bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell number, cell size and hormone levels in semi‐isogenic mutants of Lycopersicon pimpinellifolium differing in fruit size
Authors: Bohner Jürgen , Bangerth Fritz
Published: May 2006

Tomato fruit growth parameters, cell number and cell size, and hormone levels [IAA, abscisic acid (ABA), zeatin (Z)/zeatin riboside (ZR), isopentenyladenosine (i‐Ado)/isopentenlyadenine (i‐Ade)], in the wild‐type (Lycopersicon pimpinellifolium Mill.) and a semi‐isogenic mutant (mutant III) differing in fruit size were investigated during fruit development. An image‐processing system was used for the determination of cell number and single cell size per fruit and hormone levels were measured by radioimmuno‐assay (RIA). The bigger fruits of mutant III showed higher cell numbers throughout fruit development and cells enlarged faster than in wild‐type fruits. During the first 10 days of fruit growth, the main cell division period after fertilization, high concentrations of cytokinins were found, these being correlated with high cell division activity. There were only slight differences in IAA and ABA levels in the different sized fruits. The results emphasized the importance of the cell number per fruit at anthesis as a determining factor of final fruit size in tomatoes. A possible relationship between cytokinins and subsequent fruit development is discussed.
Role of carboxylate in the nitrogen metabolism of plants from different natural habitats
Authors: Wollenweber B. , Kinzel H.
Published: May 2006

The carboxylate and organic nitrogen content was studied in plants from 5 different habitats in Austria in order to determine both the form of nitrogen utilized by the plants and the preferential site of nitrate reduction within the plant, if nitrate is the predominant nitrogen form and is reduced mainly in the shoots, the ratio between carboxylate and organic nitrogen should be about 1. Ratios less then 1 would indicate either participation of root reduction, transport of carboxylate from shoots to roots or ammonium/ammonia nutrition.

In the plants investigated, the lowest ratios were found in a bog, where ammonium is usually the predominant nitrogen form. Species from a xerophytic and a nutrient‐rich habitat, as well as from a carr, showed higher organic nitrogen values. Highest contents of carboxylate and organic nitrogen were found in halophytes from the area around the take Neusiedlersee. As additional bicarbonate uptake is known to occur at these sites, accumulation of carboxylate here may not he related to nitrate reduction alone.

The relationship between the carboxylate/organic nitrogen ratio and N indicator values revealed the same pattern of differences in the plant species, indicating that the determination of these values could give information of ecophysiological characteristics of, and differences between, plant species from various habitats.
High yield isolation of mesophyll protoplasts from wheat, barley and rye
Authors: Sarhan Fathey , Cesar Dismie
Published: May 2006

Efficient procedures are described for high‐yield isolation of mesophyll protoplasts from spring wheat (Triticum aestivum L. cv. Glenlea), winter wheat (Triticum aestivum L. cv. Frederick), barley (Hordeum vulgare L. cv. Bruce) and rye (Secale cereale L. cv. Puma). Factors such as plant age, composition of the incubation medium during isolation, purification procedures and culture medium affect protoplast yield, viability and metabolic competence, as measured by light‐dependent CO2 fixation. Optimal osmolarity of the isolation medium was equivalent to 1.8 times that measured in the leaves of all plant material used. The presence of 2 mM ascorbic acid in the preincubation and isolation medium increased the yield by 50% and conserved viability and metabolic competence. The protoplasts were stable for up to 48 h without loss of either viability or of original activity of CO2 fixation, which was in the order of 100 μmol CO2 (mg chl)−1h−1.

In our MC‐56 liquid medium these protoplasts regenerated cell walls within 72 h and a few divided.
Culture of meristem tips and micropropagation of 12 commercial clones of poplar in vitro
Authors: Rutledge Clare B. , Douglas G. C.
Published: May 2006

Twelve commercial clones of poplar were cultured in vitro from meristem lips (0.3–0.5 mm diameter), shoot tips (4–6 mm long) and nodal segments (5–10 mm long). Shoot‐producing cultures were obtained from 4, 32 and 70% of meristem lips, shoot tips and nodal segments within 12, 6 and 4 weeks, respectively. The genotype of cultures had a greater influence on development of shoot‐producing cultures than medium composition. Cultivars Max/Ber and Oxford had the highest rates of establishment in culture and subsequent shoot proliferation, while P. tacamahaca, P. trichocarpa and cv. Robusta exhibited very low rates of establishment and low vigor in vitro. Shoot tip development was best on agar‐solidified medium whereas liquid medium resulted in vitrification. Higher rates of axillary shoot production from established cultures were obtained with benzyladeninc or zeutin than with 2‐isopen‐tenyladenine. deducting the benzyladenine concentration from 4,4 to 1.1 μM, increased the production of elongated shoots suitable for rooting.
Variation of RuBP carboxylase activity among anther‐derived plants of Solanum phureja
Authors: Pehu Eija , Veilleux Richard E. , Servaites Jerome C.
Published: May 2006

The effect of genotype and ploidy on RuBP carboxylase (EC 4.1.1.39) activity, chlorophyll content, leaf area, chloroplast ultrastructure and not photosynthesis among monoploid. diploid and tetraploid anther‐derived plants of Solanum phureja Juz, and Buk. was studied. Within the monoploid group, RuBP carboxylase activity and concentration displayed a significant genotypic effect. For the diploids, variation among genotypes was significant for total protein content and maximum specific activity of RuBP carboxylase, and among the tetraploids for net photosynthesis and specific leaf weight. Ploidy effect was evident regarding net photosynthesis, leaf area and chlorophyll content. The different ploidy groups among the anther‐derived plants surpassed the anther donor plant for all characteristics except maximum activity of RuBP carboxylase and net photosynthesis. For the latter only the tetra‐ploid group was superior to the anther source plant. However, a monoploid genotype with an increase of 9% in maximum activity of RuBP carboxylase over the anther‐donor plant was identified. Segregation of trails rind differential gene expression together with possible mutations during androgenesis are discussed as sources of variation.
Inhibition of adenine nucleotide translocation in maize seedling mitochondria by anionic detergents
Authors: Konstantinov Yury M. , Podsosonny Vladimir A. , Lutsenko Galina N.
Published: May 2006

Low concentrations (50–200 μM) of the anionic detergents cholate, deoxycholate and dodecylsulphate inhibited the activity of adenine nucleotide translocator in mitochondria from etiolated maize (Zea mays L. hybrid Krasnodarskij 303) coleoptiles. This resulted in: (a) a decrease in the rates of oxidative phosphorylation and hydrolysis of extramitochondrial ATP; (b) a decrease in the rate of [33P]‐ATP transport through the inner mitochondrial membrane. Anionic detergents may act as competitive inhibitors of ADP and ATP transport in maize mitochondria.
Metabolic and structural responses of pine buds under climate chamber conditions
Authors: Lindfors Aija , Kupila‐Ahvenniemi Sirkka
Published: May 2006

Scots pine (Pinus sylvetris L.) plants, about 2 m high, were placed in controlled conditions for 2 weeks in January, April and November. During the experiments made in January, the conditions in the climate chambers simulated either a gradual or abrupt advancement of spring. In April they simulated either the advancement of the season or its reversal back to January. In November the plants were transferred to conditions that resembled spring. In January, pieces of buds collected at the end of the experiment were also fixed for electron microscope studies.

Isolation of the ribosomes and the determination of their in vitro translation capacity revealed that in January the response to environmental changes was evident. An increase in synthesized proteins was caused by a rise in the translation capacity of ribosome assemblies rather than by an increase in their quantity. The cellular ultras‐structure changed in conformity with the changes characteristic of the spring. In April, the plants transferred to the climate chambers maintained their ability to synthesize proteins, but the buds were judged to be under stress. In November die ability of the buds to respond to environmental changes was retarded or inhibited.
Growth inhibitors in oat grains. II. Bioassays for characterization of a new substance in leachate of oat hulls (Avena sativa) regulating root growth
Authors: Häggquist M.‐L. , Widell K.‐O. , Fredriksson M. , Liljenberg C.
Published: May 2006

Oat hull leachate, auxin and ethylene cause similar effects on oat (Avena sativa L. cv. Risto) seedlings: inhibited root elongation, swollen roots and extensive root hair formation. Micrographs reveal that the leachate caused a reorientation of the cell expansion in the root from a longitudinal to a radial direction. Dry weights showed that the distribution of nutrients from the endosperm into the seedling was not inhibited, but regulated by the leachate. Tests with Ag+, inhibiting the effects of ethylene, as well as biotests with seeds of Amaranthus caudatus L. cv Mörk Purpur excluded ethylene from being responsible for the morphological changes. Results of growth tests and Avena coleoptile bioassuys indicated that oat hull leachate contains a substance that is not identical with IAA, but mediates the effects of endogenous IAA of the seedling. In a parallell investigation (Häggqquist, M.‐L. et al. 1988. ‐ Physiol. Plant. 72: 423–127) the active substance of an high performance liquid chromatography (HPLC) fraction of the leachate was identified as tryptophan.
Iron‐deficiency in pea leaves: Effect on lipid composition and synthesis
Authors: Abadia A. , Ambard‐Bretteville F. , Remy R. , Trémolièes A.
Published: May 2006

The lipid composition of chlorotic leaves of Pisum sativum L. cv. Kelvedon Wonder, developed under iron‐deficiency was determined and compared to similar material developed under normal nutrient conditions. All lipid classes were affected by iron‐deficiency but to different extents, and thylakoid lipids were more affected than non‐thylakoid lipids. The most striking results concerned changes in the fatty acid content of the main polar lipids. The linolenic acid of the galactolipids decreased to the benefit of more saturated fatty acids, mainly linoleic acid. In phosphatidylglycerol, the proportion of Δ3‐trans‐hexadecenoic acid decreased. Using radioactive acetate, lipid synthesis was investigated. Desaturation leading to linoleic acid was less affected by iron‐deficiency than desaturation leading to Δ3‐trans‐hexadecenoic and linolenic acids.
Nucleotide status and protein synthesis in vivo in the apices of juvenile and mature Sequoiadendron giganteum during budbreak
Authors: Bon Marie‐Claude
Published: May 2006

Adenine and guanine nucleotide contents of isolated apices collected from a juvenile and a mature clone of Sequoiadendron giganteum (Lindl.) Buchholz during budbreak were determined. GDP and GTP contents were significantly higher in the juvenile clone apex than in the mature ones, whereas there was no difference in ATP concentration between the two materials. In vivo, induction of protein synthesis was similar in the two clones after 10 min of [35S]‐methionine labeling. The increase of [35S]‐methionine‐tRNAs and labeled proteins continued up to 30 min for the juvenile clone. They markedly declined for the mature clone after 10 min. Only the diminution of this in vivo protein synthesis was well correlated with a decrease in GTP content.
Distribution of two isoforms of glutamine synthetase in bundle sheath and mesophyll cells of corn leaves
Authors: Yamaya Tomoyuki , Oaks Ann
Published: May 2006

Localization of two isoforms of glutamine synthetase (GS; EC 6.3.1.2) was investigated in different cell types, mesophyll cells and bundle sheath cells, of corn (Zea mays L. var. W64A × W182E) leaves by using ion exchange chrotnatography. In whole leaf extracts, relative activities of GS1 (cytosolic GS) and GS2 (chloroplastic GS) were almost equal. Purified mesophyll protoplasts and bundle sheath strands also showed similar proportions of GS1 and GS2. Methionine sulfoximine (1 mM) enhanced the accumulation of ammonia when mesophyll protoplasts were incubated with nitrite or when bundle sheath strands were incubated with glycine. This clearly indicates a spatial separation of metabolism of NH+4 derived from photorespiration and from reduction of NOJ.
Changes in the nucleotide pools in leaves and buds of tobacco plants upon treatment with 2,4‐dichlorophenoxyacetic acid
Authors: Golebski Waldemar , Meyer Reiner , Wagner Karl G.
Published: May 2006

Tobacco (Nicotiana tabacum L. cv. Samsun) plants were treated once with 2,4‐dichlorophenoxyacetic acid (2,4‐D) at the 8‐leaf stage. The effect of the herbicide on leaf metabolism was followed over 7 days by determination of the ribonucleotide pools, including NAD+, NADP+ and UDP‐sugars, by high‐preformance liquid chromatography. 2,4‐D treatment resulted in large changes in the nucleotide concentrations, the magnitude and sign of which were dependent upon the leafage. The nucleotide pools decreased in the apical tissue, but increased strongly in the mature leaves with the highest relative increase in the oldest leaf tested. The time course of the changes revealed a maximum on day 5 after 2,4‐D treatment. The increase in the adenine nucleotide pools, energy charge and the NADVNADP+ ratio are interpreted to indicate a stress situation. The different responses of young, mature and senescent tissue to the synthetic auxin could reflect their different inherent sensitivity due to the natural auxin gradient.
Mimicry by cytokinin of phytochrome‐regulated inhibition of chloroplast development in etiolated cucumber cotyledons
Authors: Cohen Lila , Arzee Tova , Zilberstein Aviah
Published: May 2006

A study of the kinetics of chlorophyll (Chl) synthesis in cotyledons of etiolated cucumber seedlings (Cucumis sativus L. cv. Delilah) treated with 5×10‐5M ‐ben‐zyladenine (BA) showed that cytokinin, like a red light pulse, could inhibit as well as promote pigment accumulation depending on the length of the dark period following induction. Spraying intact, dark‐grown seedlings with BA, 24 h prior to white light exposure, eliminated the lag phase in Chl synthesis, while treatment with hormone 72 h before greening not only delayed the onset of synthesis, but it also reduced the amount of Chl accumulated after 24 h continuous white light. Impairment of Chl formation was correlated with inhibited regeneration of protochlorophyll and delayed appearance of the light harvesting Chl alb polypeptide. Application of σ‐aminolevulinic acid (15 mM) 2 h before white light exposure shortened the lag phase in Chl synthesis in control as well as in inhibited cotyledons, but the adverse effect of the red light and BA treatments on long‐term Chl accumulation (24 h) was not reversed. Application of glutamate did not stimulate Chl production. Simultaneous treatment with hormone and red light 72 h before greening enhanced their separate inhibitory effects on Chl synthesis, but when given together 24 h prior to white light, their promotive effects on pigment accumulation were not additive.
Glutathione synthetase in tobacco suspension cultures: catalytic properties and localization
Authors: Hell R. , Bergmann L.
Published: May 2006

Glutathione synthetase activity (EC 6.3.2.3) was analysed in ammonium sulfate precipitates of extracts l'rom photohetevotrophically grown cells of Nicotiana tabactm L. cv. Samsun by determination of glutathione as its monobromobimane derivative. Maximal enzyme activity was obtained at pH 8.0–9.0 in Tris‐HCl and CHES as buffer systems. The enzyme showed an absolute requirement for Mg2+ and was slightly stimulated by K+. When Mg2+ was replaced by Mn2+ less synthetase activity was observed, and above 30 mM Mn2+ no activity was found. The enzyme was specific for glycine (KM = 0.308 mM). No product formation was observed with ß‐alanine and γy‐aminobutyrate using substrate conccntrations of 10 mM. The apparent KM values for γ‐glutamylcysteine and γ‐glutamyl‐l‐α‐aminobutyrate were, respectively, 0.022 and 0.033 mM. By chloroplast Isolation ca 24% of the total glutathione synthetase activity of the cells could be shown to be localized in the chloroplasts, the rest being attributed to the cytoplasm of the tobacco cells.
Early changes in morphology and polypeptide pattern of plastids from watermelon cotyledons induced by benzyladenine or light are very similar
Authors: Bracale Marcella , Longo Giovanna P. , Rossi Gianfranca , Longo Claudio P.
Published: May 2006

Watermelon (Citrullus vulgarisSchrad. cv. Fairfax) cotyledons were excised from the embryo and grown in the dark for 4 days. They were then transferred to 10 μm benzyladenine (BA) solution or illuminated with white light. We have compared changes in ultrastructure of the plastids and of their polypeptide pattern induced by the two treatments.

At the end of the 4‐day‐period in the dark the plastids differentiated to amyloplasts and had few polypeptides: only the two subunits of ribulose bisphosphate carboxylase (RuBP) were clearly observed. Both light and BA induced starch depletion and gratia formation after 12–24 h. BA was less efficient than light in inducing thylakoid formation and more efficient in inducing starch depletion. After 6 h both factors induced the appearance of the same new polypeptides in the 28–53 kDa range. Most prominent among them is a 32 kDa band. Light is much more effective in inducing the formation of a 29 kDa band than is BA. In mature chloroplasts this band stains very strongly, while the 32 kDa band disappears. We suggest that the 29 kDa polypeptide is the light harvesting complex (LHC), since a purified LHC preparation from cotyledons grown either on water in light or on BA in the dark migrates on the polyacrylamide gel as a single 29 kDa band.
Alteration of the synthesis of lipoxygenase in the early stages of soybean cotyledon culture
Authors: Wang Xuemin , Bookjans Gerhard , Altschuler Mitch , Collins Glenn B. , Hildebrand David F.
Published: May 2006

A detailed study of lipoxygenase (EC 1.13.11.12) synthesis in cotyledons of soybean [Glycine max (L.) Merr. cv. Century] cultured in vitro for up to 40 h showed that synthesis of this protein, measured by in vivo [35S]‐methionine labelling in connection with immunological methods and cell‐free translation of mRNA, underwent a large transient reduction in the first 4 h of culturing and gradually increased in the following 36 h. Northern blot hybridizations with lipoxygenase cDNA clones showed that the decrease in translational activity was the consequence of a considerable reduction in lipoxygenase mRNA in the cotyledons. From these results we conclude that the transient decline in lipoxygenase synthesis in excised soybean cotyledons is regulated at the RNA level. Similarly judged from the analysis of patterns of uni‐dimensional gel electrophoresis, the synthesis of a few other polypeptides decreased during the first 4 h of culture as well, while several others increased; in cotyledons cultured for 20 to 40 h the protein‐synthesis pattern had returned to that in freshly excised cotyledons. An acclimation period of ca 1 day seems to be needed for isolated soybean cotyledons to stabilize and to resume regular RNA and protein synthesis.
Nucleotide sequence of the single ribosomal RNA operon of pea chloroplast DNA
Authors: Stummann B. M. , Lehmbeck J. , Bookjans G. , Henningsen K. W.
Published: May 2006

The nucleotide sequence of an 8 kbp region of pea (Pisum sativum L.) chloroplast DNA containing the rRNA operon and putative promoter sites has been determined and compared to the corresponding sequences from maize, tobacco and the liverwort Marchantia polymorpha. The chloroplast DNA species of all vascular plants investigated, with the exception of a few legumes including pea, and of Marchantia contain an inverted repeat with an rRNA operon. The pea rRNA operon is the first sequenced rRNA operon from a plant with only one copy of the rRNA genes per molecule of chloroplast DNA. The organization of the operon is the same as for maize, tobacco and Marchantia. i.e. tRNA‐Val gene/16S rRNA gene/spacer with intron‐containing genes for tRNA‐Ile and tRNA‐Ala/23S rRNA gene/4.5S rRNA gene/5S rRNA gene. Current evidence suggests that the tRNA‐Val gene may not be contranscribed with the other genes. For pea 16S, 23S, 4.5S and 5S rRNA have 1488, 2813, 105 and 121 nucleotides, respectively. The homologies of the entire operon (the tRNA‐Val gene ‐ 5S rRNA region) to those from tobacco, maize and Marchantia are 88, 82 and 79%, respectively. The corresponding homologies for tobacco/maize, tobacco/Marchantia and maize/Marchantia have similar values. The 16S and 23S rRNA genes from pea are more than 90% homologous to those from the 3 other species. We conclude that the fact that pea only has one set of rRNA genes per molecule of chloroplast DNA is apparently not correlated with any significant difference between the pea operon and the rRNA operons from tobacco, maize and Marchantia.
Effects of lithium ions on the circumnutations of Helianthus hypocotyls
Authors: Zachariassen Eli , Johnsson Anders
Published: May 2006

The influence of Li+ on the circumnutations of hypocotyls of Helianthus annuus L. cv. Californicus was investigated. LiCl at concentration levels from 0 to 40 mM (lethal) was added to intact hypocotyls grown in liquid nutrient medium. The Li+ concentration in the hypocotyls was measured by flame photometry. The growth of the hypocotyls was not affected by the LiCl.

Amplitude and frequency of the circumnutations were determined by correlation analysis. The oscillatory pattern of the movements became less regular at concentrations above 10 mM LiCl. The amplitude of the movements was reduced for concentrations above 7 mM LiCl. The frequency of the movements was reduced when LiCl was increased from 0 to 10 mM. Above 10 mM LiCl the frequency of the circumnutations was higher than for control plants. The results showed that circumnutations of sunflower hypocotyls can be added to the group of oscillators in biological organisms that are affected by Li+.
The polypeptide composition of highly purified prolamellar bodies and prothylakoids from wheat (Triticum aestivum) as revealed by silver staining
Authors: Lindsten Agneta , Ryberg Margareta , Sundqvist Christer
Published: May 2006

The inner membranes from wheat (Triticum aestivumL. cv. Walde, Weibull) etioplasts were separated by density centrifugation. The etioplasts were broken by osmotic shock and the inner membranes were split by the sheering forces when pressed through a syringe needle. Membrane fractions representative of prolamellar bodies and prothylakoids, respectively, were achieved by separation on a 20–50% continuous sucrose density gradient followed by different purification procedures. The membrane contents of the isolated fractions were characterized by low temperature fluorescence spectra, sodium dodecyl sulphate polyacrylamide gel electrophoresis and electron micrographs. The prolamellar body and the prothylakoid fractions had a fluorescence emission ratio 657/633 nm of 18 and 0.9, respectively. The main part of the total amount of PChlide was found in the prolamellar body fraction. The electrophoretograms stained with Coomassie Blue showed the presence of mainly two polypeptides. The NADPH‐protochlorophyllide oxidoreductase was the dominating polypeptide in the prolamellar body fraction, and the α and β subunits of the coupling factor 1 of chloroplast ATP synthase the dominating polypeptides in the prothylakoid fraction. Silver staining revealed at least 4 additional prominent bands with molecular weights of 86, 66, 34 and 28 kDa. The polypeptide composition of the prolamellar body is thus more complex than earlier judged after Coomassie Blue staining. The function of these polypeptides is unknown, but the knowledge of their presence is important in understanding the formation and function of the prolamellar body.
Modelling the relative growth rate as a function of plant nitrogen concentration
Authors: Hirose Tadaki
Published: May 2006

The relationship between the relative growth rate (RGR) and the nitrogen concentration of the whole plant (PNC) was analyzed by using experimentally determined relations (1) between the PNC and the fraction of dry matter (LWR) and nitrogen in leaves, (2) between the specific leaf area (SLA) and the leaf nitrogen concentration (LNC) and (3) between the net assimilation rate (NAR) and the LNC on an area basis. A strong dependence of RGR on nitrogen concentration resulted from the increase in NAR, LWR and SLA with increasing PNC. A curvilinear relationship between RGR and PNC gave an optimum curve for nitrogen productivity against PNC.
Exodermal Casparian bands: their significance for ion uptake by roots
Authors: Peterson Carol A.
Published: May 2006

The roots of many angiosperm species possess two Casparian bands, one in the endodermis and one in the outermost layer of the cortex. Over most of the root surface in these species, ions are taken up by the epidermis and may be transported symplastically to the xylem.
The roles of carbon dioxide and abscisic acid in the production of ethylene
Authors: Tan  , Zhi‐Yi  , Thimann Kenneth V.
Published: May 2006

Since CO2 is liberated in the conversion of ACC to ethylene, the evidence that ethylene production by plant tissues is actually promoted by CO2 calls for an explanation. Accordingly, the formation of ethylene by oat (Avena sativa L. cv. Victory) leaves and by apple (Golden Delicious) and pear (Pyrus communis L. cv. Anjou) tissue in very low levels of CO2 has been studied. The gas chromatograph was modified to measure CO2 and ethylene at the same time, by reducing both to methane. (Response of the gas chromatograph to CO2 concentrations is linear.) The work establishes a clear difference between the endogenous production of ethylene and its production from applied ACC, a difference which holds about equally for leaves and for fruit tissue. The difference is in the CO2 requirement, namely, lowering the CO2 level by 99% or more decreases the production of ethylene from applied ACC by 50–60%, but it does not decrease, or even slightly increases, its production from endogenous precursors. Thus, while the need for CO2 has not been explained, it has at least been delimited.

The responses to abscisic acid (ABA) also differ, but in the reverse direction, the endogenous production of ethylene being decreased up to 70% by ABA. while the liberation from ACC is promoted about 20%. ABA also promoted the respiratory CO2 production by 30% or, in presence of 1‐aminocyclopropane‐1‐carboxylic acid (ACC), by over 50%. Inhibition of ethylene production by cobalt or EDTA shows no such differentiation, while inhibition by Na catechol‐4,6‐disulfonate (Tiron) shows a small difference. It is concluded either that endogenous ethylene is formed by an enzyme system different from that reacting with ACC, or (more likely) that when ethylene arises from endogenous precursors the reaction does not proceed by way of free ACC, but by some activated form of it.
Determination of ornithine, putrescine, N‐methylputrescine and N‐methylpyrroline pools in tobacco tissue by high‐performance liquid chromatography
Authors: Feth Friedhelm , Wagner Karl G.
Published: May 2006

A procedure for the determination of metabolites of the biochemical pathway ornithine to N‐methyl‐δ1‐pyrrolinium salt (N‐methylpyrroline) is described. Plant tissue was extracted with 0.5MHCl and the extract purified on C18‐cartridges. Ornithine was reacted witho‐phthaldialdehyde, putrescine and N‐methylputrescine with dansyl chloride and the products were separated by reversed‐phase high‐performance liquid chromatography (HPLC). N‐methylpyrroline was determined by cation‐exchange HPLC without derivatization. The metabolites in the roots of tobacco (Nicotiana) species with different nicotine‐producing capacities were determined. Furthermore, the specific activities of the enzymes ornithine decarboxylase (EC 4.1.1.17), putrescine N‐methyltransferase (EC 2.1.1.53) and N‐methylputrescine oxidase were determined. Both the metabolite pools and the enzyme activities were correlated with the different nicotine‐producing capacities of the different tobacco species.
Stimulation of ATPase activity in barley (Hordeum vulgare) root plasma membranes after treatment with triacontanol and calmodulin
Authors: Lesniak Andrew P. , Haug Alfred , Ries Stanley K.
Published: May 2006

Triacontanol (TRIA) treatment of plasma membrane‐enriched vesicles from barley (Hordeum vulgare L., cv. Conquest) roots resulted in stimulation of membrane‐associated, divalent cation‐dependent ATPase activity (EC 3.6.1.3). The stimulation at physiologically active concentrations of TRIA (10−11–10−9M) occurred only when the vesicles were treated with TRIA in the presence of calmodulin. Octacosanol, the C28‐analogue of TRIA, had no effect on divalent cation‐dependent ATPase activity. Consistent with in vivo studies, simultaneous treatment of vesicles with weight equivalents of TRIA and octacosanol reduced the stimulation of ATPase activity. The effect of calmodulin on the stimulation of ATPase activity was diminished by calmidazolium, a specific inhibitor of calmodulin. Circular dichroism studies did not show a change in the α‐helix content of calmodulin in the presence of TRIA. TRIA also had no apparent effect on soluble calcium‐calmodulin 3′,5′‐cyclic nucleotide phosphodiesterase activity. Removal of excess TRIA from the medium after treatment still resulted in stimulation of divalent cation‐dependent ATPase activity in the presence of calmodulin was comparable to treated vesicles from which excess TRIA had not been removed. These data further support the contention that TRIA affects membrane structure and function.
IAA‐induced adventitious root formation in greenwood cuttings of Populus tremula and formation of 2‐indolone‐3‐acetylaspartic acid, a new metabolite of exogeneously applied indole‐3‐acetic acid
Authors: Plüss Raphael , Jenny Titus , Meier Hans
Published: May 2006

When indole‐3‐acetic acid (IAA) is applied through the basal cut surface of greenwood cuttings from Populus tremula L. with the aim to induce adventitious roots, it is observed that a positive correlation between the number of new roots and the duration of the application exists only for the first 5 to 6 hours. This is most likely due to the induction, during this time, of a metabolic system that transforms IAA to compounds unable to provoke new roots. The most important of these compounds was identified as 2‐indolone‐3‐acetylaspartic acid (OxlAasp). The metabolic pathway from IAA to OxIAasp via indole‐3‐acetylaspartic acid was demonstrated by thin layer chromatography.
Thermoluminescence in plants
Authors: Demeter S. , Govindjee
Published: May 2006

Recently considerable progress has been achieved in the elucidation of the origin of thermoluminescence in chloroplasts. The assignment of 2 of the thermoluminescence bands, peaking at around +5°C (Q or D band) and +30°C (B band), to the recombination of charges, originating from the oxidzed species of the oxygen evolving complex (the so‐called S states) and to the reduced primary and secondary quinone acceptors QAand QB, respectively, has aided in the investigation of reactions involving both the electron donor and acceptor sides of photosystem II. In this paper we review recent thermoluminescence results concerning the deactivation of S states, temperature and pH dependence of S state transition, and the activity of the water oxidizing system after removal of Cl−, manganese or the 33 kDa protein. Reports on the use of thermoluminescence in investigations on the sites of action of herbicides and redox changes of QBconferred by herbicide resistance are also discussed. The effect of pH, bicarbonate, and Acceleration of Deactivation Reaction of enzyme “Y” (ADRY) reagents on the photosystem II reactions are presented in the light of thermoluminescence observations. Further possible applications of thermoluminescence promising better understanding of the photosynthetic processes are suggested.
Carbohydrate, protein and amino acid status of Glycine‐Glomus‐Bradyrhizobium symbioses
Authors: Pacovsky Raymond S.
Published: May 2006

Soybean [Glycine max (L.) Merr. cv. Amsoy 71] plants were inoculated with either the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum, with a strain of Bradyrhizobium japonicum. or with both endophytes together. Non‐inoculated plants were fertilized with levels of N and P that resulted in plant growth similar to that following infection by Bradyrhizobium or Glomus, respectively. In general, plants colonized by Glomus contained more pinitol (1d‐3‐O‐methyl‐chiro‐inositol) but less starch than corresponding P‐fertilized soybeans, while nodulated soybeans contained more pinitol and sucrose in the roots than corresponding N‐fertilized plants. Compared to nutrient‐amended soybeans, increases or decreases in free amino acids in symbiotically grown plants tended to follow transient changes in N content and endophyte activity. The exception to this was the elevated levels of methionine in nodulated roots or aspartate and arginine in Glomus‐inoculated roots regardless of N level. There were both quantitative and qualitative changes in the proteins found in inoculated soybeans, especially in infected roots where nodulins (nodule‐specific proteins) and endomycorrhizins (mycorrhiza‐specific proteins) were detected by polyacrylamide gel eletrophoresis. Five nodulins (11.8% of root proteins) were detected with molecular weights of 14, 34, 40, 41 and 100 kDa. Five endomycorrhizins (5.1% of root proteins) were detected with molecular weights of 16, 17, 18, 22 and 30 kDa. Differences in nutrient uptake and allocation in symbiotic plants could not be duplicated by fertilizer input alone, although nutrient addition could lead to similar growth rates and dry weight accumulation. These findings suggest that the quality and quantity of plant carbohydrates, proteins and amino acids shift in response to the physiological changes resulting from infection by N2‐fixing bacteria or endomycorrhizal fungi.
Immunoaffinity columns for isolation of abscisic acid in conifer seedlings
Authors: Kannangara T. , Wieczorek A. , Lavender D. P.
Published: May 2006

Spleen cells of mice immunized with cis, trans (±) abscisic acid (ABA) conjugated to bovine serum albumin (BSA) were fused with myeloma cells to produce hybridomas. Hybridomas secreting antibodies to cis, trans (+) ABA were detected by enzyme‐linked immunoassay and injected into the peritoneal cavity of mice to produce ascites fluid. Antibodies purified by size‐exclusion chromatography were linked to cyanogen bromide‐activated Sepharose beads and used to prepare immunoaffinity columns (IAC). Semi‐purified conifer seedling (Douglas‐fir [Pseudotsuga menziesii (Mirb) Franco] lodgepole pine (Pinus contorta Dougl), cedar (Thuja plicata D. Don), and spruce [Picea glauca (Moench) Voss)]) extracts were passed through IAC, washed thoroughly with water and then eluted with methanol. ABA in the methanol eluate was analysed by high performance liquid chromatography with UV detection. UV absorption of extracts before and after purification through IAC indicated an excellent purification of extract by IAC. The identity of the ABA peak was confirmed by gas chromatography‐mass spectrometry.
Subchloroplast localization of polypeptides synthesized by chloroplasts during senescence
Authors: Guéra Alfredo , Martin Mercedes , Sabater Bartolomé
Published: May 2006

To study the localization of polypeptides synthesized by isolated senescent chloroplasts we have fractionated the chloroplasts into stroma, envelope and thylakoid components. The validity of the fractionation procedure was tested by assaying both chlorophyll and enzyme markers, as well as the polypeptide composition of each fraction. Plastids in the transition of etioplast to chloroplast, senescent chloroplasts and kinetin‐treated chloroplasts produced acceptable fractions, although their polypeptide compositions varied considerably during the ontogeny, particularly those of the envelope. Most of the polypeptides synthesized by isolated senescent chloroplasts were incorporated into the thylakoids except for a 58 kDa polypeptide localized in the stroma and some minor polypeptides present in both stroma and envelope. Although most of the polypeptides synthesized by isolated chloroplasts from kinetin‐treated leaves were incorporated into the thylakoid membrane, several polypeptides were found in the stroma (90, 80, 65 and 54 kDa) and in the envelope (100, 75, 48 and 28–30 kDa). The results indicate that early in senescence, the polypeptides of the envelope change but, that probably, most of the new polypeptides are synthesized in the cytoplasm.
The role of light and CO2 in optimising the conditions for shoot proliferation of Actinidia deliciosa in vitro
Authors: Infante R. , Magnanini E. , Righetti B.
Published: May 2006

Proliferating cultures of Actinidia deliciosa A. Chev., C. F. Liang and A. R. Ferguson cv. Tomuri (♂) were grown under photosynthetic photon flux density (PPFD) rates ranging from 30 to 250 μmol m−2 s−1 in order to determine certain physiological parameters in vitro: CO2 evolution, photosynthesis at three CO2 atmospheric concentrations (330, 1450 and 4500 μl l−1), fresh and dry matter accumulation and proliferation rate.

A proportional response in dry weight, dry/fresh weight ratios and PPFD was found. The proliferation rate increased up to 120 μmol m−2 s−1 but decreased at higher rates. At the highest PPFD, the CO2 released from cultures and accumulated in the vessels reached 200 μl l−1 of; at the lowest rate the CO2 concentration reached 10500 μl l−1 after 28 days of culture. The photosynthetic rate at 1450 and 4500 μl l−1 of CO2 was nearly 4 times higher than at the lowest concentration tested.
The effects of ultraviolet‐B radiation on loblolly pine. I. Growth, photosynthesis and pigment production in greenhouse‐grown seedlings
Authors: Sullivan Joe H. , Teramura Alan H.
Published: May 2006

One‐year old loblolly pine (Pinus taeda L.) seedlings were grown in an unshaded greenhouse for 7 months under 4 levels of ultraviolet‐B (UV‐B) radiation simulating stratospheric ozone reductions of 16, 25 and 40% and included a control with no UV‐B radiation. Periodic measurements were made of growth and gas exchange characteristics and needle chlorophyll and UV‐B‐absorbing‐compound concentrations. The effectiveness of UV‐B radiation on seedling growth and physiology varied with the UV‐B irradiance level. Seedlings receiving the lowest supplemental UV‐B irradiance showed reductions in growth and photosynthetic capacity after only 1 month of irradiation. These reductions persisted and resulted in lower biomass production, while no increases in UV‐B‐absorbing compounds in needles were observed. Seedlings receiving UV‐B radiation which simulated a 25% stratospheric ozone reduction showed an increase in UV‐B‐absorbing‐compound concentrations after 6 months, which paralleled a recovery in photosynthesis and growth after an initial decrease in these characteristics. The seedlings grown at the highest UV‐B irradiance (40% stratospheric ozone reduction) showed a more rapid increase in the concentration of UV‐B‐absorbing compounds and no effects of UV‐B radiation on growth or photosynthetic capacity until after 4 months at this irradiance. Changes in photosynthetic capacity were probably the result of direct effects on light‐dependent processes, since no effects were observed on either needle chlorophyll concentrations or stomatal conductance. Further studies are necessary to determine whether these responses persist and accumulate over subsequent years.
Putrescine uptake and translocation in higher plants
Authors: Rabiti Anna Laura , Pistocchi Rossella , Bagni Nello
Published: May 2006

Putrescine uptake and translocation were studied by feeding [3H] putrescine to roots of tomato seedlings (Lycopersicon esculentum Miller, cv. Earlypak 7) at the stage of expanded cotyledons, of maize seedlings (Zea mais L.) at the coleoptile stage, and of one year old pines (Pinus pinea L.). Putrescine translocation was rapid as radioactivity appeared in the upper part of the seedlings within 30 min, continuing to increase up to 24 h, while it decreased in roots. The putrescine supplied was partly metabolized to spermidine and spermine in the course of 24 h. The transport was temperature‐dependent as it increased with increasing temperature from 4°C to 30°C. In plants kept in 100% relative humidity the transport decreased by 27% compared to controls kept in 50% relative humidity. The existence of basipetal transport was assessed by feeding labeled putrescine to cotyledons or to a primary leaf of tomato plants at different stages of growth. The influence of ringing at the hypocotyl level on polyamine translocation in pine plants was studied in order to exclude cortical parenchyma and phloem from transport. Radioactivity decreased in the hypocotyl just above the ring and in the upper parts (epicotyls with needles), but long‐distance transport was low affected indicating xylem transport. It is suggested that polyamine transport is not polar, and that it occurs mainly through xylem vessels.
Formation of stress ethylene depends both on ACC synthesis and on the activity of free radical‐generating system
Authors: Kacperska Alina , Kubacka‐Zębalska Maria
Published: May 2006

Leaves of soybean (Glyxine max. L., var. Progress) were subjected to desiccation, which brought about varying degree of membrane damage as checked with the conductivity method. Progress of injury up to 30% was associated with promotion of ethylene synthesis and with accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and 1‐(malonylamino)cyclopropane‐l‐carboxylic acid (MACC) in the cells, as well as with activation of lipoxygenase, the enzyme which is involved in lipid peroxidation and which is capable of forming activated oxygen. The stress‐induced promotion of ethylene synthesis was inhibited by the ACC synthase inhibitor aminooxyacetate (AOA). as well as by n‐propyl gallate (PG), a free radical scavenger and inhibitor of lipoxygenase. Pretreatment of non‐stressed soybean leaves with different concentrations of PG also resulted in the corresponding inhibition of lipoxygenase activity and ethylene formation, the former effect being less pronounced than the latter one. In the tissues pretreated with propyl gallate, the ACC level was not affected, whereas the MACC substantially increased. In leaves showing 40% membrane damage neither lipoxygenase activity nor ethylene synthesis increased any further, despite a further increase in the ACC and MACC levels. Therefore, we propose that there are two prerequisites for effective in vivo synthesis of stress ethylene: promotion of ACC synthesis and activation of a free radical‐generating system, which is responsible for the non‐enzymatic conversion of ACC to ethylene. The latter effect seems to be due to the activation of the membrane‐associated lipoxygenase, which depends on stress‐induced alterations in membrane properties.
Uptake of Cd2+ and Fe2+ by excised roots of Tamarix aphylla
Authors: Hagemeyer Jürgen , Waisel Yoav
Published: May 2006

The uptake of Cd2+ by excised roots of Tamarix aphylla (L.) Karst, was investigated using roots of hydroponically grown plants. The concentration isotherm of Cd2+ uptake approached saturation with a single phase hyperbola. The time course of Cd2+ absorption was generally hyperbolic, with an apparent linear section between 2 and 30 min. The temperature response varied among different temperature ranges: a Q10 of approximately 1.9 was found between 10 and 20°C, but at higher and lower temperatures Q10 values were only 1–1.3. It is concluded that Cd2+ uptake by the roots of T. aphylla at moderate temperatures is mediated by a metabolic process, combined with a passive influx component that becomes dominant at higher and lower temperatures. The distribution of the absorption sites for Cd2+ and for Fe2+ along the roots of T. aphylla was also investigated. Cadmium uptake showed no apparent pattern, whereas a distinct pattern of uptake was observed for Fe2+, with the highest rates at the root tip. Iron absorption was stimulated in the presence of nutrients, whereas that of Cd2+ was inhibited. Adsorption and absorption of Cd2+ were strongly inhibited by Ca2+ and by Mg2+, but were unaffected by Fe2+. Monovalent ions (Na+, K+, Li+) also reduced Cd2+ absorption, but to a lesser extent than Ca2+ and Mg2+. Uptake of Cd+ was reduced at lower pH of the medium. The importance of interfering cations for Cd2+ tolerance of T. aphylla is emphasized.
Regulation of assimilation and senescence by the fruit in monocarpic plants
Authors: Noodén L. D. , Guiamét J. J.
Published: May 2006

For most monocarpic species studied, blocking fruit development prevents or at least delays the death of the plants. However, it usually does not prevent the decline in photosynthetic rate, while it may or may not maintain the photosynthetic components (machinery) such as chlorophyll and ribulose 1,5‐bisphosphate carboxylase. Since sink demand influences photosynthetic rate and the fruit‐less plants have limited sink capacity, their reduced photosynthesis may represent a metabolic adjustment but not senescence. The exact causes of the variable decreases in photosynthetic components in fruit‐less plants are uncertain. The causes of metabolic decline may be different in reproductive‐phase monocarpic plants with and without fruit. In any case, assimilation rate, i.e. photosynthesis, may not always provide a reliable index of senescence. Whether or not the developing fruits of monocarpic plants actually control the early and intermediate decline of metabolism is not clear; however, at least in soybean under non‐stress conditions, they cause the final decrease and death.
Critical examination of the quantitative evidence for and against photosynthetic CO2 fixation by guard cells
Authors: Outlaw William H.
Published: May 2006

The evidence for and against photosynthetic CO2 fixation by guard cells is described and critically evaluated. There is a large body of literature on this subject, including enzyme activity assays, immunological assays for ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) in extracts, in situ immunological indicators at the light‐and electron‐microscope levels. products of 14CO2 fixation, and indirect indications such as the effect of light on the P‐glycerate pool size, chlorophyll a (Chi a) flourescence transients, and alkalinization of medium. Although it is not possible to reconcile all the literature, I show that most reports indicate that the photosynthetic carbon‐reduction pathway is absent in guard cells or, at most, does not exceed about 5% of that in mesophyll cells on a Chl basis. Because a mesophyll cell contains approximately 30 times more Chl than a guard cell does, the reported level of the pathway is equivalent to ?0.1 to 0.2% mesophyll contamination, of which it is difficult to ensure the absence. Even if present at these levels, the pathway would not contribute significantly to carbon metabolism.