bluuebunny/crossref_metadata_2025_split huggingface dataset:
Jasmonates, New Regulators of Plant Growth and Development: Many Facts and Few Hypotheses on their Actions
Authors: Parthier B. 
Published: February 2014

AbstractJasmonates, ubiquitous cyclopentanone compounds, are reviewed as new regulators for plant growth and development. They may complement the group of well‐established “classic” phytohormones. Jasmonates influence a multiplicity of plant physiological processes by inhibition, promotion or induction. In many aspects they are similar to abscisic acid, especially in responses to stress. The review contains information on the chemical structures and metabolism of jasmonates, contributes to their biological role and describes possible mode(s) of action at the level of molecular biology and gene expression. In particular, emphasis is placed on the gene expression and accumulation of jasmonate‐induced abundant polypeptides as a stress response of the plant cells. A hypothesis is attempted in which endogenous jasmonates represent an integral part of the signal transduction chain between stress signal(s) and stress response(s).
Osmotic Biosensors. How to Use a Characean Internode for Measuring the Alcohol Content of Beer
Authors: Rüdinger M. , Hierling P. , Steudle E. 
Published: February 2014

AbstractIsolated internodes of Chara corallina and Nitella flexilis have been used to determine the concentration of one passively permeating solute in the presence of non‐permeating solutes. The technique was based on the fact that the shape of the peaks of the biphasic responses of cell turgor (as measured in a conventional way using the cell pressure probe) depended on the concentration and composition of the solution and on the permeability and reflection coefficients of the solutes. Peak sizes were proportional to the concentration of the permeating solute applied to the cell. Thus, using the selective properties of the cell membrane as the sensing element and changes of turgor pressure as the physical signal, plant cells have been used as a new type of biosensor based on osmotic principles. Upon applying osmotic solutions, the responses of cell turgor (P) exactly followed the P(t) curves predicted from the theory based on the linear force/flow relations of irreversible thermodynamics. The complete agreement between theory and experiment was demonstrated by comparing measured curves with those obtained by either numerically solving the differential equations for volume (water) and solute flow or by using an explicit solution of the equations. The explicit solution neglected the solvent drag which was shown to be negligible to a very good approximation. Different kinds of local beers (regular and de‐alcoholized) were used as test solutions to apply the system for measuring concentrations of ethanol. The results showed a very good agreement between alcohol concentrations measured by the sensor technique and those obtained from conventional techniques (enzymatic determination using alcohol dehydrogenase or from measurement of the density and refraction index of beer). However, with beer as the test solution, the characean internodes did show irreversible changes of the transport properties of the membranes leading to a shift in the responses when cells were treated for longer than 1 h with diluted beer. The accuracy and sensitivity of the osmotic biosensor technique as well as its possible applications are discussed.
Autumn Leaves of Ginkgo biloba L.: Optical Properties, Pigments and Optical Brighteners
Authors: Matile Ph. , Flach Barbara M.‐P. , Eller B. M. 
Published: February 2014

AbstractSenescent leaves of Gingko biloba accumulate fluorescent compounds which may contribute to the golden luminous appearance of the autumnal foliage. Apart from the putative effect of such optical brighteners, the changes of spectral optical properties associated with senescence are due to the breakdown of chlorophyll in conjunction with a remarkably high retention of carotenoids. Carotenoid esters accumulate concomitant with chlorophyll breakdown. Optical properties in the infrared range of the spectrum illustrate the intactness of leaf tissue to the end of the senescence period.
Production of the Phytoalexin Glyceollin I by Soybean Roots in Response to Symbiotic and Pathogenic Infection
Authors: Schmidt Petra E. , Parniske M. , Werner D. 
Published: February 2014

AbstractThe amount of the phytoalexin glyceollin I in root exudate and root hairs of individual seedlings of Glycine max (L. Merr. cv. Preston) was analysed using a radioimmunoassay. Bradyrhizobium japonicum 110spc4, which is able to form nitrogen fixing nodules with this plant, caused an increase of up to 50‐fold in glyceollin I levels in root exudate relative to uninfected control seedlings. Maximum glyceollin I levels were reached within 10 h of incubation. Elevated glyceollin I levels were also observed after incubation of soybean roots in sterile bacterial supernatant, a suspension of autoclaved bacteria or the supernatant from broken cells of Bradyrhizobium japonicum. Increased glyceollin I production is not due to the process of active root hair penetration by the microsymbiont since living bacterial cells are not necessary for the induction. The observed glyceollin I production in response to Bradyrhizobium japonicum is several times lower than that after pathogenic infection. Infection with zoospores of the phytopathogenic oomycete, Phytophthora megasperma f. sp. glycinea race 1, leads within 20 h to an accumulation of 7 nmol glyceollin I/seedling in the root exudate of the compatible cultivar Kenwood and 48 nmol glyceollin I/seedlings in that of the incompatible cultivar Maple Arrow. These results support the idea that phytoalexins are implicated in determination of compatibility in pathogenic interactions. Crude cell extracts of different symbiotic bacteria (Bradyrhizobium japonicum 110spc4, Rhizobium meliloti 2011, Rhizobium leguminosarum PRE 8, Sinorhizobium fredii HH 103) were found to induce different amounts of glyceollin I in the root exudate. The observed glyceollin I levels could not be correlated with the ability of these rhizobial strains to nodulate Glycine max. Inhibition of flavonoid and phytoalexin synthesis by (R)‐(1‐amino‐2‐phenylethyl)phosphonic acid (APEP), a specific inhibitor of the phenylalanine‐ammonia‐lyase (PAL), during the first 20 h of the symbiotic interaction dramatically decreased the number of nodules formed in root regions that had been in contact with the inhibitor. This effect was observed at concentrations that inhibited neither bacterial nor plant growth. The implications of these findings for the process of nodule initation are discussed.
Changes in the Ultrastructure of Prasiola crispa ssp. antarctica under Salinity Stress
Authors: Jacob A. , Lehmann H. , Kirst G. O. , Wiencke Chr 
Published: February 2014

AbstractThe supralittoral green alga Prasiola crispa, collected in Antarctica, was grown at salinities ranging from 0.35 %o to 175 %o. Its ultrastructure was examined by electron microscopy and compared with the ultrastructure of plants grown under standard conditions (35 %o).The thalli had very thick cell walls, making up approximately 50% of the thallus volume. Most of the protoplast was occupied by a single chloroplast. Numerous starch granules in the chloroplast were enlarged under hypo‐osmotic conditions and reduced in volume when subjected to hyperosmotic stress indicating a metabolic shift towards low molecular weight organic osmolytes under the latter conditions. Whilst vacuoles were lacking in plants cultured at salinities between 0.35 %o and 35 %o, they developed under hyperosmotic conditions and possibly may serve as compartments accumulating inorganic ions.Growth, photosynthesis and dark respiration were strongly inhibited under higher salinities, whilst they remained almost unaffected under lower salinities (Jacob et al., 1991).
Developmental Changes in the Anatomy of the Sugarcane Stem in Relation to Phloem Unloading and Sucrose Storage
Authors: Jacobsen Karin Ruth , Fisher D. G. , Maretzki A. , Moore P. H. 
Published: February 2014

AbstractTransverse sections of immature and mature sugarcane internodes were investigated anatomically with white and fluorescence light microscopy. The pattern of lignification and suberization was tested histo‐chemically. Lignification began in the xylem of vascular bundles and progressed through the sclerenchymatic bundle sheath into the storage parenchyma. Suberization began in parenchyma cells adjacent to vascular bundle sheaths and spread to the storage parenchyma and outer sheath cells. In mature internodes most of the storage parenchyma was lignified and suberized to a significant degree, except in portions of walls of isolated cells. The pattern of increasing lignification and suberization in maturing internodes more or less paralleled an increase of sucrose in stem tissue. In mature internodes having a high sucrose concentration, the vascular tissue was surrounded by thick‐walled, lignified and suberized sclerenchyma cells. The apoplastic tracer dyes triso‐dium 3‐hydroxy‐5,8,10‐pyrenetrisulfonate (PTS) and amido black 10 B, fed into cut ends of the stalk, wereconfined to the vascular bundles in all internodes above the one that was cut — with no dye apparently in storage parenchyma tissue. Thus both structural and experimental evidence is consistent with vascular tissue being increasingly isolated from the storage parenchyma as maturation of the tissue proceeds. We conclude that in mature internodes the pathway for sugars from the phloem to the storage parenchyma is symplastic. The data suggest that an increasingly greater role for a symplastic pathway of sugar transfer occurs as the tissue undergoes lignification/suberization.
The Control of Lateral Root Development in Cultured Pea Seedlings. II. Root Fasciation Induced by Auxin Inhibitors
Authors: Hinchee Maud A. W. , Rost Th. L. 
Published: February 2014

AbstractLateral root development in cultured seedlings of Pisum sativum (cv. Alaska) was modified by the application of auxin transport inhibitors or antagonists. When applied either to replace the root tip or beneath the cotyledonary node, two auxin transport inhibitors, 2,3,5‐triiodobenzoic acid (TIBA) and 3,3a‐dihydro‐2‐(p‐methoxyphenyl)‐8H‐pyrazolo[5,1‐α]isoindol‐8‐one (DPX‐1840), increased cell division activity opposite the protoxylem poles. This resulted in the formation of masses of cells, which we are calling root primordial masses (RPMs), 2 to 3 days after treatment. RPMs differed from lateral root primordia in that they lacked apical organization. Some roots however developed both RPMs and lateral roots indicating that both structures were similar in terms of the timing and location of cell division in the pericycle and endodermis leading to their initiation. Removal of the auxin transport inhibitors allowed many of the RPMs to organize later into lateral root primordia and to emerge in clusters. When the auxin, indoleacetic acid (IAA) was added to the growth medium along with DPX‐1840, 3 ranks of RPMs now in the form of fasciated lateral roots emerged from the primary root. The auxin antagonist, p‐chlorophenoxy‐isobutyric acid (PCIB), also induced RPM formation. In contrast to DPX‐1840 treatment, the addition of IAA during PCIB treatment caused normal lateral root development.
Cyanobacterial Picoplankton from Lake Constance*
Authors: Ernst Anneliese , Sandmann G. , Postius Christine , Brass Susanne , Kenter U. , Böger P. 
Published: February 2014

AbstractFour types of unicellular cyanobacteria were classified by pigment composition and cell size. These originated from the picoplankton fraction of Lake Constance, Germany. β‐Carotene and zeaxanthin were found to be the main carotenoids of three Synechococcus isolates. In this group, coccoid forms with phycocyanin‐rich phycobilisomes also produce caloxanthin and nostoxanthin, which are xanthophylls with 3 and 4 hydroxy groups, respectively. In addition, these rare carotenoids are observed in rod‐forming Synechococcus isolates which contain phycoerythrin‐rich phycobilisomes, but they are very low or absent in the coccoid phycoerythrin‐rich isolates. Due to size and pigment content the coccoid forms are similar to Synechococcus leopoliensis (SAUG B 1402‐1, formerly Anacystis nidulans) and S. rubescens (SAUG B 3.81) while the rod‐forming isolates differ from S. elongatus (PCC 6716) in phycobilisome composition.The isolate BO 8402 was tentatively assigned to Synechocystis but differs in pigment composition from all strains described as yet. The green cultures exhibited a faint red glow due to an unusual high in vivo autofluorescence from phycocyanin. Neither were phycobilisomes found in a standard preparation nor was allophycocyanin present. The most abundant carotenoids are β‐carotene and caloxanthin, while zeaxanthin, with 12 % of all colored carotenoids, is low.All forms described in this paper lack complementary chromatic adaptation, indicating that the pigment composition is a reliable parameter to identify these freshwater isolates.
Changes in Sulfur Metabolism During Needle Development of Norway Spruce*
Authors: Schupp R. , Rennenberg H. 
Published: February 2014

AbstractIn a field‐study with approx. 150‐year‐old spruce trees, seasonal changes in thiol composition and content, sulfate content, and oxtractable activities of enzymes of sulfate reduction and assimilation were analyzed in needles and buds and were related to developmental processes during flushing. GSH was the predominant thiol in spruce needles throughout the year, with maximum contents of more than 400nmol g FW−1 during winter and minimum contents of less than 200 nmol g FW−1 during summer. Negative correlation of changes in GSI1 contents during winter and spring with air temperature showed a low correlation coefficient (r =– 0.55), suggesting minor significance of GSH in frost protection. Drastic changes in thiol contents during flushing suggested that GSH accumulated in the previous year's needles during winter supports the growing needles with reduced sulfur. Sulfate and other substrates for sulfate assimilation appeared to be available in buds and the new needles. An external supply with reduced sulfur may still be required because of insufficient activities of enzymes of sulfate reduction and assimilation, esp. ATP‐sulfurylase and APS‐sulfotransferase.
Secondary Carotenoids of Eremosphaera viridis De Bary (Chlorophyceae) Under Nitrogen Deficiency*
Authors: Vecktel B. , Kallmann U. , Ruppel H. G. 
Published: February 2014

AbstractUnder nitrogen deficiency the unicellular chlorococcalean green alga, Eremosphaera viridis De Bary, was able to synthesize secondary carotenoids (SC). Nine SC were identified as six astaxanthin esters, echinenone, canthaxanthin and a lutein ester, previously not described in green algae under nitrogen deficiency. These SC, jS‐carotene and the main part of lutein were located in lipid bodies outside the chloroplasts in the cytosol. The synthesis of SC could be inhibited by the herbicides norflurazon and nicotine. This result supported the idea that SC in cells ot Eremosphaera viridis were synthesized de novo rather than derived from primary carotenoids.
Confocal pH Topography in Plant Cells — Acidic Layers in the Peripheral Cytoplasm and the Apoplast
Authors: Roos W. 
Published: February 2014

AbstractThe distribution of intracellular pH was studied in cultured cells of Gossypium hirsutum by con‐focal pH topography using the fluorescent probe car‐boxy SNARF1 and a ratio imaging procedure. The resulting pH maps can visualize pH differences with an accuracy of 0.1 unit in the investigated range between 7.5 and 5.6. They reveal the following characteristic features of the Gossypium cells:– the pH of the cytoplasmic core regions ranges from near 7.4 in younger to near 6.0 in older cells;– vacuoles show the expected acidity with pH < 5.6;– the cell wall/apoplastic region is acidic with a pH near 5.6 or below, especially in young, growing cells;– interestingly, acidic areas appear also at the periphery of the cytoplasm, i.e. beneath the plasma membrane. They remain stable in the presence of 5/μmol/I of the protonophore CCCP.Acidic layers of peripheral cytoplasm were also detected in protoplasts of Penicillium cyclopium, i.e. eukaryotic cells of simpler structure, which served as a reference object. This ronfirms earlier findings obtained with classical fluorescence microscopy and another fluoroprobe (fluorescein diacetate). Though additional experimental support is needed, low pH regions at the cytoplasm/plasma membrane interface should be considered a real contribution to the pH control of plant and fungal cells, facilitating e.g. the maintenance of cytosolic pH in acidic environments.
Selective Reconstitution of the Tonoplast H+‐ATPase of the Crassulacean‐Acid Metabolism Plant Kalanchoë daigremontiana
Authors: Behre Barbara , Ratajczak R. , Lüttge U. 
Published: February 2014

SummaryIA detergent removal technique was used to reconstitute solubilized tonoplast proteins of mesophyll cells of the CAM plant Kalanchoë daigremontiana into phosphatidylcholine liposomes. The proteoliposomes were able to hydrolyse ATP and to pump protons across the vesicle membrane. Both activities were inhibited by nitrate, an inhibitor of V‐type ATPases. Freeze‐fracture micrographs confirmed the incorporation of membrane proteins into liposomes. Increase of specific ATP‐hydrolysis activity compared to solubilized tonoplast proteins and SDS‐PAGE analysis of reconstituted proteins in comparison with the polypeptide pattern of the purified tonoplast H+‐ATPase from the same plant source indicated a highly selective reconstitution of the tonoplast H+‐ATPase.
Travelling Pattern of Acidity in the Epidermis of Tulip Leaves
Authors: Hejnowicz Z. 
Published: February 2014

AbstractMany growing leaves of tulips show subtle undulations of their surface, oriented mostly transversely to the leaf axis. The undulations move acropetally with respect to cells. The epidermal peels from the leaves with the undulations placed on agar plates containing a pH indicator dye produce band patterns of more acid and less acid zones. Similar patterns also appear when the agar‐indicator is applied to the abraded leaf surface. This indicates that there is spatially variable H+ efflux from the epidermis into agar. No variation of the colour appears when the agar‐indicator is applied to the mesophyll surface formed by peeling off the epidermis, which indicates that the pH pattern is a feature of the epidermis only. The pattern of pH bands correlates closely with the pattern of undulation; more acid bands correspond to the convex zones of the surface. The movement of the undulations also indicates that the pH pattern moves, which means that in the epidermal apoplast the pH oscillates at a particular location.
Photoinhibition of Photosynthesis and its Recovery in Red Algae
Authors: Hanelt D. , Huppertz K. , Nultsch W. 
Published: February 2014

AbstractIn different marine red algae (Chondrus crispus, Delesseria sanguinea, Membranoptera alata, Phycodrys rubens, Phyllophora truncata, Polyneura hilliae) photoinhibition of photosynthesis has been investigated by means of both fluorescence and oxygen measurements. Measurements of absolute oxygen production show that photoinhibition causes a decline in the initial slope and in the rate of bending of the fluence rate‐response curve (i.e. the photosynthetic efficiency at non‐saturating fluence rates), as well as a decline in the photosynthetic capacity (Pm) at saturating fluence rates. Fluorescence data (Fv/Fm) were consistent with the results of oxygen measurements. Under excessive light photoinhibition protects photosynthesis against photo‐damage in red algae. However, an increase in the initial fluorescence (Fo) after photoinhibitory treatment indicates that it could not prevent photodamage entirely.Action spectra of photoinhibition demonstrate that the main photoinhibition site in Polyneura hiliae is PS II, because far red light absorbed by PS I was ineffective. The strong increase of Fo in the blue wavelength range and the slight and partial recovery in weak blue light indicate that blue light especially causes photodamage.Recovery of photosynthesis requires dim white light conditions. Experiments with monochromatic light also show a wavelength dependence of recovery. Moreover, the recovery of photosynthesis after a photoinhibitory treatment is strongly temperature dependent, indicating participation of enzymatic processes. The comparison of fluorescence and oxygen measurement of the recovery shows different results in some species. The rate of oxygen production in red control light increased immediately after photoinhibited algae were exposed to weak light conditions. Surprisingly, the ratio of variable to maximum fluorescence (Fv/Fm) of Phyllophora truncata and the maximum fluorescence (Fm) of Polyneura hilliae show first a delay of the recovery under weak light conditions. Thus, in recovery experiments fluorescence and oxygen data are not quite consistent.
Experimental and Modelling Studies of Competition for Light in Roadside Grasses
Authors: Beyschlag W. , Ryel R. J. , Ullmann I. 
Published: February 2014

SummaryEquiproportional mixtures and monocultures of two roadside grass species (Elymus repens (L.) Gould and Puccinellia distans (L.) Pari.) were grown in experimental field plots under non‐limiting water and nutrient conditions. During the course of the season, E. repens increasingly overgrew and shaded plants of P. distans which eventually died. A multispecies canopy photosynthesis model was parameterized using measurements of structural and physiological characteristics from three different stages of canopy development. Results of simulations clearly revealed that canopy photosynthesis of P. distans was highly dependent on the degree of light competition caused by E. repens. Since P. distans has recently invaded stands of roadside vegetation throughout Central Europe where it has replaced the native and highly competitive E. repens, it is hypothesized that this success is due to disturbance factors that keep E. repens from growing tall and shading P. distans.
In Vitro Ovary Culture of some Apogon Garden Irises (Iris pseudacorus L., I. setosa Pall., I. versicolor L.)
Authors: Laublin Geneviève , Cappadocia M. 
Published: February 2014

AbstractVarious organs of immature inflorescences from 32 selected genotypes of Iris versicolor, 6 of I. pseudacorus and 7 of I. setosa were cultured in vitro on two induction media supplemented with 45 μM 2, 4‐D or 4.5 μM each of 2, 4‐D and kinetin. Among the explants tested, peduncle sections showed a very limited response, and only ovary sections cultured under low light intensity consistently produced calluses and/or meristematic nodules on both media. This occurred in all genotypes of I. pseudacorus, whereas only a fraction of the genotypes belonging to the other species responded at the induction phase. Responding explants with callus and/or meristematic nodules were cut into halves and transferred onto a regeneration medium containing 22 μM benzyladenine, which induced shoot formation. Once again, large differences in response were noted among genotypes of each species. Those belonging to I. pseudacorus all gave a positive response producing vigorous shoots. Cytological analyses performed on 62 regenerated plants did not reveal changes in chromosome number.