bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism
Authors: Libbert Eike , Manteuffel Renate
Published: April 2006

More “diffusible” auxin is received from nonsterile than from sterile corn coleoptile tips. An artificial reinfection of sterile coleoptiles with epiphytic, IAA‐producing bacteria strains does, a superinfection of nonsterile coleoptiles does not increase the auxin amount. The difference between sterile and nonsterile tips persists if diffusion from the coleoptile surface is excluded by covering the surface with a paraffin layer. The greater the distance from the apex, the higher becomes the superiority of nonsterile tips. An artificial bacterial contamination of the contact face between tip and receiver agar block, or addition of glucose and tryptophan to the agar block, do not influence the received auxin amount. Consequently the additional, bacteria‐produced auxin delivered by the nonsterile tip is not produced at the cut surface or in the agar but is present in the tissues of the coleoptile tip.
Seasonal Changes in Auxin Effects on Rooting of Stem Cuttings of Populus nigra and its Relationship with Mobilization of Starch
Authors: Nanda K. K. , Anand V. K.
Published: April 2006

Stem cuttings of Populus nigra were treated with 10 and 100 mg/1 each of IAA., IBA, 2,4‐D and NAA at one month intervals and observations were recorded for the morphophysiological status of the branches, their starch content and their rooting response. — The first phase characterized by delayed, short and scarce roots and the high starch content of cuttings coincided with the onset of winter dormancy in November lasting through February. It was followed by a phase of vigorous rooting and low starch content of cuttings coinciding with the renovation of growth activity in February lasting through October, except in April and May when rooting was more or less completely nullified. — The poor rooting in winter was caused by low activity of hydrolyzing enzymes not mobilizing starch into soluble sugars; and profuse rooting during active growth period by high activity of hydrolyzing enzymes caused by endogenous auxin, resulting in mobilization of reserved food materials necessary for the initiation and development of roots. The low rooting in April and May is ascribed to the fact that bulk of the mobilized food was used up in the growth of sprouted branches leaving very little for rooting when these cuttings were planted. — The seasonal changes in the effectiveness of exogenously applied auxins also appear to be related with the level of endogenous auxin. In June endogenous auxin was high due to high meristematic activity, the exogenously applied auxins raising it to supra‐optimal levels that were inhibitory. On the other hand, in October exogenously applied auxins enhanced rooting by raising it to an optimal level as the production of endogenous auxin had been decreasing gradually due to lowering temperatures. — The results demonstrate that auxin effect on differential rooting with season in this plant is determined by the physio‐morphological status of the branches that govern the production of endogenous auxin and is mediated primarily through its effect on mobilization of reserve food materials caused by enhanced activity of hydrolytic enzymes.
The Mechanism of Boron Immobility in Plants
Authors: Oertli J. J. , Richardson W. F.
Published: April 2006

A mechanism is postulated to explain the immobility of boron in plants, i.e., the absence of any significant retranslocation of this element from one leaf to another. It is shown that boron readily enters the bark and is translocated within the bark. Since it has also been shown that boron remains water‐soluble in plants, the immobility cannot be explained through a chemical fixation, lack of entry into phloem, or absence of phloem transport. Rather, boron enters the phloem in leaf margins where concentrations are high, is transported in these conduits, is lost therefrom where the xylem concentration is low, i.e. in basal areas of the leaf and in petiole, is transported back in the xylem and accumulates in terminal place of the transpiration stream. A high local mobility of boron, together with the essentially unidirectional flow of the transpiration stream, thus cause a cyclic movement of B and prevent the efflux of this nutrient; this explains the immobility over long distances.
Effect of 2,4‐D on Cell Wall Metabolism of Peroxyacetyl Nitrate Pretreated Avena Coleoptile Sections
Authors: Ordin Lawrence , Garber Morris J. , Kindinger Juanita I.
Published: April 2006

Avena coleoptile sections were exposed to nonlethal concentrations of peroxyacetyl nitrate (PAN). The sections were then incubated in solutions of 50 mM glucose plus 2.5 mM poassium phosphate with various concentrations of 2,4‐dichlorophenoxycetic acid (2,4‐D). Growth after 4 hours was measured. A corresponding series of experiments was carried out with glucose‐14C (U) in the subsequent incubation medium and the effect of the 2,4‐D treatments on 14C incorporation into various cell wall components was determined. Growth in the PAN‐treated sections, although still partially inhibited, was greater at auxin levels normally superoptimal for growth than at the former optimum. Incorporation into all cell wall fractions was similar to growth in the case of control treated tissue. Most of the cell wall constituents, but particularly cellulose and less soluble noncellulosic polysaccharides, tended to show higher incorporation at the levels where PAN‐treated growth was also higher. It was concluded that effects by PAN on cell wall metabolism in growing tissue are similar to the effects on growth and that the mechanism of alleviation of growth inhibition is probably through decreased inhibition of wall metabolism.
Differentiation ex ovulo of Embryos and Plantlets in Stem Tissue Cultures of Tylophora indica
Authors: Rao P. S. , Narayanaswamy S. , Benjamin Bathsion D.
Published: April 2006

Tylophora indica callus tissue repeatedly subcultured every month on a series of different nutrient media in sequence regenerated roots, shoots and typical, bipolar embryos in vitro from unorganized callus parenchyma. The embryo‐like structures developed from somatic cells grew into normal plantlets when isolated and cultured on appropriate milieu of nutrients and hormones bypassing the normal sexual method of reproduction. Likewise, free cells in suspension also passed through embryonic stages reminiscent of development from fertilized egg.
Root‐promoting Substances in Salix alba
Authors: Kawase Makoto
Published: April 2006

Root‐promoting substances were extracted from softwood cuttings of Salix alba L. by centrifuging them with water or by shaking the ground freeze‐dried stems with water. Rooting substances were partitioned by paper chromatography or chemical fractionation and their rooting activity was tested by mung bean cuttings. Both extracts indicated three major root ‐promoting fractions at Rf 0‐0.1, 0.7‐0.8, and 0.3‐0.4 in a decreasing order of their activities when paper chromatographed with isopropanol:ammonia:water 8:1:1 v/v. The strongest one indicated an apparent synergistic rooting effect with indol‐3yl‐acetic acid (IAA) regardless of the extraction method. These results indicate that water can extract from freeze ‐dried sample the similar rooting substances found in the centrifugal diffusates. The Rf 0–0.1 fraction consisted of at least four fractions and the strongest one did not move from the starting line on the chromatogram when isopropanol:ammonia:water 8:1:1 was used. This starting line fraction was extremely strong in rooting activity and its highest concentration resulted in 8.7 times as many roots as controls. More thain additive rooting effect between IAA and the fraction was found only at the highest concentration. The fraction was very soluble in water but insoluble in chloroform or ethyl ether and only stimulated rooting of mung bean cuttings when it was applied within 3 days after cuttings were made. It had no effect in lengthening roots. The starting line fraction was further found to have four root‐promoting subfractions at Rf 0.05, 0.35, 0.65, and 0.85 when it was chromatographed in 60 % isopropanol. Among these four, the subfractions at Rf 0.65 and 0.35 were strongly root promotive and displayed more than additive root promotion with IAA at the highest concentrations studied.
La biosynthèse de l'acide indolyl‐3‐acétique en liaison avec le métabolisme du tryptophol et de l'indolyl‐3‐acétaldéhyde chez Rhizobium
Authors: Rigaud Par Jean
Published: April 2006

Several indolic compounds are formed when tryptophan or tryptamine is metabolized by Rhizobium. Among these are indole‐3‐acetaldehyde (IAAld), tryptophol (Tr‐ol), and indole‐3‐acetic acid (IAA). The metabolic relationship among the three compounds was investigated. The experiments were carried out either in the culture medium of growing Rhizobium cultures or in suspensions of washed bacterial cells. In neither case Tr‐ol would function as a precursor of IAA, but tryptophan‐2‐14G gave rise to the formation of both IAA and Tr‐ol. The ratio of IAA to Tr‐ol depended on the experimental conditions, shaking favoring the formation of IAA. Also IAAld gave rise to the formation of IAA and Tr‐ol when incubated with suspensions of washed cells. The ratio of the two compounds depended on experimental conditions such as pH value and shaking, the latter reducing the formation of Tr‐ol. These results cannot be explained by the assumption of a dismutation mechanism catalyzed by a single enzymatic unit. The operation of two enzyme systems, responsible for the reduction and the oxidation, respectively, of IAAld is suggested and discussed.
The Effect of a Non‐ionic Detergent on Some Plant Cells
Authors: Haapala Eva
Published: April 2006

The effects of a non‐ionic detergent. Triton × 100, on protoplasmic streaming in some plant cells, on plasmolysis, and on leakage of solutes from beet cells were investigated. The results of the different tests showed some features in common: (1) There is a critical range between 0.007 and 0.01 % v/v. (2) Above this concentration of the surfactant, that is at a concentration close to 0.01 %, the effect is manifested in the following ways. Plasmolysis with sucrose is anomalous or impossible. Protoplasmic streaming ceases within a short time. Definite leakage of ions and sugars starts from beet tissues. (3) At concentrations lower than 0.01 to 0.007 % there is enhanced retention of solutes in beet disks. — It is thought that the critical micelle concentration is of paramount importance. The micelle effect may consist in solubilizing or in forming mixed micelles or a complex with the globular lipoprotein units of the outermost plasma layer, the plasmalemma. The effect of the lower Triton concentrations is discussed.
Interaction of Epiphytic Bacteria and Activated Carbon on Root Growth
Authors: Burström H. G. , Persson P. I. , Stjernquist Ingrid
Published: April 2006

The influence of activated carbon and aseptic conditions has been studied on the growth of the primary root of wheat seedlings in order to ascertain whether or not the growth effect of activated carbon is connected with the occurrence of epiphytic bacteria. Growth was measured as mitotic activity, rate of cell elongation and duration of cell elongation. The surface infection of the septic roots probably consisted of common airborn and waterborn bacteria. Aseptic conditions increased the rate of cell elongation by ca 70 % but had no effect on the meristem activity. Activated carbon increased mitoses in the meristem and slightly augmented the duration of cell elongation but had no effect on the rate of elongation. The effects of sepsis and carbon were independent and appeared additative. Activated carbon removed inhibitors produced by the root tip itself but not those formed by the bacteria. In these experiments neither group of inhibitors seemed to contain IAA‐like substances.
Kinetics of Nicotinamide Adenine Dinucleotides during Dark‐Light Transients in Chlorella
Authors: Green W. G. E. , Israelstam G. F.
Published: April 2006

Nicotinamide adenine dinucleotides were extracted and assayed at frequent intervals for 30 seconds prior to and 60 seconds immediately following illumination of Chlorella cells. For these experiments a special illumination vessel was designed which dispensed 1 ml aliquots of algae with no dead volume. —White incandescent illumination of aerated Chlorella caused an immediate oxidation of its pyridine nucleotides. Under similar conditions blue light caused an initial reduction of these coenzymes. — White illumination of the alga perfused with CO2‐free air caused a transitory reduction of the pyridine nucleotide followed by an oxidation and a second reduction, Blue light, under similar conditions caused an immediate reduction but no oxidation as seen with white light. — When suspensions were perfused with N2, illumination produced a prompt and rapid oxidation of NADH. The extent of this oxidation was greater in white than in blue light. Under these conditions NADP+ was initially reduced and subsequently, temporarily oxidised. — The evidence offers some support for Lundegårdh's theory that blue light is more effective than red light in the photo‐reduction of NADP+. The results are discussed with referemce to the demonstrated in vitro reduction of nicotinamide adenine dinucleotides by chloroplasts and the conflicting reports from in vivo kinetic studies of living photosynthetic organisms. A scheme is proposed to explain the nicotinamide adenine dinucleotide kinetics as observed in these experiments.
Ribonuclease Activity and Auxin Effects in the Lens Root
Authors: Pilet P. E. , Braun R.
Published: April 2006

In Lens root tips, a direct proportionality between RNA and auxin levels and inverse proportionality between RNA content and RNase activity were found. IAA treatment of the Lens seedlings causes, in the root, both an increase of RNA and auxin content and a decrease of RNase activity. Addition of IAA to the excised roots produces an inhibition of both the decrease of the RNA levels and an inhibition of the increase of the RNase activity. The action of IAA on growth, related to the control of the RNA metabolism is discussed.
The Effect of Age and Chilling Temperature on the Concentration of Scopolin and Caffeoylquinic Acids in Tobacco
Authors: Koeppe D. E. , Rohrbaugh L. M. , Rice E. L. , Wender S. H.
Published: April 2006

Through the use of paper chromatographic separation, and fluorometric and spectrophotometric analysis, three caffeoylquinic acid isomers and scopolin have been quantilaed in tobacco as a function of age and chilling temperature. Coldchilled plants exhibited nitrate deficiency symptoms and 4‐5 fold increases over control plants in chlorogenic acid (CGA) concentration in all plant sections except the roots. Varying lesser increases in neochlorogenic acid, “Band 510”, and scopolin concentration were also observed in the above ground sections of chilled plants. Roots of cold‐chilled plants contained lesser concentrations of CGA and scopolin than control plants after 15 days of treatment. Leaves from the same control plant were found to decrease in CGA, Band 510 and scopolin concentration with age, while neochlorogenic acid concentrations changed little. In stem sections CGA concentration also decreased basipetally while the concentrations of scopolin increased. Similar leaf age studies done with cold‐chilled plants revealed phenolic concentration changes comparable to those of control plants, even though their concentrations were appreciably higher.
A Cellulase in Hevea Latex
Authors: Sheldrake A. R. , Moir G. F. J.
Published: April 2006

Using a viscometric method the latex of Hevea brasiliensis was found to contain a highly active cellulase capable of hydrolysing carboxymethyl cellulose. The enzyme has a pH optimum of around 6.3. It is present in the serum of the latex and is not membrane‐bound to any significant extent. Similar cellulase activities were detected in latex from old and new latex vessel rings and also in latex from regularly tapped vessels and newly tapped vessels. The possible role of the enzyme in the removal of cell wall material during the differentiation of latex vessels is discussed.
Pathways of IAA Production from Tryptophan by Plants and by Their Epiphytic Bacteria: A Comparison
Authors: Libbert Eike , Schröuder Roswitha , Drawert Anneliese , Fischer Elfriede
Published: April 2006

Metabolites of indoleacetaldehyde (IAAld), indoleethnol (tryptophol, IAAoI), tryptamine (TNH2) and indoleacetamide (IAAm) were investigated using 2 systems; a baeterial (Pea stem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). In both systems, indoleacetic acid (IAA), IAAol and indolecarboxylic acid (ICA) are produced from IAAld, and IAA and ICA are produced from IAAol (production of IAAld and ICAld not investigated). In the plant system TNH2 is converted to IAAld,IAA, IAAol and little ICA and ICAld. In the bacterial system TNH2 is converted to IAA, IAAol, the unknown substance Xb, and many ICA and ICAld. Xb is produced from IAAm, too. A nonacidie inhibitor extract from pea stems reduces the IAA gain from IAAld, IAAol and TNH2, and the IAAol and IAAld gain from TNH2; in the bacterial system it increases the IAAol gain from IAAld and the Xb gain from TNH2 and IAAm. Metabolic routes connecting Try, TNH2 and IAA are constructed for the plant tissue and for the epiphytic bacteria, respectively, including 4 sites of inhibitor action.
Studies on Protein Synthesis by Senescing and Kinetin‐treated Barley Leaves
Authors: Atkin R. K. , Sahai Srivastava B. I.
Published: April 2006

Using sterile conditions, changes in total protein synthesis were followed. over an 8 day incubation period, in detached first seedling leaves of barley from 8 day old plants during senescence and after kinetin treatment. In senescing leaves, total 14C‐alanine incorporation was enhanced by nearly 20% within 6 h of leaf detachment and by about 30 % after 24 h. Kinetin treatment stimulated protein synthesis even more, for total incorporation was promoted ca. 50 % after 6 h and by ca. 60 % after 24 h incubation. The leaf supernatant (30,000 ×g for 30 min) proteins were separated on DEAE‐Sephadex (A‐50) columns into approximately 14 fractions and changes in 14C labelling of these fractions were studied following leaf detachment and on incubation on water or kinetin for 6 days. In senescing leaves, 14C‐incorporation into supernatant proteins was sustained, even as protein levels declined rapidly The varied stabilities of the different leaf proteins was suggested by the characteristically changing specific activities of the different protein fractions. Although kinetin greatly promoted incorporation into all protein fractions, no evidence was surmised of specific effects on individual leaf proteins.

Studies of changes in total protein synthesis in attached senescing first seedling leaves taken from plants aged 7 to 27 days revealed a relatively small increase in 14C‐incorporation. However, incorporation could be greatly increased in leaves up to 15 days old by detaching and preincubating such leaves for up to 2 days on water, prior to measurement. The promotion of 14C‐incorporation into protcins follwing leaf excision could result from early changes in permeability and precursor pool size.
Fixation of CO2 and Export of Photosynthate by the Carpel in Pisum sativum
Authors: Lovell Peter H. , Lovell Patricia J.
Published: April 2006

Pods of Pisum sativum cv. Meteor were supplied with 14CO2 and the fixation and distribution of the radiocarbon studied. A high fixation rate was found in all of the treated pods. In intact control plants about 60 per cent of the total radiocarbon fixed was exported from the carpet into the seeds of the treated pod in the 24 hour period following fixation. Almost all of the remainder was relained in the carpel itself. It was found that the seeds in the treated pod were the major sink for these fixation products and that the weight of the seed determined the level of import of radiocarbon from the carpel in both attached and detached pods. Removal of the seeds from the treated pod prior to 14CO2 treatment reduced export from the fed carpel from 60 to 15 per cent, this being distributed mainly in the other pods and stem fractions. It appears that carpet photosynthate is likely to be of great importance in the growth and development of seeds enclosed by the carpel. control of fixation and export of radiocarbon seemed to be a function of the carpel and the seeds enclosed by the carpel and to be relatively independent of the rest of the plant. This could explain the absence of effect of GA on these processes.
Synthèse des RNA au cours de la germination du radis
Authors: Julien R. , Grellet F. , Guitton Y.
Published: April 2006

RNA synthesis in radish is studied during the first stages of germination. The radish seeds allowed to germinate in the dark, on distilled water, synthesize ribosomal RNA and accumulate a particular RNA, not incorporated in ribosomes. The results of 32P incorporation in RNA of radish seedlings indicate a progressive formation of ribosomal RNA. Two species of rapidly labelled RNA are synthesized. With labelling time, their chromatographic behaviour on MAK columus evolves, while their electrophoretic characteristics remain stable. It is assumed that these two species are involved in ribosome formation. In vivo experiments with chloramphenicol support this conclusion. RNA which accumulates during germination, could be a particular type of ribosomal RNA which could be enable, under the definite culture conditions, to enter into ribosomal structures.
Interaction entre Basidiomycètes mycorrhizateurs et racines de pin en presence d'acide indol‐3yl‐acetique
Authors: André Fortin J.
Published: April 2006

Interaction between mycorrhizal Basidiomycetes and pine roots in presence of indol‐3yl‐acetic acid. — La croissance de deux Basidomycètes mycorrhizateurs, Suillus variegatus (Sw. ex Fr.) et S. granulatus (L. ex Fr.) O. Kuntze a été rendue possible dans un milieu contenant au départ des quantités d'acide indol‐3yl‐acétique (AIA) inhibitrices pour ces champignons. Pour obtenir ce résultat, il a suffi d'ajouter au miliceu, des racines isolées et vivantes de pin (Pinus sylvestris L. et P. resinosa Ait.).

Plus la quantité d'AIA ajoutée au départ était grande, plus il fallait de racines pour renverser l'inhibition. L'exsudat des racines n'a produit aucun effet comparable.

Des mesures effectuées sur une solution d'IAI ont montré que les racines isolées de pin peuvent accumuler rapidement cette substance. Le taux d'accumulation est maximum aux valeurs de pH inférieures à 4.0 et devient très faible au voisinage de la neutralité.

L'auteur formule l'hypothèse qu'au cours de la formation des mycorrhizes ectotrophes chez le pin, la racine en accumulant l'AIA favorise la croissance du champignon en prévenant l'auto‐inhibition de son mycélium par l'AIA qu'il produit.
Effects of 6N‐Benzyladenine on Primary Leaves of Intact Bean Plants and on their Sodium Absorption Capacity
Authors: Jacoby B. , Dagan J.
Published: April 2006

The application of 6N‐benzyladenine (BA) to primary bean‐leaves attached to the intact plant resulted in increased leaf area. This was due to an extension of the duration of the period of leaf expansion.

The dry‐weight percentage of untreated leaves decreased continuously from emergence to abscission. In BA treated leaves this decrease stopped with the cessation of leaf expansion. Net chlorophyll synthesis occurs in untreated leaves as long as they continue to expand, shortly afterwards net chlorophyll decomposition starts. Benzyladenine treatments diminished the rate of chlorophyll synthesis immediately after its first application, but prevented the loss of chlorophyll afterwards. The abscission of primary leaves was also delayed by BA.

During the period of rapid leaf expansion in slices cut from BA treated leaves, sodium absorption rates were lower than in those from untreated leaves. From the age of 14 days after sowing, till abscission time of untreated primary leaves, the BA treatment did not significantly affect sodium absorption rates by leaf slices.
Regulation of Synthesis of Chlorophyll, Carotene, Ribulosel,5‐diP Carboxylase and Phosphoribulokinase in a Temperature‐sensitive Chlorophyll Mutant of Medicago sativa
Authors: Huffaker R. C. , Cox E. L. , Kleinkopf G. E. , Stanford E. H.
Published: April 2006

The activities of several enzymes were studied in a temperature‐sensitive chlorophyll mutant of alfalfa (Medicago saliva). In leaves grown at 10°C photosynthetic capacity was essentially nil with ribulose‐1,5‐diP carboxylase, chlorophyll, and carolene present in greatly limiting concentrations. The activity of phosphoribulokinase was 3.5 times lower at 10°C than at 27°C, but was still sufficiently high at 10°C to not limit the rate of CO2 fixation. Activities of phosphoriboisomerase, phosphoenolpyruvate carboxylase, glucose‐6‐P dehydrogenase and malate dehydrogenase were not different at 10°C and 27°C. The low fraction I protein content (which also accounts for the ribulose‐1,5‐dip carboxylase activity in alfalfa) indicated that synthesis of the carboxylase was effectively blocked at 10°C. A large, comparable increase in carboxylase activity and in concentration of fraction I protein in alfalfa leaves grown at 27°C indicated that the carboxylase was synthesized de novo.

The initial induction of the carboxylase, chlorophyll, and carotene may be related, but after induction the carboxylase was not linearly correlated with the other two and had a different temperature optima. Nevertheless, the synthesis of each appeared to be regulated by the temperature‐sensitive gene of this mutant.
The Conversion of Protochlorophyllide636 to Protochlorophyllide630 in Leaves Treated with δ‐Aminolevulinic Acid
Authors: Sundqvist Christer
Published: April 2006

Absorbancy changes in dark‐grown, excised wheal leaves fed with δ‐aminolevulinic acid are measured in vivo. The treatment with σ‐aminolevulinic acid caused accumulation of protochlorophyllide, absorbing at 636 nm. After flashlight this form is found to convert in darkness to protochlorophyllide, absorbing at 650 nm. The conversion starts instantly after the leaves have been exposed to the flashlight, and the pre‐existent pool of protocholorophyllidc absorbing at 650 nm will become emptied. The conversion is completed after 15–20 minutes, when a new pool of protochlorophyllide has been filled up. This new pool is transformed to chlorophyllide by a second flash and the sequence is repeated. The conversion may be composed of two reactions, a conclusion which can be drawn from the behaviour at different temperatures. One of these reactions is fairly temperature independent while the other is temperature dependent. The action of the protochlorophyllide holochrome is discussed.
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism
Authors: Libbert Eike , Silhengst Peter
Published: April 2006

Epiphytic, IAA‐producing bacteria strains were fed with 14C‐tryptophan (Try). 14C‐Try absorption and, after transfer to a Try‐free medium, 14C‐IAA output were stated. Using 4 different methods, the 14C‐Try containing bacteria were applied to the tips of sterile corn coleoptiles and the ‘diffusible’ auxin collected at the coleoptile bases by means of agar blocks.

14C‐IAA was detected in the agar blocks. Sterile coleoptiles the tips of which were wupplied with 14C‐Try also deliver some 14C‐IAA at their bases, but much less than both sterile coleoptiles supplied with 14C‐Try‐containing bacteria and nonsterile supplied with 14C‐Try.
Seasonal Characteristics of the Daily Fluctuation in Nitrate Reductase Activity
Authors: Roth‐Bejerano Nurit , Herman Lips S.
Published: April 2006

The daily fluctuation of nitrate reductase activity in leaves of tobacco may be controlled by the relative amounts of endogenous cytokinin and gibberellin. While plants growing during the summer exhibit maximum nitrate reductase activity at midday, winter‐grown plants show minimum activity at that time. One reason for this phenomenon seems to be a relatively higher level of endogenous kinin in winter‐grown plants. Salt‐stress treatment of these plants changes the fluctuation pattern of nitrate reductase activity from a winter to a summer type. Kinetin addition to summer‐grown plants changes their fluctuation pattern from a summer to a winter type.
The Effect of Histones and Other Basic Macromolecules on Cell Permeability and Elongation of Barley Roots
Authors: Drew M. C. , McLaren A. D.
Published: April 2006

Low exogenous concentrations of calf‐thymus histone, poly‐l‐lysine and lysozyme inhibit root elongation. These basic macromolecules (polycations) also affect cell permeability resulting in a leakage of ultraviolet light (UV)‐absorbing materials and chloride ion from cells. Adenosine 5′‐monophosphate was identified as one of the UV‐absorbing compounds in the root exudate, by thin layer chromatography. These deleterious effects of polycations on root growth and permeability are reduced in the presence of calcium and other divalent cations. Calcium ion‐histone interaction appears to exhibit competitive kinetics and suggests that both calcium and histone compete for attachment to negative sites on cell membrances.
14C‐Studies on Apple Trees. V. Translocation of Labelled Compounds from Leaves to Fruit and their Conversion within the Fruit
Authors: Hansen Poul
Published: April 2006

Following application of 14CO2 to fruit spur leaves, the majority of the 14C absorbed is transfered to the fruit on the same spur, and the total content of 14C within the leaf‐fruit system as a whole remains virtually constant with time. The considerable reduction in activity in the leaves is accounted for mainly by a decrease in the amount of 14C‐sorbitol, although relatively speaking the decrease in 14C‐sucrose is also considerable. The major part of the activity of the sugar fraction in the conducting tissues between blade and fruit (petiol, spur) is found in sorbitol. Immediately following uptake of 14C yia the leaves a large part of the activity of the sugar fraction in the fruit is found in sorbitol; but this activity is rapidly reduced, accompanied by an increase in sucrose activity, and over longer periods of time increases in particular in glucose and fruclose activity, and in that of methanol insoluble compounds. The changes in activity distribution in the fruit vary with the variety of fruit and the dates within the growing season.

By injecting labelled sorbitol directly into the fruit sorbitol is converted into sucrose, glucose and fructose, while injection of labelled sucrose, glucose and fructose has yielded proof of interconversions between these compounds but no measurable amounts of surbitol. After application of 14CO2 directly to the outer skin of the fruit considerably less of the activity is found in sorbitol than is the case in leaves following exposure to 14CO2.

A minor, but significant, translocation of 14C away from the fruit was found to take place following the application of labelled 14C compounds to the fruit.

The smallness of the respiratory loss of 14C in the leaf‐fruit system is discussed. It is concluded that in apple trees considerable translocation occurs in the form of sorbitol which in the fruits rapidly converted into other compounds.
Essai de localisation histochimique du zinc chez Hordeum gr. vulgare et toxicité
Authors: Gerebtzoff A. , Ramaut J. L.
Published: April 2006

The authors mention the importance of zine in plants, both as a toxic element in high concentration and as an indispensable one to some stages of cellular metabolism.

They study the localization of this oligo‐element by means of histochemical methods in Hordeum vulgare.

Zinc is found in the cytoplasm of the meristematic cells of the roots, in the cells of liber and on the grids of liber itserf. In the chlorophyllian parenchym, zinc is localized as minute particles in the near vicinity of chloroplasts.

The authors suggest that zinc interferes with the growth of plants; it seems to be a co‐enzyme to carbo‐anhydrase and it modifies the physico‐chemical conditions of extractibility of chlorophyll.
Herbicidal Effects on Water Uptake of Seeds of Selected Weed Species
Authors: Biswas P. K. , Haynes R. L.
Published: April 2006

Seeds of yellow foxtail, johnsongrass, pigweed and quackgrass were investigated to determine the effects of certain herbicides on water uptake by these species. Seeds of johnsongrass showed slight increase in water uptake over the 20‐h period when treated with 1, 5, 10, and 500 mg/1 of 2,4‐D. Tordon caused a most pronounced increase in water uptake at 0.1 and 1 mg/l as compared with the controls. Johnsongrass gave indications of either increases or decreases in water uptake when treated with herbicides during the 20‐h period, but showed no effects during the 10‐h period. Dormant seeds of yellow foxtail indicated an enhancement in water uptake at all 2,4‐D concentrations during the 20 h period. The effects which the different herbicides had upon the uptake of water in yellow foxtail seeds seemed to be directly proportional to increase in imbibition time. In all cases, more water was imbibed after 20 h over that observed at 10 h. During the 10‐h imbibition period, pigweed seeds treated with 2,4‐D was noted to have a slight stimulating effect on water uptake at all concentrations employed except 5 mg/l, which indicated a depressing effect. It was also observed that 2,4‐D caused a significant stimulating effect on water uptake of pigweed seeds over the 20‐h period as compared with the controls. A stimulation in the total quantity of water imbibed after 20 h was noted at dacthal concentrations below 100 mg/l whereas at the 500 mg/l, a slight depression in water imbibition was observed. At dalapon concentrations of 1 to 100 mg/l, a marked stimulation in total water imbibed by quackgrass seeds was shown during the 10‐h period.
Effect of Morphactin, Gibberellic Acid and Auxin and on Growth and Development of Bryophyllum tubiflorum
Authors: Nanda K. K. , Purohit A. N. , Kaura Neena
Published: April 2006

six month old LD‐ and SD‐ grown plants of Bryophyllum tubiflorum were treated with morphactin (n‐buty1‐9‐hydroxy‐fluorene‐(9)‐carboxylate), singly and in combination with GA3 and IAA.

Morphactin and IAA decreased stem elongation and number of leaves, the effect increasing with concentration concentation. Morphactin also caused lateral buds to develop into branches and the fusion of upper leaves to form structures of different shapes. GA3 enhanced stem elongation, increased leaf number and induced floral buds under SD conditions. It reversed the inhibitory effect of morphactin on stem elongation, leaf number and leaf fusion and also restored apical dominance when applied simultaneously with morphactin. The stimulaneous application of IAA also reversed the morphactin effects on leaf fusion and on apical dominance.

The results have been discussed in the light of literature available on the subject.
Rhizosphere Oxidation in Rice and other Species: A Mathematical Model Based on the Oxygen Flux Component
Authors: Armstrong W.
Published: April 2006

A mathematical model is presented from which one can predict the likely dimensions of oxidised rhizospheres due to oxygen diffusing from roots into anaerobic media such as wet soil. The analysis applies Fick's law of diffusion to the diffusion of oxygen from a cylindrical object (the root) into a sink (the soil) which is absorbing oxygen at a constant rate M. Solution of the final equation gives the dimensions of the oxygenated rhizosphere, i.e. the distance from the root at which the oxygen concentration becomes zero.

The results obtained supoprt the view that oxygen diffusing from roots will produce a rhizosphere ‘sheath’ charged with oxygen. Furthermore, some of the predicted limits for this oxygen sheath correspond with those of ferric iron sheaths around roots in waterlogged soils. Calculations also show that oxygenated rhizospheres around the roots of plants very tolerant of reducing conditions. e.g. Menyanthes trifoliata, Oryza sativa and Eriophorum angustifolium, should be from two to three times as broad as for Molinia coerulea which is a species intolerant of strong reducing conditions.

Consequently if oxidation reactions are not instantaneous but occur only gradually as quantities of reduced products enter the oxygenated zone, then the plants with the larger rhizospheres will be significantly better protected from absorbing large amounts of reduced products than will those plants with smaller oxygenated zones. This may in part explain the reason for intervarietal defferences in physiological disease resistance in rice.

Finally the observation is made that small lateral roots can be expected to oxygenate a zone nearly as large as, or probably larger, than the primary root from which they have arisen.
The Water Relations of Pinus sylvestris
Authors: Hellkvist Jerk
Published: April 2006

Comparative field studies of transpiration rate and drying‐transpiration in Scots pine were carried out in the autumns of 1964 and 1965 and in the early summer of 1966. The experimentl material was nineteen to twinty year old grafts, of the same clone but growing on different types of ground, or of different clones but growing in close proximity and under the same environmental conditions. Transpiration rates were measured on detached shoots. The results indicated that the type of ground did not very much modify the responses of the shoots to illumination‐darkness treatment.

Drying‐transpiration is here defined as the transpiration occurring when detached shoots are prevented from water uptake. Measurements were made of the rate of loss of weight and the amount of water given off from illuminated shoots. Defferences were found both in the rate of weight loss, and in the amount of water given off, between pine trees of the same clone but growing on different types of ground, and between pine trees of different clones but growing on the same type of ground.
Further Evidence for the Relative Immobility of Water in Sieve Tubes of Willow
Authors: Peel A. J.
Published: April 2006

Gradients of tritiated water, 35S‐sulphate and 32P‐phosphate, were established in isolated segments of willow stems. Sieve tube exudate was collected as honeydew from the high activity end of the segment. After girdling the stem a few centimetres from the site of sieve tube puncture, the specific activity of 35S and 32P in the honeydew rose, whilst the specific activity of tritium remained constant.

These findings indicate that prior to girdling, unlabelled sulphates and phosphates were contributing to the honeydew, whilst there had been no detectable contribution by unlabelled water from the low activity end of the segment.

The data support the conclusions drawn from previous experiments by Peel et al. (1969), that water is relatively immobile in sieve tubes of willow when compared to solutes.
Light and Nitrate Requirements for Induction of Nitrate Reductase Activity in Hordeum vulgare
Authors: Travis R. L. , Jordan W. R. , Huffaker R. C.
Published: April 2006

The importance of light to the induction of nitrate reductase activity in barley (Hordeum vulgare L.) was studied. Activity in etiolated leaves in darkness stayed at a low endogenous level even while large amounts of nitrate were actively accumulated. Light was required for any increase in activity, though the requirement may be satisfied to a limited extent before nitrate is available. Nitrate reductase activity was induced in the dark in green leaves which had not previously had nitrate but were supplied nitrate at the beginning of the dark period. If the nitrate then made available was sufficient, nitrate reductase activity increased until the effect of the previous light treatment was exhausted. Activity then decreased even though nitrate uptake continued. Upon returning the leaves to light, enzymatic activity increased again, as expected.

Nitrate uptake was eliminated as an experimental variable by giving dark‐grown plants nitrate, then detaching the leaves for induction studies. Under these conditions light saturation occurred between 3600 and 7700 lux at exemplary periods of illumination. At intensities of 3600 lux and above, activity increased sharply after a 6‐hour lag period. As light intensity was decreased below 3600 lux the lag period became longer. Thus, when sufficient nitrate was available, the extent of induction of nitrate reductase activity was regulated by light.
Uptake, Distribution and Translocation of 32P Absorbed through Roots of Cotton Seedlings as Affected with CCC Treatment
Authors: El‐Fouly Mohamed M. , Ismail A. A. , Abdalla F. E.
Published: April 2006

The effects of CCC on the 32 P amounts absorbed by cotton seedlings were studied. CCC was applied to the seedlings either as spray or as addition to the nutrient solution in concentrations of 0, 25, 50, 100 and 200 mg/1. 32P was added to the medium as KH232P O4 in the concentration of 40 μCi/50 ml.

During the experimental period, no morphological changes were observed. The total 32P uptake was inhibited in CCC treated seedlings. The application of CCC, both as spray and as addition to the medium, led to an accumulation of 32P in stem, but to a decrease in root. The leaves showed different responses to different methods of application; spraying increased, while an addition of CCC to the medium decerases the 32P content in the leaves. It is concluded that CCC inhibits 32P uptake, whereas it ac accelerates the 32P translocation from root to the aerial parts.
Induction and Repression of β‐Galactosidase Synthesis by Verticillum albo‐atrum
Authors: Keen N. T. , Long Margaret , Malca Isaac
Published: April 2006

Verticillium albo‐atrum grew on lactose‐containing culture media only after a prolonged lag phase. The intracellular specific activity of β‐galactosidase [EC 3.2.1.23] increased 40–200 times during he lag phase. The β‐galactosidase was induced by lactose and to a lesser degree by galactose. The appearance of the enzyme in lactose cultures was decreased by cycloheximide. Glucose and other readily metabolized carbon sources were effective repressors of β‐galactosidase production. The production of β‐galactosidase therefore appeared under control by lactose induction and catabolite repression.
The Effect of Colored Light on Pigment Synthesis in Cultured Fern Leaf Primordia
Authors: Haight Thomas H. , Kuehnert Charles Carroll
Published: April 2006

The effect of white, blue, yellow, red and far‐red light on the quantitative synthesis of the primary and auxilliary photosynthetic pigments in cultured leaf primordia of Osmunda cinnamomea L. is reported. The P660 form of the now classical photoreceptor pigment system, phytochrome, has been demonstrated to be active in chlorophyll synthesis in cultured cinnamon fern leaf primordia as shown by red/far‐red reversibility of chlorophyll synthesis. Also, it is apparent from the data presented that a blue absorbing pigment (P420) is responsible for the extensive accumulation of chlorophylls and carotenoids in these cultured leaves.
Fatty Acid Induced Leaking of Organic Compounds from Boletus variegatus
Authors: Lode Aaslaug , Pedersen T. A.
Published: April 2006

Addition of octanoic acid (2· 10‐3M) to the suspending medium (final pH 4.85) of Boletus variegatus mycelium induced a marked leaking of UV absorbing substances from the cells. The material had an absorption maximum at 260 nm, a minimum at 240 nm, and the absorption ratios 250: 260 and 280:260 were 0.81 and 0.49.

The material released immediately after addition of the acid consisted mainly of low molecular weight substances. These substances, listed according to decreasing rates of leaking, were identified as pentoses, pentosephosphates, nucleosides, and mono‐ and di‐nucleotides. Also, purine and pyrimidine bases were released at this early stage of treatment.

After 90 minutes' treatment, an outflux of oligoribonucleotides was observed. The oligoribonucleotides did not occur as single substances, but were forming complexes with peptides. Minor amounts of ribonucleic acid were also leaking out from the cells. Deoxyribose containing substances were never observed in the filtrates.

The compounds were subjected to enzymatic degradation after they had left the cells. This was shown by a marked increase with time of inorganic phosphorus, pentose/pentosephosphates, and nucleosides in the filtrate.

The leaking of low molecular weight substances immediately after acid addition is correlated to seriously reduced growth. However, the growth was wholly restored after a three days' lag period. On the other hand, when considerable amounts of oligoribonucleotide peptides had been released from the cells, growth could not be re‐established.
Changes in Germination Responses of Silene secundiflora in Relation to the Climate of its Habitat
Authors: Thompson P. A.
Published: April 2006

Silene secundiflora is a Mediterranean species restricted in range to the southern coasts of Spain and the Balearic Islands. Germination tests were made in incubators and on thermo‐gradient bars to evaluate changes in temperature‐responses at intervals after seed harvest. Results were compared to average temperatures occurring in the region and interpreted in relation to the climatic characteristics of the area.

Germination of freshly harvested seed was restricted to a narrow temperature band between ca. 7 and 16°C. After‐ripening during the first four months resulted in a progressive widening of the temperature band favouring germination, but this remained below average summer temperatures. Exposure of imbibed seed to high temperatures (31°C) reduced the subsequent temperature maximum for germination by about 4°C, but did not induce a fully effective secondary dormancy. The results appeared to be well correlated with a situation in which germination normally occurs in September at the start of the winter growing season.
Interactions between Peroxidases, Polyphenoloxidases and Auxin‐Oxidases
Authors: Pilet P. E. , Lavanchy P. , Sevhonkian S.
Published: April 2006

Root extracts, prepared from young Lens culinaris seedlings, are analysed after a gel chromatography on Sephadex G‐25 and G‐100.

IAA‐oxidase, peroxidase and polyphenoloxidase activities were found in the same fractions.
Penetration, Retention and Transport of Foliar Applied Single Salts of Na, K, Rb and Cs
Authors: Levi E.
Published: April 2006

The penetration, retention and transport of foliar applied chloride salts of Na‐22, K‐43, Rb‐86, and Cs‐134 were studied under controlled environmental conditions. Penetration although occurring at different rates was found to be non‐selective and appears to be a passive free diffusion process. Retention in the treated area is similar for Na, K and Rb and greater for Cs. Transport of these elements away from that area and in the plant was greatest and fastest for Na and Rb and slower for Cs and K. Distribution in the plants following leaf treatment was similar for K, Rb and Cs but no significant upward transport was noted for Na. Losses from roots were greatest for Na. No significant K could be detected in the culture medium 4 days after treatment of the leaves.