bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acide abscissique lié et dormance embryonnaire chez Pyrus malus
Authors: LE PAGE‐DEGIVRY M. Th. , BULARD C. 
Published: April 2006

Abstract Bound abscisic acid and embryo dormancy in Pyrus malus.The first part of this work was devoted to the study of the behaviour of Pyrus malus L. cv. Golden Delicious embryos cultivated in vitro. At the beginning of the experiment, either the root (RM) or the distal part of the cotyledons (CM) was immersed in the medium. For embryos directly isolated from the fruits at harvest time, as well as for embryos submitted to a 3‐month post‐maturation treatment at 4°C, the dormancy was deeper in CM cultures than in RM. The use of gibberellins (GA4 or GA7) emphasized these differences.The second part of this work was devoted to the study of free and bound forms of ABA (cis and trans isomers) in embryos isolated from the fruits at harvest time and cultivated by the RM or CM procedure during 3 weeks. The biochemical data obtained indicated in both cases the existence of the following three processes: (A) Mobilization of the bound ABA with the consequent release of free ABA; this was particularly important in CM. (B) Metabolism of free ABA: the isomerization into trans‐ABA only partly accounted for the decrease in the content of free ABA which was much greater in RM than in CM. (C) Transport of ABA towards the root, the result being an accumulation of free ABA in the root, much greater in CM than in RM; this would account for the deeper dormancy in CM than in RM.
Bromine, Bromophenols and Floridorubin in the Red Alga Lenormandia prolifera
Authors: PEDERSÉN MARIANNE , SAENGER PETER , ROWAN KINGSLEY S. , HOFSTEN ANGELICA V. 
Published: April 2006

AbstractThe pigment floridorunin was localized to the cuticle of the red alga Lenormandia prolifera (C. Ag.) J. Agardh by x‐ray micro‐analysis in Ihe transmission electron microscope and by its colour reactions in the light microscope. The pigment was set free from the cell wall by a pectinase. Bromine was also identified in the chloro‐plasts. the middle lamellae, the intercellulars and the pore plugs of the alga. The content of bromophenols in the alga increases with increasing age. The cell walls of old plants are stratified and their outer parts are apparently shed. The bromophenols could have a function as regulators of the epiphytes or the shedding of parts of the outer cell wall.
Distribution of Sodium and Chloride in Leaves of Suaeda monoica
Authors: ESHEL A. , WAISEL Y. 
Published: April 2006

AbstractA modified electron probe was used for the determination of the distribution of Na and Cl in cross sections of Suaeda monoica leaves. The results were corrected for differences in local mass values along the analysis line and expressed as percentage of the ions in the dried tissue. Sodium was found lo be selectively accumulated in the outer layer of chlorenchyma, whereas Cl was concentrated mostly in the cells of the inner chlorenchyma. Considerable pan of the osmotic potential of these cells is thus ascribed to the presence of those ions.
Comparison of Compartmental Analysis for Rb+ and Na+ in Low‐ and High‐Salt Barley Roots
Authors: BANGE G. 
Published: April 2006

AbstractThe size of the cytoplasmic pools of Rb+ and Na+ in roots of barley (Hordeum vulgare L.) was estimated by two independent methods:

. from the time curves of net Rb+ and Na+ uptake in low‐salt roots;
. from the kinetics of ion exchange in Rb+‐and Na+‐saturated roots.

The results indicate that in low‐salt roots there is a lag‐phase in vacuolar accumulation of Rb+ but probably not of Na+. At the same time part of the cytoplasmic Na+ pool seems to be excluded from rapid exchange. Both for Rb+ and Na+, flux reduction in saturated tissue appears to be more pronounced at the tonoplast than at the plasmalemma.
Abscisic Acid‐like Inhibitors and Cytokinins during After‐ripening of Dormant Peanut Seeds (Arachis hypogaea)
Authors: NARASIMHAREDDY S. B. , SWAMY P. M. 
Published: April 2006

AbstractChanges in abscisic acid‐like inhibitors and cytokinins were studied during dry storage after ripening of dormant peanut seeds. Decrease in ABA‐like inhibitors and increase in cytokinin levels was found as the seeds lose their dormancy. Dormancy of peanut seeds is associated with presence of a high level of ABA‐like inhibitors and a low level of cytokinins.
Efficiency of Root Respiration in Relation to Growth Rate, Morphology and Soil Composition
Authors: LAMBERS HANS 
Published: April 2006

AbstractRoot growth respiration and root maintenance respiration rate of the following species were determined: Hypochaeris radicata L. ssp. radicata L., H. radicata ssp. ericetorum Van Soest, Plantago lanceolata L., P. major L. ssp. major, P. major ssp. pleiosperma Pilgcr, P. maritime L., Senecio viscosus L., S. vulgaris L. and Urtica dioica L. A high root growth respiration (i.e. the amount of oxygen consumed for synthesis of a given weight of root material) implied a high maintenance respiration rate (i.e. the amount of oxygen consumed per unit of time and dry weight, but not connected with growth). High values of both components reflect a low efficiency of root respiratory processes.The efficiency of root respiration, as determined by the values for root growth respiration and root maintenance respiration rate could not be demonstrated to be of advantage in adaptation to soil conditions, as e.g. nitrogen content, moisture content and pH. It is concluded that (he degree of ‘wasteful utilization of sugars’ in roots, i.e. such consumption of sugars as cannot be related to structural growth, storage of carbohydrates or maintenance processes, depends on imbalance of transport of sugars from the shoot to the roots with utilization of sugars for synthesis of root material.The results are discussed in relation to Brouwer's explanation for the equilibrium between the growth of shoots and of roots. Root growth rate in the present species appears limited by a factor produced in the shoot under light conditions, and which factor is distinct from carbohydrates. The evidence presented shows that relatively inefficient root respiration does not imply a low growth rate. In regulation of plant growth the growth rate itself and also the shoot to‐root ratio may be more important than the regulation of the efficiency of energy metabolism.
Capacité caulogène de cellules de cal issues des couches cellulaires minces de type épidermique de ramifications florales de Nicotiana tabacum cv. Wise. 38 Par
Authors: HA NGOC K. A. , VAN TRAN THANH M. 
Published: April 2006

Abstract Bud formation capacity of callus formed from thin epidermal cell loyers excised from floral branches of Nicotiana tabacum cv. Wise. 38.Subepidermal cells of thin tissue pieces with a few cell layers were capable of forming eitber buds, roots, (lowers or non‐organ ogenetic callus. To determine wheiher this calltjs is able to dirferentiate into organs, we transferred it to media inducing eitber flowers, or buds, or roots. In this paper, we study ibe capacity of lbe callus to form buds. In 50% of the cases, the explants (being maintained for I day to 2 years in callus media) can still express the capacity to form buds. This percentage increased with increased agar concentration of the culture media. At the histological level, non‐organogenetic callus is characterized by the absence of tracheid differentiation, whereas in the organogenetic callus, iracheids were induced after their transfer into a ‘Bud medium’ and indicate an organogenetic differentiation pattern.
Effect of Auxin and Cytokinin on Newly Synthesized Proteins of Cultured Douglas Fir Cytoledons
Authors: HASEGAWA PAUL M. , YASUDA TAKESHI , CHENG TSAI‐YING 
Published: April 2006

AbstractNewly synthetized cyloplasmic proteins of Douglas fir cotyledon culture capable of initiating adventitious bud formation (bud culture) were compared with those of morphologically distinct types of cultures, bud‐callus culture (some adventitious buds with callus), and callus culture (no adventitious buds; only callus). SDS polyacrylamide gel electrophoretic profiles of double labeled (14C‐and 3H‐) proteins showed that a persistent increase of low molecular weight proteins (16,000 to 20,000 daltons) was associated with bud culture. Similar electrophoretic profiles of proteins extracted in the absence and in the presence of protease inhibitor (4‐mcthylbenzene sulfonyl fluoride) or phenolic compounds absorbents (Dowex I‐X8 and polyvinylpolypyrolidine) were obtained indicating that the detected low molecular weights of these proteins represented the real monomeric state of these molecules.
Alternating Perturbation Response of the Water Regulatory System in Arena Leaves
Authors: JOHNSSON A. , SKAAR H. 
Published: April 2006

AbstractThe transpiration response of excised primary Avena leaves was studied when pulse perturbations were given to the water regulatory system. Repeated light pulses given to the leaf caused regularly alternating transpiration responses, i.e. the magnitude alternated regularly between a high and a low value. This effect, denoted alternating pulse response, could be recorded under quite different light pulse conditions but was not found when the pulse interval was too long or too short (longer than about 60 min. shorter than about 15 min). Sodium chloride given to the transpiration stream induced and increased the effect. Alternating pulse response could also be recorded when mannitol pulses were given to the root system of intact plants.
Conditions for rooting of leafy cuttings of Alnus incana
Authors: HUSS‐DANELL KERSTIN , ELIASSON LENNART , ÖHBERG INGEGERD 
Published: April 2006

AbstractThe rooting of softwood cuttings of Alnus incana (L.) Moench in nutrient solution was studied under controlled conditions. Cuttings consisting of one internode with the leaf and axillary bud attached rooted easily and more rapidly than shoot tip cuttings. Light was necessary for rooting but good rooting was obtained in photon flux densities of both 40 and 190 μmol m‐2s‐1. Root number and root length was reduced when light reached the base of the cuttings. Treatment with indolebutyric acid (10‐6–10‐4M) increased the number of roots but 10‐4M delayed rooting and decreased the root length. Debudded internode cuttings rooted as well as intact cuttings, and detached leaves also contained sufficient substances for rooting.
Hardiness dependent accumulation of phospholipids in leaves of wheat cultivars
Authors: HORVÁTH I. , VIGH L. , BELEA A. , FARKAS T. 
Published: April 2006

AbstractPhospholipid content and composition in the leaves of thirteen cultivars of wheat differing in frost hardiness, were compared before and after hardening in order to see whether phospholipids play a role in surviving at low temperatures. The content of phospholipids in the leaves at the end of the hardening could be related to the aquired hardiness, and the relationship between the two phenomena could be described by the regression equation y = (0.174 ± 0.0016) x + 1311. Accumulation of phospholipids represents a hardiness dependent augmentation of membranes. Phosphatidylcholine appeared to be preferentially accumulated in hardy cultivars during the hardening process. As there are no significant differences in phospholipid fatty acid compositions investigated earlier, these results suggest the importance of the polar head group composition of membranes in avoiding frost injury.
Flower bud differentiation in Salix pentandra as affected by photoperiod, temperature and growth regulators
Authors: JUNTTILA OLAVI 
Published: April 2006

AbstractFlower bud initiation in seedlings and vegetatively propagated plants of Salix pentandra from different locations has been studied under controlled conditions. In mature plants flower bud formation was induced by 2‐chloroethyltrimethylammoniumchloride (CCC) and by short day treatment. The effect of CCC was antagonized by GA3. The critical photoperiod for flower bud formation was about 18 h for a southern clone (from 49°48'N), but cuttings of a northern ecotype (from 69°39'N) formed flower buds even at 24 h photoperiod. Generally, flower bud formation occurred simultaneously with apical growth cessation. However, apical growth cessation was not a prerequisite for floral initiation and flower buds were also found in elongating plants. Seedlings up to 60 days old did not form flower buds in growth chamber studies. The length of the juvenile phase has not been studied in detail, but cuttings taken from seedlings approximately 20 cm high and 60 days old were able to develop flower buds when treated with CCC. A gradual transition from the juvenile to the mature phase was obtained by repeated pruning of seedlings grown at 18°C and 24 h photoperiod.
Two temperature‐sensitive photosystem II mutants of pea
Authors: STUMMANN B. M. , VEIERSKOV B. , JACOBSEN S.‐E. , HENNINGSEN K. W. 
Published: April 2006

AbstractTwo nuclear gene mutants of pea, chlorotica‐887 and chlorina‐5756, are temperature‐sensitive in the development of photosystem II activity. Low temperature flourescence emission spectra of leaves show that the peak at 697 nm from the reaction center of photosystem II is present when the mutants have been grown at 18°C, but absent when they have been grown at 30°C. For leaves of chlorina‐5756 grown at 18°C the relative size of the peak at 697 nm is reduced compared to that of leaves of the wild type or chlorotica‐887 grown at this temperature. Flourescence induction curves of leaves from wild type plants and chlorotica‐887 grown at 18°C possess two steps, while those of leaves from chlorina‐5756 grown at 18°C or 30°C and chlorotica‐887 grown at 30°C show at fast rise to the maximal level of fluorescence. Measurements on chloroplasts isolated from the mutants indicated that the photosystem I activity per g leaf material is comparable for plants grown at 18°C and plants grown at 30°C. In contrast, no photosystem II activity was detected when the mutants had been grown at 30°C. It is suggested that these mutants are affected in a component required for the assembly of functional photosystem II complexes.
Photosynthate partitioning into leaf starch as affected by daily photosynthetic period duration in six species
Authors: CHATTERTON N. JERRY , SILVIUS JOHN E. 
Published: April 2006

AbstractStarch accumulation rates increased up to five‐fold in the leaves of five out of six species examined when plants were shifted from a long (12 or 14‐h) to a short (7‐h) photosynthetic period. The five species that responded were corn (Zea mays L.), pangola (Digitaria decumbens Stent.), soybean (Glycine max L.) Merr.), spinach (Spinacia oleracea L.), and sugarbeet (Beet vulgaris L.) However, the rate of starch accumulation in alfalfa (Medicago sativa L.) was unaltered following a shift from a long to a short photosynthetic period. We conclude that photosynthate partitioning into chloroplast starch, at least in a wide variety of species, is a programmable process that can be manipulated by altering the length of the daily photosynthetic period.
Metabolism of diclofop‐methyl (methyl‐2‐[4‐(2′,4′‐dichlorophenoxy)phenoxy] propanoate) in cell suspensions of diploid wheat (Triticum monococcum)
Authors: DUSKY J. A. , DAVIS D. G. , SHIMABUKURO R. H. 
Published: April 2006

AbstractThe metabolism of the herbicide, diclofop‐methyl (methyl‐2‐[4‐(2′,4′‐dichlorophenoxy)phenoxy]propanoate, in cell suspensions of resistant diploid wheat (Triticum monococcum L.) was determined 1, 8, and 24 h after treatment with 14C‐diclofop‐methyl. The 14C‐labeled products were identified by thin layer chromatographic comparisons to appropriate standards. Eight hours after treatment with 5 μM diclofop‐methyl in 0.8% acetone (neither of which were toxic to the cell suspensions) 87.2% (84.0% methanol soluble, 3.2% methanol insoluble) of the total 14C recovered (90.4%) was in the cells and 12.8% was in the medium. Major metabolites found in methanol extracts of the cells were diclofop (2‐[4‐(2′,4′‐dichlorophenoxy)phenoxylpropionic acid), diclofop hydroxylated at an undetermined position on the 2,4‐dichlorophenyl ring (ring‐OH diclofop), and conjugates of ring‐OH diclofop. Acid hydrolysis of the conjugated metabolite(s) yielded ring‐OH diclofop and diclofop. Twenty‐four hours after treatment 70–75% of the total 14C recovered was present as conjugated metabolites. With the exception of ring‐OH diclofop, all metabolites present in the cells were also recovered from the medium. A metabolite found in low concentrations in the medium that yielded diclofop upon hydrolysis was identified as an ester conjugate. Toxic concentrations of diclofop‐methyl (10 and 20μM) had no effect on the metabolism of the herbicide, although the rate of uptake was slower than for cells treated with 5 μM herbicide. The products of diclofop‐methyl metabolism in cell suspensions of T. monococcum were compared to previous data from T. aestivum intact plant metabolism of diclofop‐methyl.
The role of the leaves in the regulation of internode elongation in Phaseolus vulgaris
Authors: KIGEL JAIME 
Published: April 2006

AbstractTime‐course patterns of leaf and internode elongation were studied in bean plants. Each leaf started its main elongation period when the leaf below reached half of its final length. The onset of leaf unfolding was nearly synchronous with the initiation of the elongation of the subjacent internode. Excision of young leaves increased the rate of stem elongation as a result of an earlier unfolding of the next upper leaves and the concomitant advancement in the elongation of their subjacent internodes. IAA or NAA (1% in lanolin) suppressed the enhancement effects of leaf excision on leaf and internode elongation. The excision of a young leaf increased the final length of internodes located below it, and at the same time decreased the final length of the internodes located above the excised leaf. The reduction was greater the younger the internode. Differences in internode elongation after leaf excision were related to changes during internode ontogenesis in their relative response to the availability of assimilates on the one hand, and on the other hand to hormonal factors transported acropetally from the young leaves to the growing internodes.
The occurrence of free and bound cytokinins in clubroots and Plasmodiophora brassicae infected turnip tissue cultures
Authors: DEKHUIJZEN H. M. 
Published: April 2006

AbstractThis paper deals with the quantitative determination of free and bound cytokinins in clubroot tissue and in Plasmodiophora brassicae Woron, infected Brassica campestris L. callus tissue. The fractions were separated in a butanol soluble fraction containing the free cytokinins such as zeatin and zeatin riboside and a water soluble fraction containing the bound cytokinins.The butanol fraction was extensively purified and analysed by high pressure liquid chromatography (HPLC). The butanol fraction contained cytokinins which cochromatographed with zeatin and zeatin riboside and not with dihydrozeatin. Zeatin and zeatin riboside were quantitatively determined by HPLC. Recovery of the cytokinins varied between 30–50%. Clubs contained 50–160 ng zeatin and 210–300 ng zeatin riboside per g dry weight. Callus tissue contained 133 ng zeatin and 169 ng zeatin riboside per g dry weight.Clubs, callus as well as healthy tissue contain large amounts of bound cytokinins. Upon treatment of the water soluble fraction first with alkaline phosphatase and then with β‐glucosidase biologically active fractions were found which coeluted with zeatin and zeatin riboside on Sephadex LH20 in 20% ethanol. Evidence is presented for a novel cytokinin in the water soluble fraction which yields free zeatin and glucose‐6‐phosphate after treatment with β‐glucosidase.
Effect of some heterocyclic herbicides on CO2 assimilation by spinach chloroplasts
Authors: DÍAZ MARÍA A. , CHUECA ANA , GORGÉ JULIO L. 
Published: April 2006

AbstractWe have studied the inhibitory effect of heterocyclic herbicides simazine, paraquat, pyrazon and amitrole on photosynthetic CO2 fixation and on the level of intermediates of the CO2 assimilation cycle in isolated spinach (Spinacia oleracea) chloroplasts, as well as their in vitro activities on ribulose‐1,5‐bisphosphate carboxylase and fructose‐1,6‐bisphosphatase. The half inhibitory concentrations (I50) of CO2 assimilation were about 1 μM for simazine and paraquat, and 10 μM for pyrazon. Amitrole, with an I50 100 μM, gave only a weak inhibition. In the presence of simazine or pyrazon the triose‐phosphates/phosphoglycerate ratio diminished because of a decrease of the triose‐phosphates percentage from 47% to 19%, which means an inhibition of the phosphoglycerate reduction step by a low NADPH synthesis. However, there was not a parallel increase of phosphoglycerate, because of collateral pathways leading to phospho‐enolpyruvate, amino acids and other non‐identified compounds. Paraquat did not give such a decreased ratio, which could be explained as an inhibition of some step of the Calvin cycle later than triose‐phosphates by the H2O2 formed in a Mehler reaction. Amitrole did not show any effect on the pattern of intermediates. Simazine and pyrazon at 10 μM concentration promote a 20–30% activation of ribulose‐1,5‐bisphosphate carboxylase activity, whereas paraquat, pyrazon and simazine showed an I50 about 100 μM for the inhibition of the photosynthetic fructose‐1,6‐bisphosphatase.
Cytokinin production by Asparagus shoot apex cultured in vitro
Authors: KODA YASUNORI , OKAZAWA YOZO 
Published: April 2006

AbstractThe cytokinin producing capacity of asparagus (Asparagus officinalis L.) shoot apex was examined by means of shoot apex culture in vitro, where adventitious roots were never formed. The cultured shoot apices continued to diffuse a small but constant amount of cytokinin into the medium throughout five passages of subculture. The cytokinin content in the apices at the end of the subculture was not different from that at the beginning of the subculture. These results indicate a production of cytokinin by the apices.However, the finding is not in conflict with the hypothesis that the root tip is the major source of cytokinin supply, because the root tip of asparagus produced more cytokinin than the shoot apex and the decline of shoot growth observed during the subculture was partially restored by an application of zeatin into the medium.
The influence of water stress preconditioning on dark respiration
Authors: BROWN K. W. , THOMAS J. C. 
Published: April 2006

AbstractThe respiration rate of individual leaves of cotton (Gossypium hirsutum L. cv. Stoneville 213), beans (Phaseolus vulgaris L. cv. Bush Blue Lake), and sorghum (Sorghum vulgare Pers.) which had been fully expanded prior to a series of severe water stresses was compared with those of unstressed leaves of similar age. Measurements were made over a range of leaf temperatures. The respiration rate per unit area of the leaves of all rewatered plants were significantly lower than those of the plants which had not undergone water stress. During the stress periods, the leaves of all species suffered dry matter loss. The respiration rates per unit dry matter for cotton and beans were the same for the plants which had undergone stress as they were for the plants which had not undergone stress, thus for these two C3 plants the decrease in dark respiration due to water stress may be explained entirely by the loss of dry matter. Respiration rates of the water stressed sorghum leaves expressed on a per unit weight basis were significantly lower than those which had not undergone water stress preconditioning. The lower respiration rates of the stressed leaves when expressed on both a per unit area basis and a per unit weight basis for the C4 species indicate that water stress adaptation of C4 plants may include alterations in the respiratory mechanism or on the amount of residual respirable substrate. The light compensation points of all the species were not altered by the water stress preconditioning. This indicates that the mechanisms controlling the net photosynthetic exchange per unit leaf area underwent adaptations as a result of repeated water stress which decreased its efficiency.