Showing papers in "Plant Growth Regulation in 1985"
TL;DR: Although the sporadic identification of the conjugates formed between amines and cinnamic acids in various plants has been reported over many years, it is only recently that the widespread nature and potential significance of these amides has been recognised.
Abstract: In recent years polyamines have been shown to participate in various aspects of plant growth processes [1, 2, 4, 5, 14, 28, 67, 68, 69, 71]. In general, free putrescine, spermidine and spermine were the only amines measured, and only little attention has been given to bound or conjugated polyamines. Although the sporadic identification of the conjugates formed between amines and cinnamic acids in various plants has been reported over many years, it is only recently that the widespread nature and potential significance of these amides has been recognised.
211 citations
TL;DR: In addition to pea and oat, PYRR-DH was also detected in corn, barley, soybean and broadbean, and the enzyme was inhibited by the NAD analogs thionicotinamide and aminopyridine dinucleotide.
Abstract: Both mono- and dicotyledonous species catabolize putrescine to γ-aminobutyric acid (GABA), but by two different pathways. GABA is the major labeled product in pea shoots and oil leaves fed with a 2–4 h pulse of [l,4-14C]-putrescine (Put) or [1,4- tetramethylene-14C]-spermidine (Spd), respectively.In the presence of 1-10μM gabaculine, a specific inhibitor of GABA:pyruvate-transaminase, the label appearing in GABA increase 2 to 7-fold, which indicates that the transmination reaction is a major fate of GABA formed from Put or Spd In vivo. The conversions to GABA were demonstrated in vitro in coupled assays involving diamine oxidase from pea or polyamine oxidase from oat, and pyrroline dehydrogenase (PYRR-DH). The latter enzyme from either pea or oat is strictly NAD-dependent and is specific for pyrroline. The optimal temperature (40–45°C) and pH (7.5–8.0) are similar to those of bacterial PYRR-DH. In all cases the enzyme was inhibited by the NAD analogs thionicotinamide and aminopyridine dinucleotide (0.1—1.0 mM). In addition to pea and oat, PYRR-DH was also detected in corn, barley, soybean and broadbean Di-and polyamine oxidase are released by enzymes which degrade the cell wall, while PYRR-DH remains associated with the protoplast.
129 citations
TL;DR: The thigmomorphogenetic response in Bryonia dioica can be considered as a mechanism of resistance in order to withstand further environmental mechanical perturbation.
Abstract: Rubbing young internodes ofBryonia dioica results in a reduced elongation and an increased diameter of the internodes. In the present study activities of some enzymes involved in the lignification process and levels of lignification were compared in rubbed and non-rubbed internodes. Rubbing caused an increase in the activities of phenylalanine ammonia-lyase and soluble and ionically- and covalently-bound cell wall peroxidases. Sensitivity of the covalently-bound wall peroxidase assay was markedly increased if syringaldazine was used as a substrate. Mechanical perturbation induced an increase in lignin, lignin monomer (sinapylic, coniferylic and p-coumarylic alcohols) content and the number of lignifying vessels. Conversely, rubbing resulted in a decrease in cellulose content. The hypothetical interpretation of the thigmomorphogenetic response through cell wall lignification and hence rigidification is consistent with all the presented results. A comparison is possible between this accelerated lignification and induced lignification as a mechanism of disease resistance. the thigmomorphogenetic response inBryonia dioica can be considered as a mechanism of resistance in order to withstand further environmental mechanical perturbation.
91 citations
TL;DR: A block in the conversion of the diamine putrescine to the triamine spermidine may be an important step in the change from cell division to cell elongation in pea roots.
Abstract: The levels of putrescine, cadaverine, spermidine and spermine were determined in seedling roots of pea, tomato, millet and corn, as well as in corn coleoptiles and pea internodes. In all roots, putrescine content increased as elongation progressed, and the putrescine/spermine ratio closely paralleled the sigmoid growth curve up until the time of lateral root initiation. Spermidine and spermine were most abundant near the apices and declined progressively with increasing age of the cells. In the zone of differentiation of root hairs in pea roots, putrescine rose progressively with increasing age, while cadaverine declined. In both pea internodes and corn coleoptiles, the putrescine/spermidine ratio rises with increasing age and elongation. Thus, a block in the conversion of the diamine putrescine to the triamine spermidine may be an important step in the change from cell division to cell elongation.
52 citations
TL;DR: The spermidine synthesis inhibitors methylglyoxal bis-(guanylhydrazone) (MGBG) and dicyclohexylammonium sulfate (DCHA) were found to reduce growth and embryogenesis in wild carrot cultures, suggesting that the polyamines, especially sperMidine, play an important role in the growth and development of plants.
Abstract: The spermidine synthesis inhibitors methylglyoxal bis-(guanylhydrazone) (MGBG) and dicyclohexylammonium sulfate (DCHA) were found to reduce growth and embryogenesis in wild carrot cultures. Cellular polyamine levels were also affected by the inhibitors, with spermidine levels being especially reduced by DCHA. Similarly, MGBG reduced organogenetic development of shoots on excised aspen hypocotyls. These data suggest that the polyamines, especially spermidine, play an important role in the growth and development of plants.
51 citations
TL;DR: Polyamine titers were measured in aseptically cultured mesophyll protoplasts of Vigna and Avena to study possible correlations between polyamines and cellular behavior and the effects on internal polyamine titer, cell division activity and regenerative events.
Abstract: We have previously reported that aseptically cultured mesophyll protoplasts of Vigna divide rapidly and regenerate into complete plants, while mesophyll protoplasts of Avena divide only sporadically and senesce rapidly after isolation. We measured polyamine titers in such cultures of Vigna and Avena, to study possible correlations between polyamines and cellular behavior. We also deliberately altered polyamine titer by the use of selective inhibitors of polyamine biosynthesis, noting the effects on internal polyamine titer, cell division activity and regenerative events. In Vigna cultures, levels of free and bound putrescine and spermidine increased dramatically as cell division and differentiation progressed. The increase in bound polyamines was largest in embryoid-forming callus tissue while free polyamine titer was highest in root-forming callus. In Avena cultures, the levels of total polyamines decreased as the protoplast senesced. The presence of the inhibitors alpha-difluoromethyl-arginine (specific inhibitor of arginine decarboxylase), alpha-difluoromethylornithine (specific inhibitor of ornithine decarboxylase) and dicyclohexylamine (inhibitor of spermidine synthase) reduced cell division and organogenesis in Vigna cultures. Addition of low concentration of polyamines to such cultures containing inhibitors or removal of inhibitors from the culture medium restored the progress of growth and differentiation with concomitant increase in polyamine levels.
42 citations
TL;DR: Investigation into menadione sodium bisulphite's effect on auxin metabolism resulted in decreased activities of the enzymes involved in IAA oxidation in tomato plants, increasing the levels of IAA following application of MSB.
Abstract: Menadione sodium bisulphite (MSB) increased the growth of tomato plants and alfalfa callus and stimulated rooting of mungbean cuttings. Investigations into its effect on auxin metabolism resulted in decreased activities of the enzymes involved in IAA oxidation in tomato plants. The levels of IAA were increased by about 3 to 4 fold following application of MSB to tomato, cucumber, corn and capsicum plants.
30 citations
TL;DR: The early pioneering investigations of Smith and others on K+-deficient barley leaves set the stage for the elucidation of the general metabolic sequence involved in the biogenesis of these amines in plants and pinpointed the important roles PAs play in maintenance of intracellular pH and ionic balance.
Abstract: The polyamines (PAs), spermidine (SPD) and spermine (SPN) and their diamine precursor, putiescine (PUT) represent a set of evolutionarily highly conserved small molecular weight organic polycations which play vital roles as modulators of a plethora of biological processes from enzyme activation and maintenance of ionic balance, through regulation of growth and development, to mediation of hormone action and progress of cell division cycle. Because of this functional versatility, research on PAs represents one of the most vigorously pursued areas of modern biology. While most of the currently available information on these important classes of bioregulators is derived from microbial and animal systems, interest in their possible participation in various facets of plant biochemistry and physiology is of relatively recent origin. The early pioneering investigations of Smith and others [34, 48. 62, 54, 63] on K+-deficient barley leaves, set the stage for the elucidation of the general metabolic sequence involved in the biogenesis of these amines in plants and pinpointed the important roles PAs play in maintenance of intracellular pH and ionic balance. However, with the recognition that plant systems also offer tremendous potential for unravelling the riddles concerncd with the biological functions of PAs. new vistas have been opened in plant PA research.
28 citations
TL;DR: In tomato fruits grown in vitro, in which basic growth processes are inhibited, the activity of ODC and arginine decarboxylase (ADC) and the level of free polyamines were reduced and the free polyamine content was correlated with the DNA content, cell size, and fruit fresh weight.
Abstract: The apparent involvement of ornithine decarboxylase (ODC) and putrescine in the early stages of fruit growth in tomato (Lycopersicon esculentum Mill.) has been previously described. Further evidence presented here supports the direct involvement of ODC and putrescine in the cell division process in tomato fruits. In tomato fruits grown in vitro, in which basic growth processes are inhibited, the activity of ODC and arginine decarboxylase (ADC) and the level of free polyamines were reduced. While ODC and ADC activity was correlated with the period of cell division in the tomato fruit, the free polyamine content was correlated with the DNA content, cell size, and fruit fresh weight. The addition of exogenous putrescine, however, did not restore the basic growth processes in the fruits grown in vitro.
24 citations
TL;DR: Variations in polyamines, proteins and RNA during in vivo gametogenesis and in vitro androgenesis in Datura innoxia and in Nicotiana tabacum were studied and the role of polyamines in both species was discussed.
Abstract: Variation in polyamines, proteins and RNA during in vivo gametogenesis and in vitro androgenesis in Datura innoxia and in Nicotiana tabacum were studied. Spermidine was the major polyamine during gametogenies in both species. Marked differences in proteins, RNA and polyamines were evident during meiosis and at the first haploid mitosis. In Nicotiana an unknown amine (X60) appears at the beginning of the first haploid mitosis. At the same time a rapid increase in the concentrations of RNA and proteins is observed. In Datura, at the time of the first haploid mitosis there is large increase in amine and RNA levels followed by an arginine peak. During androgenesis, putrescine and spermidine were the major polyamines In both species. In Nicotiana during androgenesis an unknown amine (X81) was observed together with putrescine and spermidine. This unknown compound peaks during the developmental stages of embryogenesis. In Datura androgenic induction was marked by an arginine peak followed by an increase in the putrescine and spermidine levels associated with maximum RNA. These biochemical events arc tentatively correlated with structural changes during pollen development. The significance of these results is discussed in relation to the role of polyamines during gametogenesis and androgenesis.
20 citations
TL;DR: Examination of the distribution of hormones in the fruiting plant reveals that active growth meristems such as shoot tips and seeds contain high levels of auxins, cytokinins and gibberellins, their relative concentrations varying with different stages of development.
Abstract: Fruit development consists of several key physiological processes from fruit bud formation through flower development and evocation to pollination leading to fertilization of the ovule, seed development and fruit expansion and eventual maturity. Flowering, fruit set and retention, are markedly influenced both by environmental factors and internal relationships between the various organs of the tree. An improvement in the understanding of the mechanisms regulating these processes is central to achieving the objectives of increases in yield of fruit of good size and quality and of regularity of cropping. Of particular importance to achieving control of fruit set and retention is the requirement for knowledge of the underlying causes of embryo abortion and fruitlet abscission. The internal regulation of tree and fruit development may be considered in the simple sense of competition between meristems for available nutrient resources from both leaf and root sources. The differing demands for nutrients, or relative ‘sink-strength’, of the various organs has long been considered to be associated with the activity of plant hormones [24]. Examination of the distribution of hormones in the fruiting plant reveals that active growth meristems such as shoot tips and seeds contain high levels of auxins, cytokinins [ 181 and gibberellins [6] , their relative concentrations varying with different stages of development. Although it cannot automatically be assumed that active growth is a result of high hormone levels, since it is equally possible that they are produced, or accumulate, in tissues in consequence of growth, the profound effects of applied hormones suggest causal relationships with growth and development [24], Study of the mechanisms and mode of action of the various classes of plant hormone
TL;DR: The effects of benzoquinone, naphthaquinone and anthraquinone on the growth of tomato callus, whole plants of tomato and on rooting of mungbean cuttings were studied in this paper.
Abstract: The effects of benzoquinone, naphthaquinone and anthraquinone on the growth of tomato callus, whole plants of tomato and on rooting of mungbean cuttings were studied. Naphthaquinone effects on some oxidases and on the isozyme patterns of peroxidases in all the three systems were also observed. Quinones increased callus growth, the number of roots initiated in mungbean cuttings and the growth of tomato plants, significant increases being obtained with 10−5M naphthaquinone. Naththaquinone also decreased the activities of IAA oxidase, ascorbic acid oxidase and polyphenol oxidase, and led to the disappearance of one of the isozyme of peroxidase in all systems.
TL;DR: It is concluded that the involvement of gibberellin in celery seed dormancy is not dependent on endogenous ethylene and is directly or indirectly controlled through the action of other hormones on transmembrane ion fluxes.
Abstract: The temperature-dependent primary dormancy of cv Florida 683 celery seeds in darkness was broken by GA4/7 (2 × 10-4 M) alone but other growth regulators such as BA, ethephon or daminozide were necessary to break dormancy of cv Lathom Blanching seeds in the presence of GA4/7 at this concentration. Although AgNO3 partially inhibited both the ethephon- and BA- induced germination of cv Lathom Blanching seeds in the presence of GA4/7 in the dark it did not affect the promotive action of daminozide. Ethephon did not overcome the inhibitory action of high concentrations of AgNO3 in the light. The ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG) did not inhibit the germination of cv Lathom Blanching seeds induced by growth regulators in the dark or in the absence of growth regulators in the light. Fusicoccin (FC) did not break celery seed dormancy unless applied in the presence of GA4/7. Germination of cv Lathom Blanching celery seeds treated with GA4/7 at 16°C in the dark was inhibited by the K+ ionophore benzo-18-crown-C-6 (18-C-6) and in the presence of Ca2+ by the Ca2+ ionophore A23187; the 18-C-6 inhibition was reversed by BA. It is concluded that the involvement of gibberellin in celery seed dormancy is not dependent on endogenous ethylene and is directly or indirectly controlled through the action of other hormones on transmembrane ion fluxes.
TL;DR: Comparison of various inorganic salts at 1 M showed that polyamine oxidase activity was enhanced in the order RbCl >KCl>KBr>NH4Cl>NaNO3> LiCl>LiCl=NaCl> control (no salt) >CaCl2=MgCl2.
Abstract: In a homologous series of di-guanidines (NH2C(= NH)NH(CH2)xNHC(=KH) NH2,) where x = 2–12, greatest inhibition of polyamine oxidase was found with x = 8.The synthetic fungicide guazatine
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was particularly effective as an inhibitor of polyamine oxidase, with Ki of ca 10− 8 M. Inhibition due to the triamine derived from guazatine by hydrolysis was less effective by a factor of ca 200. Comparison of various inorganic salts at 1 M showed that polyamine oxidase activity was enhanced in the order RbCl > KCl > KBr > NH4Cl > NaNO3 > LiCl = NaCl > control (no salt) > CaCl2 = MgCl2. Activity in RbCl was about 4 to 5 times greater than in the salt-free control. Enzyme activity is rapidly lost during assay. This loss of activity could not be attributed to inhibition by aminopropylpyrroline effect on enzyme activity.
TL;DR: The effect of root pruning on the growth and transpiration of colt rootstocks was measured in this paper, which showed that root pruned colts increased stomatal resistance and reduced root, leaf and stem weight.
Abstract: The effect of (2RS, 3RS)-1-(4-Chlorophenyl)-4, 4-dimethyl-2-(1H-1,2,4 triazol-1-yl) pentan-3-ol (PP333) on the growth and transpiration of normal and root pruned colt rootstocks was measured. PP333 reduced plant height, stem diameter increment, leaf number, area and weight and stem weight. Root pruning reduced root, leaf and stem weight, and plant height in control plants. PP333 reduced both total water use and transpiration per unit leaf area and increased stomatal resistance. In control plants root pruning also reduced total water use and increased stomatal resistance. 15 days after the beginning of the experiment half the plants in all treatments were allowed to dry out. The effects of drought, i.e. reduced transpiration, growth and leaf water potentials, were smaller in PP333 treated than in control plants.
TL;DR: Fruits grownin vivo and in vitro were compared throughout their development according to various growth parameters: fresh and dry weight, cell number, cell diameter, and DNA and total protein content and indicate that the reduced fruit size in vitro is related to the reduction in both cell number and cell size.
Abstract: Tomato (Lycopersicon esculentum Mill.) fruits of the male sterile cultivar Pearson (MS35 BC4, 61) were transferred toin vitro culture during the cell division period. Fruits grownin vivo andin vitro were compared throughout their development according to various growth parameters: fresh and dry weight, cell number, cell diameter, and DNA and total protein content. In all cases, the values pertaining to fruits grownin vitro were significantly lower than theirin vivo counterparts. The final fresh weight of fruits transferred to culture 2, 5, or 10 days after pollination was only 0.7, 1.2, and 3.4%, respectively, of that of plant-grown fruits. The results indicate that the reduced fruit sizein vitro is related to the reduction in both cell number and cell size. It is interesting to note that the DNA content per cell increased 15-fold during the growth of the plant-grown fruits while this accumulation was only between 2-and 3-fold in all the cultured fruits. The time to first colour appearance of fruits cultured 2, 5, or 10 days after pollination was 196, 132 and 85%, respectively, of that of plant-grown fruits.
TL;DR: A mutant carrot callus line resistant to a high concentration (1 mM) of putrescine has been isolated and Ornithine-, arginine- and S-adenosylmethionine decarboxylase activities were similar in the resistant line and in the controls by the fifth subculture.
Abstract: A mutant carrot callus line resistant to a high concentration (1 mM) of putrescine has been isolated. A high level of endogenous putrescine, about 13-fold higher than in the controls grown in the absence of putrescine, characterized this resistant mutant. Ornithine-, arginine- and S-adenosylmethionine decarboxylase activities were similar in the resistant line and in the controls by the fifth subculture. The uptake of putrescine when supplied to the medium at high concentration (1 mM), was similar in both the putrescine-treated calli and in the untreated controls. At low concentrations (0.64 μM) however the putrescine absorbed by the resistant calli was less than that absorbed by the controls. Putrescine uptake took place almost always against a concentration gradient and might be due to an active mechanism.
TL;DR: Endogenous cytokinin activity was determined in the flowers of Cosmos sulphureus Cav.
Abstract: Endogenous cytokinin activity was determined in the flowers of Cosmos sulphureus Cav. from bud emergence to full bloom using the soybean callus bioassay. Cytokinin activity was low early in flower development but increased prior to full bloom. In Sephadex LH-20 column chromatography of flower extracts, the cytokinins present co-eluted with zeatin, zeatin riboside and glucoside cytokinin. While the former two predominated prior to full bloom, cytokinin glucoside activity appeared to be at a maximum at full bloom. The possible relevance of these findings is discussed in relation to flower development.
TL;DR: The inverse ratio between growth processes and changes in polyamine and proline level indicates that polyamines fulfil primarily a protective and osmorepulatory function in plant cells under NaCl sttess.
Abstract: The polyamine titers in three cell lines of Nicotiana sylvestris were compared: Type 1, rapidly adapting to NaCl: Type 2, constantly resistant to NaCl; Type 3, a salt-sensitive wild strain During short-term cultivation in MS medium in the presence of 170mM NaCl (1 passage, 14 d) the changes in polyamine titer in cell suspensions of type 1 (in a slightly adapted state) and non-adapted wild strain (type 3) showed a considerable increase in spermidine and spermine and a decrease in putrescine After prolonged adaptation to NaCl (20 passages) the putrescine content in the cells of type 1 and of type 2 was increased at the expense of the polyamines This suggests that the pattern of polyamine titer varies under short- and long-term adaptation to NaCl The inverse ratio between growth processes and changes in polyamine and proline level indicates that polyamines fulfil primarily a protective and osmorepulatory function in plant cells under NaCl sttess
TL;DR: The radiation (32P) induced dwarf mutant of spring barley, Hordeum vulgare L., Mut.
Abstract: The radiation (32P) induced dwarf mutant of spring barley,Hordeum vulgare L., Mut. Dornburg 576, was genetically studied by crosses with the mother variety and characterized by seedling assays and investigations on development and yield formation. In comparison to the normal mother variety (Hordeum vulgare L., cv. ‘Saale’) mutant plants exhibit drastically reduced culm length, intensive tillering, a prolonged life cycle and a smaller biomass and grain yield formation. These characters are controlled by one gene in a pleiotropic way. The mutant responds with normal growth and development to the application of gibberellins.
TL;DR: The results indicate that MGBG may inhibit not only the synthesis of Spd and Spm, but the catabolism of Put in the aleurone layer.
Abstract: Incorporation of L-[U-14C] aiginine or L-[U-14C] ornithine into putrescine (Put), spermidine (Spd) and spermine (Spm) in embryonectomized barley seeds(Hordeum vulgare L. cv. Himalaya) was studied following imbibition with methylglyoxal-bis (guanylhydrazone)(MGBG) and abscisic acid (ABA). Both radiolabeled amino acids were incorporated into the amines as a result of: active polyamine biosynthesis in the seed during imbibition. In the aleurone layer, the Spd and Spn existed mainly in the free form (acid soluble). However about 50% of Put was recovered in conjugated form (s) (acid insoluble). Imbibition with 5 and 10μM ABA for 3 days increased the accumulation of the tree form of 14C-Put. probably as a result of inhibition (70%) of 14C-Spd accumulation. The ABA treatment showed no significant effect on levels of the conjugated form of Put and Spd. Imbibition with millimolar concentrations of MGBG resulted in (i) abnormal accumulation of the free form of Put and incorporation of 14C-amino acids into the diamine, (ii) progressive inhibition of the accumulation of the free forms of 14C-Spd and Spm. and (iii) reduction of the 14C incorporation into the conjugated forms of Put and Spd. Uptake of 14C-amino acids was not affected by MGBG treatment. The results indicate that MGBG may inhibit not only the synthesis of Spd and Spm, but the catabolism (e.g. oxidation) of Put in the aleurone layer.
TL;DR: Soybean callus metabolised applied 6-furfurylamino (8-14C) purine very rapidly to polar compounds, some of which were retained on a Dowex 50 cation exchange resin, and were unaffected by alkaline phosphatase; while others were apparently phosphorylated and were detected in aqueous fraction.
Abstract: Soybean callus metabolised applied 6-furfurylamino (8-14C) purine very rapidly to polar compounds, some of which were retained on a Dowex 50 cation exchange resin, and were unaffected by alkaline phosphatase; while others were apparently phosphorylated and were detected in the aqueous fraction. Adenine was detected as an intermediate and it can be concluded that it was formed as a result of the rapid and efficient removal of the furfuryl side chain. The formed adenine was rapidly incorporated into the polar metabolites. Exactly how the presence of this cytokinin stimulates cell division is not apparent from the results.
TL;DR: Spermidine in the presence of ACC modulated the effect of ACC on the bud size while returning the internal polyamine content to control levels, and appeared to correlate with apical bud size and vigor but did not show any consistent relationship to apicals bud senescence.
Abstract: The effect of various treatments on the apical senescence and polyamine content of apical buds of G2 peas was analysed. Defruiting prevented senescence and increased bud size and polyamine content. Exogenous applications of GA20 enhanced bud size and spermidine concentration. Applied spermidine had a slight effect on spermidine level but did not delay senescence. ACC strongly induced adecrease in bud size and, at 10mM, apical senescence. This was accompanied by a steady decline in the level of all polyamines though their concentration remained constant until 10 mM ACC, where a drop was noted. Spermidine in the presence of ACC modulated the effect of ACC on the bud size white returning the internal polyamine content to control levels. AVG, an inhibitor of ACC synthesis produced pronounced increases in putrescine though no apparent effect on apical bud growth. Polyamine synthesis inhibitors were without effect on growth or internal polyamine content. The internal polyamine content appeared to correlate with apical bud size and vigor but did not show any consistent relationship to apical bud senescence.
TL;DR: An antizyme extracted from chromatin by 2 M NaCl and purified to homogeneity reacts with both cytosolic and chromatinbound ornithine decarboxylase from germinated barley seeds and E. coli, but it does not inhibit ornithines decar boxylase of Tetrahymena pyriformis or rat liver.
Abstract: The purification of a chromatin-bound antizyme to ornithine decarboxylase from germinated barley seeds is described. This antizyme was extracted from chromatin by 2M NaCl and purified to homogeneity. Its molecular weight was found to be 9000 with an isoelectric point of 4.1. It reacts with both cytosolic and chromatin- bound ornithine decarboxylase from generated barley seeds and E. coli but it does not inhibit ornithine decarboxylase of Tetrahymena pyriformis or rat liver.
TL;DR: Spermine in the chromatin preparation was almost fully solubilized by a DNase-treatment, but spermidine was less easily solubile, and most of the spermine associated with the chromation is chromatin-specific.
Abstract: Chromatin prepared from maize shoot tips using as extraction medium including quinacrine as an inhibitor of polyamine oxidase, contained 1.6 pmol spermidine μg DNA-1 and 14.8 pmol spermine μg DNA-1, respectively. This represented 0.1% spermidine and 3.7% spermine as compared with the content of those amines in the whole tissue. No putrescine was detectable in the chromatin preparation. When contamination of polyamines in the preparation was determined by the addition of labeled polyamines to the extraction medium, the ratio of the polyamines in the preparation to those in the extraction medium was 0.1% spermidine and 0.7% spermine, respectively. Spermine in the chromatin preparation was almost fully solubilized by a DNase-treatment, but spermidine was less easily solubilized. Most of the spermine associated with the chromation is chromatin-specific.
TL;DR: The authors showed that carnation petals, at a stage in which they are already producing ethylene, show a sigmoidal dependency of ethylene production on temperature within the range of 0 to 30°C.
Abstract: Carnation petals, at a stage in which they are already producing ethylene, show a sigmoidal dependency of ethylene production on temperature within the range of 0 to 30°C. An Arrhenius plot of these data show a break atca. 22°C in the straight lines connecting the points. The activity of the ethylene-forming enzyme (EFE), measured bothin vitro, using isolated membranes, andin vivo, using petals pretreated with 1-aminocyclopropane-1-carboxylic acid (ACC), shows an exponential dependency on temperature within the same range. Arrhenius plots of EFE activity fail to show any discontinuity. In contrast, ACC synthase activity measuredin vitro shows the same sigmoidal dependency on temperature as that of the intact petals. We suggest, therefore, that ACC synthase activity is the rate-limiting step mediating the influence of temperature on ethylene biosynthesis by carnation petals over the range studied.
TL;DR: A binding site for auxins was found in the 50,000g pellet from a homogenate of shoots from dark-grown wheat seedlings as mentioned in this paper, and the optimum conditions for the binding of native auxin, IAA, were within the range of physiological conditions of growth (pH 5.2, temperature 20° C).
Abstract: A binding site for auxins was found in the 50,000g pellet from a homogenate of shoots from dark-grown wheat seedlings. The optimum conditions for the binding of native auxin, IAA, were within the range of physiological conditions of growth (pH 5.2, temperature 20° C). The binding site displayed a high affinity to IAA (affinity constant about 107M−1, i.e. dissociation constant about 10−8M) and low capacity, 60 p mol per 1 g of fresh weight. The binding capacity of 3.5-days-old shoots is represented by about 56% and 44% of that of leaves and coleoptiles, respectively. The more rapidly growing leaves also contained more endogenous free IAA (64%) than the coleoptiles from the same seedlings (36%). The binding site was very specific, distinguishing well between strong auxins and structurally related substances which exhibit very weak auxin activity. These physiological properties of this binding site indicate that it may have a certain role in the regulation of physiological processes, such as elongation growth and cell division.
TL;DR: The results suggest that should cytokinins such as zeatin be translocated to mature leaves of this deciduous gymnosperm their export from the leaves would be unlikely unless first metabolised, in all probability the metabolites concerned are cytokinin glucosides.
Abstract: Irrespective of their age, leaves of Ginkgo biloba metabolised applied 8 (14C) zeatin to compounds of similar chromatographic properties. Glucosylation is apparently not a normal feature of cytokinin metabolism in immature leaves. However, the application of zeatin to these leaves did result in the formation of metabolites which co-chromatographed with glucosylated cytokinins. As far as cytokinin metabolism is concerned therefore, this application of excess zeatin allowed immature leaves to behave as mature or senescing leaves. Overall metabolism was fastest in immature leaves. From the metabolites formed it would appear as if oxidation, which resulted in the formation of a metabolite which co-eluted with N-(purin-6-yl)glycine, was also important in immature leaves. In senescing leaves glucosylation was the major form of metabolism. Extraction and re-application of the polar metabolites (formed from zeatin) to mature leaves resulted in the formation of compounds which co-chromatographed with zeatin. This suggests that these compounds could serve as precursors for zeatin or could be hydrolysed to form zeatin.
TL;DR: Normal and virus-infected cells are being studied for their content of phenolic acid amides of the polyamines, and an inhibitor of dicyclohexylamine blocks spermidine synthesis in intact protoplasts, and in so doing stimulates spermine synthesis.
Abstract: Leave of Chinese cabbage from healthy plants or from those infected with turnip yellow mosaic virus yield protoplast which convert methionine to protein, S-adenosylmethionine, decarboxylated S-adenosylmethionine. spermidine, spermine and 1-aminocyclopropane-1-carboxylate. The enzyme spermidine synthase is entirely cytosolic and has been purified extensively. An inhibitor of this enzyme, dicyclohexylamine, blocks spermidine synthesis in intact protoplasts, and in so doing stimulates spermine synthesis. Aminoethoxyvinylglycine blocks the conversion of S-adenosylmethionine to 1-aminocyclopropane-1-carboxylate, the precursor to ethylene, in protoplasts. This inhibitor markedly stimulates the synthesis of both spermidine and spermine. Essentially all the protoplasts obtained from new leaves of plants infected 7 days earlier are infected. On incubation, such protoplasts convert exogenous methionine to viral protein and viral spermidine whose specific radioactivity is twice that of total cell spermidine. Exogeneous spermidine is also converted to cell putrescine and viral spermidine and spermine. Normal and virus-infected cells are being studied for their content of phenolic acid amides of the polyamines.
TL;DR: In this paper, the use of small columns containing charcoal and cellulose for the purification of abscisic acid and its metabolites from plant extracts is described, and the method is shown to be superior to other published methods using commercial pre-packed cartridges.
Abstract: The use of small columns containing charcoal and cellulose for the purification of abscisic acid and its metabolites from plant extracts is described. These columns have high capacity and the sample processing time is short. The efficiencies of recovery of abscisic acid, abscisic acid glucose ester, dihydrophaseic acid and an unidentified highly polar metabolite of abscisic acid are about 90%. The method is shown to be superior to other published methods using commercial pre-packed cartridges.