bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of growth substances on flowering and sex expression in isolated apical buds of Spinacia oleracea
Authors: ĆULAFIĆ LJUBINKA , NEŠKOVIĆ MIRJANA
Published: April 2006

Apical buds of Spinacia oleracea L. cv. Matador were isolated from 7‐day‐old vegetative seedlings and grown in sterile culture under inductive long, or non‐inductive short photoperiods. Flowering of isolated apices was inducible in long days in approximately 75% of the plants, and in short days by gibberellin treatment (about 40%) or by raising the temperature to 30–32°C (13%). In long days the percentage of flowering was further increased by gibberellin treatment (up to 90%), while it was unaffected by abscisic acid and was strongly decreased by Amo 1618 (55%). In long days the ratio of male to female plants was near 1. The percentage of female plants in long days was increased by gibberellins, and the percentage of male ones decreased by kinetin; as a consequence, the ratio of male to female plants was lowered to about 0.50 in both cases. Abscisic acid and Amo 1618 had the opposite effect, probably because they decreased the flowering in female plants, so that the sex ratio was shifted to 2.6 and 6.8, respectively. Simultaneous treatment with GA3 reversed the effect of abscisic acid on the sex ratio, but the reversal of the shift to maleness induced by Amo 1618 was only partial.

In short days, gibberellins also stimulated the flowering in female plants more than in male. However, when the flowering was induced by higher temperature, most flowering plants were male and kinetin increased their percentage further.

The above results have been discussed in terms of different requirements for flowering in male and female plants.
Preferential distribution of excitation energy into photosystem I of desiccated samples of the lichen Cladonia impexa and the isolated lichen‐alga Trebouxia pyriformis
Authors: SIGFRIDSSON BJORN , OQUIST GUNNAR
Published: April 2006

Abstract The effect of desiccation on distribution of excitation energy between the two photosystems has been studied in the lichen Cladonia impexa Harm., in the green alga Trebouxia pyriformis Archibald, isolated from Cladonia squamosa; and in the non‐lichen green alga Scenedesmus obliquus, strain D3. The method used was to compare the low temperature fluorescence emission of samples equilibrated with air with different humidity prior to freezing in liquid nitrogen.

Desiccation of Cladonia and Trebouxia caused a pronounced increase of the height of the far red fluorescence emission band, F 715, over the short wave bands, F685 and F697; the ratio between the two short wave bands remained essentially constant. Upon rewetting, these species regained normal fluorescence emission properties, indicating that they are desiccation‐tolerant. Scenedesmus, which was used as a desiccation intolerant species, also showed an increase of the far red fluorescence band over the two short wave bands upon desiccation, but the original fluorescence spectrum was not restored upon rewetting.

These results are interpreted as showing that desiccation of tolerant species such as Cladonia and Trebouxia causes a preferential energy distribution into photosystem I. We tentatively believe that desiccation induces conformational changes within the chloroplast thylakoids, thereby controlling distribution of energy between the two photosystems. Furthermore, this change in energy distribution may be of ecological significance as the mechanism by which desiccated lichens or algae avoid photo‐dynamic destruction of the photosynthetic apparatus when photosynthesis is inhibited under dry conditions. By a preferential distribution of absorbed energy into photosystem I, the organisms avoid the formation of strong, harmful oxidants in photosystem II when photosynthesis is inhibited. It is suggested that β‐carotene associated with the far red‐absorbing chlorophyll a fraction of the reaction center antenna of photosystem I is the final sink for excess excitation energy in dry, desiccation‐tolerant lichens and algae.
Photocontrol of seed germination in the hemiparasite Buchnera hispida (Scrophulariaceae)
Authors: NWOKE F. I. O. , OKONKWO S. N. C.
Published: April 2006

Abstract Buchnera hispida, a facultative root parasite of grasses and graminaceous crops, has a light requirement for germination. Studies were carried out on the effects of varying photoperiods with or without preceding dark incubation, on seed germination. Buchnera seeds showed long‐day behaviour, since they germinated at all photoperiods including continuous light, and longer photoperiods were more effective in triggering seed germination than shorter photoperiods. Also, effects of red and far‐red light indicated that the phytochrome system is operative in the light‐induced germination of Buchnera.

Although dark incubation in water before illumination was not absolutely necessary for germination, it caused the seeds to respond more rapidly to light. The longer the time of the dark incubation the more responsive the seeds were to photoperiod except when 15 min light was given. The effectiveness of a preceding dark incubation in making Buchnera seeds sensitive to rapid light action was completely inhibited at 4°C. This is in agreement with the hypothesis that a reaction partner of the far‐red absorbing form of phytochrome is produced during dark incubation of Buchnera seeds. Such an intermediate has also been reported in some positively photoblastic seeds of non‐parasitic flowering plants.
Herbicides which inhibit photosystem II or produce chlorosis and their effect on production and transformation of pigments in etiolated radish seedlings (Raphanus sativus)
Authors: BUSCHMANN CLAUS , GRUMBACH KARL H. , BACH THOMAS J.
Published: April 2006

Abstract The herbicides DCMU, bentazon, amitrole, and SAN 6706 were tested for their ability to influence the carotenoid and pro‐tochlorophyll(ide) composition as well as the protochloro‐phyll(ide) phototransformation and the Shibata shift in dark‐grown radish seedlings (Raphanus sativus L. cv. Saxa Treib). Bentazon enhanced the formation of lutein and carotenes, while SAN 6706 suppressed the biosynthesis of carotenoids. Amitrole led to a reduced accumulation of phototransformable pro‐tochlorophyll(ide). The phototransformation of pro‐tochlorophyll(ide) and the Shibata shift were not affected by any of the tested herbicides, irrespective of the presence or absence of activated phytochrome. From this we conclude that herbicides inhibiting photosystem II or producing chlorosis partly affect, but do not block, carotenoid and chlorophyll biosynthesis in dark‐grown plants. The main herbicide effect becomes visible only after prolonged illumination.
Photosynthesis in cell suspension cultures of the CAM plant Chamaecereus sylvestrii (Cactaceae)
Authors: SEENI S. , GNANAM A.
Published: April 2006

Abstract Photosynthetic properties of cell suspension cultures derived from the callus proliferation of cladophyll explants of Chamaecereus sylvestrii Spegazzini were studied. High content of chlorophyll (105–120 μg/g fresh weight), cyanide sensitive O2 uptake and maximal rates of O2 evolution (100–115 μmol/mg Chl x h) and CO2 fixation (130–150 μmol/mg Chl x h) were some of the properties of the exponential phase cells. Determination of the component reactions, viz. photosystems I and II and photophosphorylation of the chloroplasts isolated from the cells, indicated normal development and functioning of the photosynthetic machinery.

Studies on the enzymatic reactions as well as the determination of the early products of 14CO2 fixation in light in these cells implicated the operation of both autotrophic and non‐auto‐trophic pathways, the latter being less pronounced. The diurnal oscillation of titratable acidity and malate content found in the intact cladophyll tissues was absent in the cultured cells. Evidences for a rapid and continuous drain of carbon from malate into the citrate and isocitrate components of the TCA cycle via pyruvate after decarboxylation, and then into the amino acid pool are presented. The absence of large vacuoles and the rapid turnover of malate are considered to account for the lack of diurnal fluctuation of organic acide in the cell cultures.
The uptake of phosphate by Carex species from oligotrophic to eutrophic swamp habitats
Authors: ATWELL BRIAN J. , VEERKAMP MIRJAM T. , STUIVER BEP (C. E. E.) , KUIPER PIETER J. C.
Published: April 2006

Abstract Phosphate uptake by excised roots of Carex species from a range of oligotrophic to eutrophic swamps was investigated. The range of species from oligotrophic to eutrophic is: C.rostrata Stokes, C.limosa L., C.lasiocarpa Ehrh., C.diandra Schrank, C.hudsonii A.Benn. and C.acutiformis Ehrh. All species showed two phases for Pi uptake in the Pi concentration range of 0.01 – 50 μM. In phase 1, C.rostrata and C.lasiocarpa had relatively high Vmax:s and Km:s, whereas the species from richer areas had intermediate values. The lowest Vmax and Km values were found in C.limosa and C.hudsonii. In phase 2, apart from the high Vmax and Km values found for C.lasiocarpa, the kinetic constants showed little variation, indicating a similar Pi carrier mechanism for all the species. Results on phosphate uptake and leakage are discussed against the phosphate requirement of each species in its specific habitat, and against the literature data of agricultural crops, which generally show a much lower affinity for phosphate uptake.
The effect of kinetin on the level of an indoleacetylaspartic acid like substance in germinating seeds and young plants of Phaseolus vulgaris
Authors: SALEH ADIRUKMI NOOR , HEMBERG TORSTEN
Published: April 2006

Kinetin treatment increased the level of an extractable indoleacetyl conjugate, apparently indoleacetylaspartic acid (IAAsp) in germinating seeds and young plants of Phaseolus vulgaris L. cv. Alabaster. The level of this substance in extracts of treated seeds was always higher than that from water treated seeds irrespective of whether the seeds had been extracted 24, 48 or 72 h after the beginning of the treatment. In all parts of young bean plants treated with kinetin there was more of the substance than in the corresponding parts of water treated plants.
Chromosomal proteins of conifers
Authors: PITEL J. A. , DURZAN D. J.
Published: April 2006

During imbibition and germination of jack pine seeds, the composition of the total extractable chromatin varied. Relative to DNA, the histone levels decreased as the nonhistone chromosomal proteins (NHCP) increased. New chromosomal proteins were synthesized after 2 days of imbibition as judged by recovery of 14C‐amino acids from the major protein fractions. Phosphorylation of histones from 32P‐phosphoric acid was detected before the incorporation of 14C‐amino acids. In the seed the synthesis and relative changes of chromatin coincided with a fall in total soluble protein and free arginine N. By contrast, adenylate energy charge, free glutamine N and in vitro template activity of chromatin increased during chromatin protein synthesis.

When seeds had germinated for 4 days after the start of imbibition more radioactivity, derived from free 14C‐amino acids, was recovered from the NHCP than from the histones. The percentage amino acid composition of most histone fractions remained stable, whereas the composition of NHCP changed more with time. The phosphorylation of NHCP was 8‐ to 41‐fold greater than that of the histones. Phosphorylation of histone H4 was not detected at any stage of germination. Correlations between recovery of radioactivity (32P and 14C) from chromosomal proteins and higher adenylate energy charge were positive.
The influence of the extraction procedure on yield of indole‐3‐acetic acid in plant extracts
Authors: HEMBERG TORSTEN , TILLBERG ELISABETH
Published: April 2006

Different types of plant material, including both dry and swollen maize kernels, swollen bean seeds, bean seedlings and dry rose seeds, were extracted by different methods and the yield of IAA was determined with the indolo‐α‐pyrone method.

Extraction of dry maize kernels during short time experiments, varying from 3 to 24 h, gave the highest IAA yield when methanol was the extractant and a significant lower yield when diethyl ether or dichloromethane were used. The duration of the extraction period increased the yield with all the extractants. Progressive extractions for several days or weeks had little effect on the yield when 100% acetone was used in contrast to methanol and ether as extractants, which increased the yield during prolonged extraction. Extractions of tissue treated to 100°C for 1 h contradicted the hypothesis that IAA is enzymatically liberated during ether extraction. Water in the extractant solvents increased the yields. This was most pronounced when aqueous acetone was used instead of 100% acetone. Increased extraction temperature augmented the IAA yields.

The yield of IAA from other types of tissue extracted with methanol for periods of 3 or 24 h was, however, independent of the duration of the extraction time. This indicates that some tissues contain less not easily extractable IAA than dry maize kernels. The terms “free” and “bound” IAA are discussed; they should be replaced by “easily extractable” and “not easily extractable” IAA.

The results also show that IPyA in vitro can partly be converted to IAA during extraction and fractionation.
Reassociation of cytoplasmic ribosomal subunits of barley and its virescens mutant to form active hybrids
Authors: KOUNDAL KIRPA R. , COHEN ABE S. , ZALIK SAUL
Published: April 2006

Polyphenylalamine synthesis by cytoplasmic ribosomes of Gateway barley (Hordeum vulgare) and its virescens single gene nuclear mutant was compared. The cytoplasmic 80S ribosomes were isolated from unimbibed embryo material and the ribosomes were dissociated into their component 60S and 40S subunits by centrifugation through sucrose gradients containing high KCl‐to‐MgCl2 buffer. These separated subunits could be reassociated by resuspension in buffer having about equimolar concentrations of MgCl2 and KCl. Both homologous and heterologous combinations of the subunits reassociated to give monomeric 80S ribosomes, and the derived monomers as well as various combinations of the individual subunits showed equivalent activity in an in vitro system for poly (U)‐directed polyphenylalanine synthesis.
Growth rate and phosphate utilization of some Carex species from a range of oligotrophic to eutrophic swamp habitats
Authors: VEERKAMP MIRJAM T. , CORRÉ WIM J. , ATWELL BRIAN J. , KUIPER PIETER J. C.
Published: April 2006

In a growth experiment at phosphate levels varying between 0,0005 and 0.1 mM phosphate, relative growth rates and other growth parameters were determined in Carex species (C. rostrata Stokes, C. limosa L., C. lasiocarpa Ehrh., C. diandra Schrank, and C. acutiformis Ehrh., listed in order of increasing nutrient availability of their natural habitats). In all species, more efficient utilization of the phosphate was observed with decreasing phosphate levels, together with reduced fresh shoot ratio. In addition, each species shows characteristics which may help it to grow under low phosphate conditions: relatively high phosphate level in the plant (C. rostrata), a low fresh shoot ratio (C. limosa) and regulation of uptake and translocation of phosphate in such a way that relative growth rate during the first two weeks is maintained or even increased for a longer period (C. rostrata, C. limosa, and C. diandra). In the studied Carex species, the contribution of fresh shoot ratio to relative growth rate is much larger than that of net assimilation rate. C. acutiformis, a species of eutrophic areas, had the highest relative growth rate.
Factors affecting 14C‐sucrose uptake by single‐node explants of rose flower stems
Authors: JACOBS GERARD , ZIELIN NAFTALY , HALEVY ABRAHAM H.
Published: April 2006

Single node explants of ‘Baccara’ rose were fed through the basal cut surface with 14C‐sucrose in agar. Accumulation of 14C‐metabolites by buds is a steady process, while a quick uptake occurs in the stem piece during the initial stage of incubation suggesting a passive uptake at this stage. The uppermost 5‐leaflet node buds had an initially higher 14C‐uptake than the lowest bud. This difference disappeared after 2–3 days when growth started in both buds. Light enhanced uptake of 14C‐sucrose by both stem pieces and buds. Accumulation of 14C‐metabolites by buds was in direct relationship to buds deviation from the direction of gravity. This phenomenon was not evident in the stem part of the explant.
Ultrastructure and movements of cell structures in normal pea and an ageotropic mutant
Authors: OLSEN GUNN MARI , IVERSEN TOR‐HENNING
Published: April 2006

The pea mutant (Pisum sativum ageotropum) and the normal pea (P. sativum cv. Sabel) were compared in order to see if there were any differences in root anatomy or submorphology which could explain the presumed ageotropic behaviour of the mutant. In both types the root cap consists of a central core (columella) distinct from the peripheral part. The core contains five to six rows of columella cells, each consisting of 10 to 16 storeys of statocytes. The ultrastructure of the columella cells in the two types is very similar; the main difference is confined to the distribution of rough endoplasmic reticulum (ER), which in the mutant statocytes is evenly distributed throughout the cell, while in the normal pea statocytes it is mainly concentrated in the distal part at the “floor” of the cell.

Using light micrographs, the movement of amyloplasts and nuclei have been followed in detail during a 40 min inversion period. The pattern of movement of the amyloplasts is apparently identical in the two types and the distances moved during the inversion period are 39 μm and 44 μm in the normal and mutant statocytes, respectively. The nucleus has not been observed to move in normal pea; a slight rearrangement of the nucleus position can be observed during the period 30 to 40 min after the start of inversion of the mutant.

Based on magnified electron micrographs of the statocytes a morphometrical analysis was made of five cell structures – amyloplasts, nuclei, mitochondria, vacuoles and ER – which appeared to be freely movable or redistributable under the influence of the gravitational force.
Growth and zinc accumulation in spinach
Authors: DESMET G. M. , DIRKSE W. G.
Published: April 2006

Zinc accumulation in spinach (Spinacea oleracea L. cv. Verbeterd Breedblad), especially in the leaves, has been studied in plants grown on nutrient solutions. The extent of accumulation depends on, but is not proportional to the external zinc supply. Zinc uptake by water flow does not account for the concentrations observed in the various plant parts. The relative accumulation rate is related to the relative growth rate, but depends also on leaf position and leaf age.

The data suggest that the midribs act as sinks for the nutrient solution, whilst the leaf blades in turn act as sinks for the midribs. We suggest that strong binding of zinc occurs to specific organic compounds in the cell, thus, diminishing the concentration of the free zinc ions in the biological tissue.
15N2 fixation, H2 evolution and C2H2 reduction relationships in Phaseolus vulgaris
Authors: SAITO S. M. T. , MATSUI E. , SALATI E.
Published: April 2006

In a study of N2 fixation in nodules of beans (Phaseolus vulgaris L.) cv. Venezuela‐350 of different ages and kept under controlled light and temperature conditions, three parameters ‐ 15N2 fixation, C2H2 reduction and H2 evolution—were measured.

C2H2 reduction was positively related to the N fixed. A standardization of sampling is necessary to keep experimental errors to a minimum. To decrease the variation between replications, the nodules should be carefully incubated (adequate time and temperature), and the samples for chromatography should also be carefully stored. No significant difference was found in C2H2 reduction in the systems studied ‐ nodulated roots, disturbed whole plants and intact plants—during the first hour of measurement.

H2 evolution was detected in nodules over 20 days of age and was positively related to N2 fixation and C2H2 reduction. This measurement was essential to account for the equilibrium between the three parameters in the electron balance ratio. Under phytotron conditions, maximum H2 evolution occurred 20–30 days after planting.

Nodulated roots from different plants were used to determine the N2 fixed and C2H2 reduction, and on average the ratios C2H2:N2 varied between 7.3 and 8.3 for all ages. In vivo C2H4/(3N2+ H2) electron balance values were over 1, varying from 1.32 to 1.43. These data suggest that overestimation of actual N2 fixation might be occurring when using the C2H2 reduction technique, even if taking account for H2 evolution. In this case, this method should be used with great care to avoid an overestimation of on average 32‐43% of the actual value. Variation was smaller between the measures of the three parameters when younger nodules were used.
Respiratory pathways in aged soybean seeds
Authors: LEOPOLD A. C. , MUSGRAVE MARY E.
Published: April 2006

Respiratory activities in soybean seeds (Glvcine max (L.) Merr. cv. Chippewa 64) have been examined in the first minutes after water imbibition and after three hours of imbibition, using either particles or intact axes. Cyanide and azide were utilized as inhibitors of the cytochrome oxidase pathway of respiration, and SHAM inhibitions were interpreted as effects on the alternative pathway, since in unaged axes inhibitions by SHAM were obtained only when respiratory activity had either been restricted with inhibitors of the cytochrome oxidase pathway or expanded by an uncoupler (CCCP). From the experiments with these inhibitors, it is suggested that unaged seeds utilize both respiration pathways in the cotyledon but only the cytochrome pathway in the axis. Accelerated aging causes a marked deterioration of respiration, especially that through the cytochrome pathway, and there is an associated engagement of the alternative pathway in the seed axis. It is suggested that the lowering of respiratory activity and the shift in respiratory pathways may play a major role in the decline of germinability and vigor.
Influence ?une alimentation continue avec une solution glucosée sur ľévolution des glucides et des protéines dans les divers organes de la rose coupée (Rosa hybrida cv. Carina)
Authors: PAULIN ANDRÉ
Published: April 2006

Influence of continuous supply with a solution of glucose on the changes in the content of soluble sugars and proteins in various organs of the cut rose (Rosa hybrida cv. Carina).

Exogenous glucose continuously supplied to the cut rose is immediately converted into saccharose in the stem tissues. This saccharose migrates to the flower, where it is immediately hyd‐rolysed, and to the leaves where its hydrolysis occurs more slowly. The reducing sugars resulting from the hydrolysis of saccharose in the flower and, therefore, possibly from the hydrolysis of saccharose in leaves, induce a large accumulation of hexoses (glucose and fructose) in the flower. The protein content does not depend on the level of reducing sugars in the flower.
Prevention of auxin‐induced epinasty by α‐aminooxyacetic acid
Authors: AMRHEIN NIKOLAUS , SCHNEEBECK DIRK
Published: April 2006

Elhylene production and epinastic growth of leaf petioles of tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants sprayed with 0.1 mM naphthyl‐1‐acetic acid were suppressed when 1 mMα‐aminooxyacetic acid (AOA) was simultaneously sprayed on the plants. AOA had no effect on ethylene evolution and epinastic growth resulting from the application of 5 mM 1‐aminocyclopropane‐1‐carboxylic acid, the immediate precursor of ethylene.
Effects of lithium and potassium on recovery of solute uptake capacity of Acer pseudoplatanus cells after gas‐shock
Authors: THELLIER MICHEL , THOIRON BERNARD , THOIRON ARLETTE , GUIEL JEANNE LE , LÜTTGE ULRICH
Published: April 2006

At concentrations of 10‐−3M, Li+ inhibits the recovery of solute uptake capacity of Acer pseudoplatanus L. cell suspension cultures after gas‐shock (i.e. after rapid exchange of the atmosphere in the culture flasks for ambient air). It also reduces solute uptake capacity of cells having already attained high rates of uptake during recovery from gas‐shock. The effects of Li+ are much greater in cells which have been cultivated in 7 mM K+ solution than in cells cultivated with higher K+ levels (19 mM). Increasing K+ concentration during recovery reverses the effect of 10–3M Li+ and, with sufficiently high concentrations of K+ (≥ 10‐−2M) during recovery, the solute uptake capacity of the fully recovered cells can even become greater than that of the control, at least for the low values of substrate concentration (here sulphate 10‐−5M). Since Li+ does not affect the time course of solute uptake measured over 15–20 min, it is thought that it interacts with the synthesis and turnover of the solute uptake machinery of the Acer pseudoplatanus cells. Thermodynamic analysis of the flux data also supports the hypothesis that Li+ inhibits the biosynthesis of specific sites of solute permeation, but it does not rule out the possibility that K+ interferes rather on the forces acting on the transport of the considered solutes than on the catalytic structures of permeation.
Activité antitranspirante d'analogues de l'acide abscissique
Authors: Carbonnier J. , Giraud M. , Hubac C. , Molho D. , Valla A.
Published: April 2006

40 aromatic and chlorocyclohexenic structural analogues of abscisic acid were synthesized stereospecifically, and inhibition of transpiration was investigated following two experimental procedures (cut barley leaves and water stressed cotton plants). Structure‐activity relationships are discussed. – Two chlorosubstituted cyclohexenic compounds are the most active; their inhibition of transpiration can be compared to that of abscisic acid.
Photocontrol of spore germination in the fern Thelypteris kunthii
Authors: Huckaby Clark S. , Raghavan V.
Published: April 2006

The light requirement for germination in spores of the fern Thelypteris kunthii (Desv.) Morton was fully satisfied by a long period of continuous red light or partially by intermittent, short periods of red light. Red light‐potentiated spore germination was inhibited by brief far‐red light irradiation, indicating phytochrome involvement. Repeated exposure of spores to prolonged red and short far‐red irradiations, or exposure of red‐potentiated spores to far‐red light after an extended period in darkness, led to their escape from inhibition of germination by far‐red light. Prolonged irradiation of spores with blue light before or after red light treatment partially antagonized the effect of red light.
Kinetic analysis of root growth and georeaction
Authors: Baehler William , Pilet Paul‐Emile
Published: April 2006

The kinetics of growth and georeaction of horizontal or vertical maize (cv. ORLA 264) apical root segments were analysed. Elongation and curvature data were fitted to a mathematical function and the effect of both light and decapitation reported. Elongation of horizontal segments was found to be more sensitive to light than to decapitation. A light treatment or the decapitation presented several effects on the shape of the growth curves. Growth of vertical segments was affected much more by decapitation than by light treatment. The shape of the curves was clearly different for decapitated and intact segments.

Curvature is affected both by light and decapitation but the shape of the bending curves is modified principally by decapitation.

Under the present conditions used, growth and georeaction of root segments do not seem to be strictly correlated.
Promotion of Pylaisiella selwynii growth and gametophore formation by octopine and cytokinin
Authors: Spiess Luretta D. , Lippincott Barbara B. , Lippincott James A.
Published: April 2006

Growth, branching and gametophore formation by protonema developing from spores of the moss Pylaisiella selwynii were promoted by octopine, an unusual amino acid found in crown gall tumors. Cytokinin (0.01 μM) in combination with octopine (0.1 μM to 1 mM) increased the number of gametophores formed and decreased the time required for their development. The combined effect of these two compounds was similar to that obtained with virulent agrobacteria. At higher cytokinin concentrations, protonemal buds formed abnormal masses of cells rather than normal gametophores. Common amino acids and auxins, alone or in combination with cytokinin, had relatively little effect on the development of the moss.
Cellular changes during boron‐deficient culture of the diatom Cylindrotheca fusiformis
Authors: Smyth Douglas A. , Dugger W. M.
Published: April 2006

The effects of boron‐deficient culture were studied on the unicellular diatom. Cylindrotheca fusiformis Reimann and Lewin. After 24 to 30 h, cell division was almost completely inhibited in boron‐deficient cultures. By 48 h of culture, boron‐deficient diatoms had approximately twice the modal cell volume of control cells, and at least twice the amount of organic constituents such as protein (2.0x), insoluble carbohydrate (2.4x), total phenols (2.6x), and chlorophyll at (2.1x). Boron deficiency led to irreversible damage after this time.

Dark respiration was 1 nmol O2/min × 106 cells for both control and boron‐deficient diatoms prior to 40 h of culture. By 48 h, the respiratory rate of boron‐deficient diatoms was double that of controls. The proportion of 14C‐glucose metabolized by the pentose phosphate pathway was similar in both control and boron‐deficient diatoms after 24 and 48 h of culture. After 24 h, the in vitro activity of glucose‐6‐phosphate dehydrogenase was similar in both control and boron‐deficient cells, although the pool size of its substrate, glucose‐6‐phosphate, was 26% greater in boron‐deficient cells. The cellular amount of glucose‐6‐phosphate dehydrogenase continued to increase once mitosis was arrested in boron‐deficient diatoms. Boric acid (1 mM) inhibited 6‐phosphogluconate dehydrogenase by 18% in diatom homogenates.

During the early stages of boron deficiency, the uptake of silicate, nitrate, and phosphate, and the in vitro activity of β‐glucosidase were similar to control diatoms. After cell division was inhibited, boron‐deficient diatoms accumulated more nitrate and phosphate, and retained a higher level of β‐glucosidase than control cells.
The effect of wind and shaking on the water relations of Pinus contorta
Authors: Rees D. J. , Grace J.
Published: April 2006

It is usually suggested that the effects of wind on plant growth and development are caused by water stress. The purpose of the work reported in this paper is to examine this suggestion by a series of experiments in a controlled environment wind tunnel. Cuticular conductance of Pinus contorta subjected to low and high wind‐speeds were determined by weighing detached needles on a microbalance. Although the needles collided with each other at the high wind‐speed, there was no effect on cuticular conductance, unlike results obtained elsewhere with broader‐leaved plants. The transpiration rates and needle conductances of whole plants were unaffected by exposure to wind or a gentle shaking treatment. Water potentials and pressure‐volume curves were determined on individual needles of Pinus contorta. Wind and shaking had no effect on total, solute, or pressure potentials, or in any of the parameters describing the pressure‐volume curves. It is concluded that the effects of these treatments on growth of Pinus contorta, reported in previous papers, are unlikely to be caused by tissue water stress.
Chloroplast‐released inhibitor of phenylalanine ammonia‐lyase from barley (Hordeum vulgare) seedlings
Authors: Podstolski Andrzej
Published: April 2006

Isolated chloroplasts of barley seedlings (Hordeum vulgare L.) when kept in light, released a soluble, thermostable factor that inhibited phenylalanine ammonia‐lyase (PAL) in vitro. Highest inhibition was found when chloroplasts were suspended in PAL‐containing extract and kept in light. Efficiency of PAL activity inhibition did not depend greatly on the type of medium used for chloroplast isolation, nor on the composition of buffer in which the enzymatic activity was measured. It is proposed that in green tissues chloroplasts may participate in regulation of cytoplasmic PAL activity.
Nitrilase activity in clubroot diseased plants
Authors: Rausch Thomas , Butcher Dennis N. , Hilgenberg Willy
Published: April 2006

Nitrilase activity was detected in desalted extracts of leaves, hypocotyls and roots of swede (Brassica napus) but was considerably higher in leaves than in roots. After inoculation with Plasmodiophora brassicae infected roots and hypocotyls showed an increase in nitrilase activity beginning at the early stages of club development before total protein increased significantly. Enzyme activity of infected tissue was partially purified by DEAE ion exchange chromatography and compared to the enzyme extracted from non infected seedlings. It appears that the increase in nitrilase activity is due to an increase of the plant enzyme which is initially present with lower activity. Km values for the artificial substrate 3‐cyanopyridine and for indole‐3‐acetonitrile were 2.1 × 10−3 M and 6.2 × 10−4M, respectively. The role of nitrilase activity for IAA biosynthesis is discussed.
Auxin‐induced changes in the cell wall structure: Changes in the sugar compositions, intrinsic viscosity and molecular weight distributions of matrix polysaccharides of the epicotyl cell wall of Vigna angularis
Authors: Nishitani Kazuhiko , Masuda Yoshio
Published: April 2006

Rapid effects of indole‐3‐acetic acid (IAA) on the mechanical properties of cell wall, and sugar compositions, intrinsic viscosity and molecular weight distribution of cell wall polysaccharides were investigated with excised epicotyl segments of Vigna angularis Ohwi et Ohashi cv. Takara.

IAA caused cell wall loosening as studied by stress‐relaxation analysis within 15 min after the IAA application.

IAA stimulated the decrease in the content of arabinose and galactose in the hemicellulose 1 h after its application. The amounts of other component sugars in the cell wall polysaccharides remained constant during the IAA‐induced segment growth.

The intrinsic viscocity of the pectin increased as early as 30 min after the IAA application. This effect was not prevented when elongation growth of the segment was osmotically suppressed by 0.15 M mannitol.

Gel permeation chromatography of the pectin on a Sepharose 4 B column demonstrated that IAA caused increase in the mass‐average molecular weight of the pectin. Analysis of the sugar compositions of the pectin eluted from the Sepharose 4 B column indicated that IAA increased the molecular weight of the polysaccharides composed of uronic acid, galactose, rhamnose and arabinose. This effect became apparent within 30 min after the IAA application. Furthermore, IAA increased the molecular weight of the pectin when elongation growth of the epicotyl segments was osmotically suppressed by 0.15 M mannitol.

Hemicellulose of the cell wall chromatographed on a Sepharose CL‐4 B column. Analysis of the neutral sugar compositions and the iodine staining property (specific for xyloglucans) of the polysaccharide solution eluted from the column indicated that the hemicellulose consisted of xyloglucans, arabinogalactans and polysaccharides composed of xylose and/or mannose. IAA caused a decrease in the arabinogalactan content and depolymerization of xyloglucans. These IAA effects became apparent within 30 min after the IAA application. These changes occurred even when elongation growth of the epicotyl segments was osmotically suppressed by 0.15 M mannitol.

Polymerization of the pectin, degradation of arabinogalactans and depolymerization of xyloglucans appear to be involved in the mechanism by which IAA induces cell wall loosening and therefore extension growth of cells.
High temperature effects on RuBP carboxylase and carbonic anhydrase activity in two tomato cultivars
Authors: Markus Varda , Lurie Susan , Bravdo B. , Stevens M. A. , Rudich J.
Published: April 2006

The effects of temperature on ribulose bisphosphate carboxylase activity were studied in two tomato (Lycopersicon esculentum Mill.) cultivars which differed in sensitivity to high temperatures. The heat tolerant cultivar, Saladette, had a smaller reduction in photosynthesis and a smaller increase in mesophyll resistance then the sensitive cultivar Roma VF, after 24 h at 35 to 40°C. One hour in vitro treatments at 50°C decreased the activity of ribulose bisphosphate carboxylase extracted from Roma VF by 75%, while Saladette was not affected. Heat stress to the entire plant caused greater inhibition of ribulose bisphosphate carboxylase in the heat sensitive cultivar. Ribulose bisphosphate carboxylase activity in both cultivars decreased with heat treatment but recovered under normal temperatures. Ribulose bisphosphate oxygenase activity decreased similarly in both cultivars under 37/18°C day/night temperatures, which resulted in an apparent change in the relative carboxylase/oxygenase activity of the two cultivars. Carbonic anhydrase activity was slightly greater in Saladette than in Roma VF but no significant decrease in activity was observed in plants exposed to high temperatures.
Membrane and ion transport properties in cereals under acidic and alkaline stress
Authors: Erdei László , Bérczi Alajos , Zsoldos Ferenc
Published: April 2006

The lipid composition of roots of rice (Oryza sativa L. cv. Dunghan Shali) and wheat (Triticum aestivum L. cv. GK Szeged) grown at acidic, neutral or alkaline pH were investigated. Wheat maintained stable total lipid, phospholipid and galactolipid levels at extreme pH, whereas in rice the galactolipid level increased with increasing pH of the growth medium. Spectroscopically, wheat lipids showed alterations at alkaline pH, whereas rice lipids did not. Surface potential measurements on lipid monomolecular layers revealed no significant qualitative differences in charged lipids between the two species. The results are discussed in terms of adaptation to extreme pH.
Is peroxidase involved in ethylene biosynthesis?
Authors: Macháčková Ivana , Zmrhal Zdeněk
Published: April 2006

Wheat (Triticum aestivum L. cv. Jubilar) coleoptile segments convert 1‐aminocyclopropane‐1‐carboxylic acid (ACC) to ethylene. This process is totally inhibited by nitrogen atmosphere and severely inhibited by free radical scavengers (sodium benzoate, ferulic acid), inhibitors of reactive ‐SH groups (p‐chlormercuribenzoate, iodoacetate), CoCl2 and EDTA. Indole‐3‐acetic acid, aminoethoxyvinyl glycine, cycloheximide, actinomycin D, pyridoxal phosphate and NADH have no effect on ACC conversion to ethylene. Some in vivo characteristics of this conversion suggest that it could be catalyzed by peroxidase. However, isoperoxidase B1 isolated from wheat seedlings was not able to catalyze in vitro conversion of ACC to ethylene under a wide range of reaction conditions. Therefore, it is concluded that peroxidase is not directly involved in ethylene biosynthesis.
Evidence against an intermediary role of abscisic acid in stomatal closure induced by phenylmercuric acetate and faresol
Authors: Schult Sabine , Dörffling Karl
Published: April 2006

The hypothesis was tested that stomatal closure induced by the antitranspirants phenylmercuric acetate and farnesol is mediated by an increase in abscisic acid content. Isolated leaves of Spinacia oleracea L. cv. Müma, Tradescantia X andersoniana Ludw. et Rohw. and Commelina communis L. were incubated in solutions of phenylmercuric acetate (10−3M) and of farnesol (2 × 10−3M). In all three species, a reduction in stomatal aperture was observed. The extent and velocity of the reaction differed between the species and also between the two compounds applied. The abscisic acid content of the leaves was determined after stomatal closure had been achieved. No significant increase in abscisic acid level was found in treated leaves of Spinacia and Commelina. In Tradescantia, on the contrary, a reduction to about 50% was observed after 120 min treatment. Visible damage of the treated leaves and membrane alterations observable by electron microscopy occurred, especially after treatment with farnesol. These changes in membrane structure suggest a connection with the reduction in stomatal aperture.
Hormonal regulation of the leaf blade movement of Drosera capensis
Authors: Bopp Martin , Weber Inge
Published: April 2006

Several Drosera species show a bending of the leaf blade as a slow reaction to a prey. In Drosera capensis L. this bending is enhanced by a simultaneous application of IAA either to the prey or to the leaf tip, and IAA alone can induce a curvature of the leaf. This curvature is always to the upper side of the leaf independent of the side of IAA application. PCIB (1 mM), and TIBA (0.1 mM) inhibit the bending reversibly. The inhibition by ABA (1 mM) is not reversible. A TIBA barrier between the prey and the tip of the leaf reduces the bending reaction, whereas application of TIBA to the basal part of the leaf has no effect. In the former case 35% of the leaves showed a strong bending just on the apical side of the TIBA barrier. It is concluded that the bending is a consequence of an internal auxin stream from the tip of the leaf to the bending point, induced by the prey.
Root surface phosphatase activity in ecotypes of Aegilops peregrina
Authors: Silberbush Moshe , Shomer‐Ilan Adiva , Waisel Yoav
Published: April 2006

The relationships between root surface phosphatase activity and the edaphic factors of their native habitats were investigated in four ecotypes of Aegilops peregrina (Hack.) Maire et Weil. In one set of experiments plants were grown in phosphate‐deficient nutrient solution cultures (5 μM) with three pH values: 5.5, 6.5 and 7.5. In a second series, plants were grown in both P‐poor and P‐rich soils.

Results showed an optimal activity of the commonly‐described root surface acid phosphatase of pH 4.5–5.0 in the ecotypes Meron (a P‐poor montmorillonitic, typical mediterranean Terra‐Rossa soil) and Har‐Hurshan (a P‐rich calcareous soil). However, in the ecotypes Malkiya (a P‐rich kaolinitic Terra‐Rossa) and Bet‐Guvrin (a P‐rich calcareous soil) the optimal activity of the phosphatase occurred at pH 6.0. The pH level of the growth solution had no effect on the pH of optimal activity of the phosphatase in the ecotypes Malkiya and Bet‐Guvrin, but it somewhat affected their level of activity.

Phosphatase activity was stimulated when plant roots were grown in a P‐poor soil, as compared to the activity of those which were grown in a P‐rich soil. Plants of the Malkiya ecotype exhibited the strongest activation of phosphatase as compared to the other three ecotypes. It seems that ecotypes which have evolved in P‐rich soils may regulate their root surface phosphatase activity better than those which have evolved in P‐poor soils.
Wall‐protein antibodies as inhibitors of growth and of autolytic reactions of isolated cell wall
Authors: Huber Donald J. , Nevins Donald J.
Published: April 2006

Antiserum raised against protein prepared from corn (Zea mays L. hybrid B73 X Mo17) seedling cell wall exhibits antigrowth activity and inhibits autolytic reactions of isolated cell wall. The growth of corn coleoptile segments pretreated in wall‐protein antiserum was inhibited 35% compared to tissue which had been exposed to normal serum. Since the cuticle constituted a barrier to the entry of serum protein the coleoptile surface was abraded prior to exposure to the serum. Growth inhibition observed in nonabraded sections (8 to 10%) was apparently the result of the entry of serum protein via the cut ends of the tissue. Subsections recut from the central region of antiserum‐treated, nonabraded coleoptiles responded normally in growth experiments. Antiserum brought in contact with isolated cell wall prior to its use with intact coleoptiles was less effective as a growth inhibitor, which suggested that the antibodies which impede growth responses bind to cell wall.

Wall‐protein antiserum also strongly inhibited autolytic reactions of isolated cell wall. Wall treated in normal serum or buffer liberated sugars at a rate of 8.6 μg‐ (mg wall dry‐weight)−1·h−1 while antiserum‐treated wall autolyzed at a rate of 2.6 μg·mg−1·h−1 representing a 70% reduction in autolytic potential. After 24 h yields from antiserum‐treated wall were 50% lower than yields obtained from control wall. The antiserum had no effect on the molecular‐weight distribution of the autolytically‐liberated products, and direct assays of wall‐bound and solubilized endo‐ and exo‐β‐d‐glucanases involved in autolytic reactions demonstrated no significant impairment of their catalytic activity. However, the addition to antiserum‐treated wall of a wall‐protein preparation containing autolytic enzymes resulted in a significant enhancement (132%) in autolytic potential. The evidence suggests that enzyme mobility may be critical in the autolytic hydrolytsis of plant cell wall.
La glutamine synthètase du Suaeda maritima. Action in vivo et in vitro du NaCl
Authors: Boucaud J. , Billard J. P.
Published: April 2006

The glutamine synthetase of Suaeda maritima. In vivo and in vitro action of NaCl Glutamine synthetase (GS; EC 6.3.1.2) was isolated and characterized from roots and aerial parts of the halophyte Suaeda maritima (L.) Dum. var. macrocarpa Moq. Km values of GS were identical in both types of organ and unchanged by the salinity in the medium. Addition of NaCl in the culturing solution increased the specific activity of the enzyme especially in the aerial parts, where GS is more abundant. This increase was all the more pronounced if the plant‐salt contact period was extended (between 21 and 45 days). In vitro the addition of 0 to 500 mM of salt did not affect the activity of GS at satured substrate concentrations. At low glutamate concentrations in combination with 300 mM NaCl or more, a slight competitive inhibition was observed, never over 18%. – The remarkable insensibility of GS to salinity in vitro and the stimulating effect of NaCl in vivo on the synthesis of the leaf enzyme indicates that GS plays a fundamental part in the assimilation of NH4+ in the halophyte Suaeda maritima var. macrocarpa.
Effects of intermittent exposure to high atmospheric CO2 on vegetative growth in soybean
Authors: Clough J. M. , Peet M. M.
Published: April 2006

Short‐term exposure to high CO2 increases rates of photosynthesis and growth in soybeans, but with prolonged high CO2 exposure, these high rates are sometimes not maintained. Growth of soybean (Glycine max (L.) Merrill cv. Fiskeby V) seedlings kept for 25 days at atmospheres of 350 or 1000 μ/l CO2 was compared with growth of plants given 2, 4 or 6 day alternating exposure to high and low CO2 levels (13 days of total exposure to each level). Final dry weight of plants increased with number of days in high CO2 but leaf areas were not greatly affected. Thus dry weight gains per unit leaf area (net assimilation rates) were higher in high CO2 than in low CO2 throughout the entire period of the experiment and the pattern of exposure to high CO2 did not affect the rate of dry weight gain in high CO2.
Adventitious rooting in hypocotyls of sunflower (Helianthus annuus) seedlings
Authors: Fabijan Dorothy , Yeung Edward , Mukherjee Ilibanta , Reid David M.
Published: April 2006

Removal of the main root system of sunflower (Helianthus annuus) initiates adventitious root development on the lower portion of the hypocotyl. The first cytological changes (enlarged nuclei in the interfascicular parenchymatous cells adjacent to the phloem and some cell divisions) are observed 24 h after root excision. On the basis of experiments in which (a) roots, apical buds and various amounts of cotyledonary tissue were removed, (b) cuttings were subjected to various light regimes, (c) benzyladenine oas applied to cotyledons to create an artificial sink, it was concluded that the roots normally produce factors inhibiting to adventitious rooting and might be a sink for stimulatory substances produced in the shoots. The cotyledons seem to be the major source of these stimulators. Application of aqueous and ethanolic extracts of cotyledons and hypocotyls to cuttings promoted adventitious rooting.