrogen content and nitrate reductase activity per g fresh weight determined the percentage protein of individual seeds but nitrogen content and nitrate reductase activity per plant determined the amount of total seed protein. The protein synthesized in the seed changed little in amino acid composition with changes in leaf water potential. Leaf water potentials above or below −4 bars decreased yield, total protein and total lipid but plants produced the largest percentage of individual seed protein at −19 bars leaf water potential.
Ferredoxin–NADP+ Reductase from Tsuga canadensis. A Procedure for Isolation and Properties
Authors: RIOV JOSEPH , BROWN GREGORY
Published: April 2006

Activity of ferredoxin‐NADP+ reductase in leaf extracts of eastern hemlock [Tsuga canadensis (L.) Carr.] was relatively low, but could be markedly increased by use of protective agents. The best method employed polyvinylpolypyrrolidone (PVP) in the extraction medium plus removal of phenolic compounds by filtering the extracts through an insoluble PVP (Polyclar AT) column. Further purification of the enzyme was achieved by means of DEAE cellulose chromatography and DEAE Sephadex chromatography. A 94‐fold purification of the enzyme with a total recovery of 43% was obtained.

The eastern hemlock ferredoxin‐NADP+ reductase was characterized by its diaphorase activity, i.e. the transfer of electrons from NADPH to an electron acceptor. 2,6‐dichlorophenol indophenol. The pH optimum for the oxidation of NADPH is between 8.5 and 9.0. The enzyme is highly specific for its electron donor. NADPH, but shows low specificity for electron acceptors. The apparent Michaelis constant values of the enzyme for NADPH. NADH, and 2,6‐dichlorophenol indophenol are 2.4 × 10−5, 5.4 × 10−3, and 4.7 × 10−5M respectively. The molecular weight of the enzyme, as estimated by gel filtration, is about 45,000. The enzyme is inhibited by both organic and inorganic mercurials and certain cations. Comparison of properties of eastern hemlock ferredoxin‐NADP+ reductase and spinach ferredoxin‐NADP+ reductase shows that both enzymes are similar.
Effects of Cadmium on Respiration Rate and Activities of Several Enzymes in Soybean Seedlings
Authors: LEE K. C. , CUNNINGHAM B. A. , PAULSEN G. M. , LIANG G. H. , MOORE R. B.
Published: April 2006

Soybean (Glycine max L. ev. Columbus) seedlings grown in culture solution were treated with cadmium as CdSO4. Final concentrations of cadmium (Cd2+) in the solution were 0, 0.45, 0.90, and 1.35 μM. Soybean leaves, analyzed 10 days after Cd2+ was added to the culture solution, showed increased respiration rate and activities of malate dehydrogenase, acid phosphatase, ribonuclease, deoxyribonuclease, and peroxidase but decreased activity of carbonic anhydrase. Increased activity of hydrolytic enzymes and peroxidase reflects a general senescence response while the carbonic anhydrase decrease is consistent with an antagonism between cadmium and endogenous zinc. Chlorosis, epinasty, abscission of leaves, and decreased growth rate occurred in seedlings treated with 1.35 μM Cd2+.
Effects of Nitrogen, Sucrose, IAA and Kinetin on Explants of Beta vulgaris Grown in vitro
Authors: WELANDER TORKEL
Published: April 2006

Hypocotyl explants of Beta vulgaris L. were grown on defined agar media with different combinations of IAA and kinetin at varying concentrations of nitrogen or sucrose. The cultures were kept in light (18 h a day) at 27°C for 5 weeks. Root initiation and callus growth were recorded and the callus tissue was analysed for N and K.

Root formation was found to increase with increasing nitrogen concentration (from 5 mM to 23.3 mM) in the medium at 10.0 mg/1 of IAA, whereas no stimulation was found at 0.1 mg/1 of IAA. When raising the sucrose level from 20 g/1 to 100 mg/1 at 10.0 mg/1 of IAA and 1.0 mg/1 of kinetin, root initiation was also stimulated. At a lower kinetin and auxin level, however, no increase was recorded.

Callus growth was affected by changes in the nitrogen or sucrose concentration of the culture media. The nitrogen content of the callus tissue increased with rising nitrogen concentration of the media. When raising the sucrose level instead of the nitrogen level, the nitrogen content of the tissue decreased.