摘要:

AbstractThe calcium ionophore A23187 was used to separate the processes of infection and nodule development from nitrogen fixation in soybeans. Seedlings ofGlycine max(L.) Merr. cv. Williams were grown in solution cultures containing three concentrations of Ca2+(0.1, 0.5 or 1.0 mM) with or without 0.5 μMionophore A23187. Three weeks after inoculation withRhizobium japonicum, strain B1. plants were harvested. Low Ca2+(0.1 mM) significantly reduced nodule number and weight, acetylene reduction, fresh weight of roots and shoots and increased lengths of 2nd and 3rd internodes. There were no significant differences between 0.5 and 1.0 mMCa2in their influence on any parameters measured, except for Ca2+concentration in the tissue. The ionophore A23187 significantly reduced nodule number and weight, and increased internode lengths, but it had no effect on acetylene reduction or fresh weight of roots and tops. The ionophore did not affect the Ca2+concentration of roots, tops or nodules. Therefore, nitrogen fixation rate is partially independent of number and weight of nodules. The single most important result of this study is that the ionophore A23187 affected critical steps in the infection process or nodule development without influencing subsequent nitrogen fixation

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04876.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn order to find naturally occurring white‐rot fungi which preferentially degrade lignin. 25 different species of such fungi were cultivated on pine wood blocks and on kraft lignin agar plates with and without cellulose. Due to differences in phenol oxidase reactions on the kraft lignin agar plates, the 25 fungi could be divided into two groups, 1 and 2, which also differed in other properties. The three Group I fungiSporotrichum pulverulentum, Phanerochaetesp. L1 andPolyporus dichrousproduced high levels of endo‐l,4‐β‐glucanase and cellobiose:quinone oxidoreductase in shaking cellulose flasks and a low level of phenol oxidase in standing wood meal flasks, The four fungiMerulius tremellosus, Phlebia radiata, Pycuoporus cinnabarinusandPleurotus ostreatusfrom Group 2, on the other hand, produced low levels of endo‐1,4‐β‐glucanase and cellobiose:.quinone oxidoreductase in the cellulose. flasks and a high level of phenol oxidase in the wood meal flasks.Analyses of pine wood blocks degraded by the above‐mentioned fungi in the presence of either malt extract, asparagine or NH4H2PO4revealed that malt extract gave good lignin degradation. In the presence of this nutrient source.P. cinnabarinus, at 3.4% weight loss, even degraded 12.5% lignin without loss of cellulose or mannan. No common degradation pattern was, however, obtained using mall extract, asparagine or NH4H2PO4, It is suggested that while‐rot fungi, which preferentially degrade lignin, may be found among Group 2 fungi producing large amounts

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04877.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractGalactose enhances the production of ethylene gas, and ethylene gas inhibits the movement of IAA in plant tissues. If galactose enhances ethylene production and ethylene inhibits auxin movement, then galactose should inhibit auxin movement. The above hypothesis was examined by observing the effects ofd‐galactose,d‐inannose,d‐arabinose,d‐glucose, anddxylose on the uptake, presumed decarboxylation, efflux, velocity and metabolism of labeled indole‐3‐aectic acid in hypocotyl segments ofPhaseolus vulgarisL. cv. Pinto. Galactose inhibited, arabinose and glucose enhanced, and mannose and xylose had no effect on partitioning of auxin between tissue and receptor. The reduction of auxin efflux by galactose was related to an increased presumed decarboxylation, reduced uptake and slower velocity of applied auxin. The relationship between galactose‐induced growth effects, ethylene production, and auxin migration

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04878.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractVegetative plants ofSinapis albaL. grown in short days were induced to flower by expsoure to one or continuous long days. In both inductive conditions, the first flowers were initiated about 60 h after the start of the treatment. Soluble protein extracts were prepared from apical buds and just‐expanded leaves of both vegetative and induced plants. Rabbit antisera were prepared using extracts from vegetative and reproductive buds. Immunodiffusion tests were performed. Analysis of the precipitin bands indicated that: (1) one antigenic protein was present in the vegetative buds and disappeared from the buds of induced plants between 96 and 240 h after the start of the inductive treatment; (2) the concentration of a another antigenic protein increased in buds of induced plants 30 h after the start of the inductive treatment; (3) the concentration of a third antigenic proteín increased in buds of induced plants at 96

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04879.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractVelocity of IAA movement was determined by noting the time of arrival of an ether‐soluble auxin wave, at a fixed distance, after presentation of an auxin pulse to bean (Phaseolus vulgarisL. cv. Pinto) hypocotyl segments. The effects of IAA adsorption on wave symmetry were reduced by monitoring the arrival of ether‐soluble auxin molecules. Velocity of auxin movement, as estimated by wave arrival, was slower than velocity estimated by the intercept method in controls and in both iodoacetate (IOAA) and 2,3,5‐triiodobenzoic acid (TIBA) treated tissue. Velocity of wave migration was reduced by both treatments but intercept velocity was reduced only by TIBA treatment. Velocity of IAA migration was faster in segments (independent of method of measurement) than from segments into agar by a factor of 4 to 8. The rate limiting step of auxin migration in the traditional agar‐plant sandwich is the partitioning of IAA between the tissue and agar. It was suggested that arrival curves for pulsed auxin migration are analogous to elution profiles of chromatographic columns and that at least two populations of mobile molecules with different velocities exist. It was also suggested that the two velocities represent migration of auxin on two different pathways: the faster velocity representing auxin movement of water films which coast highly crosslinked polymers in the segment and the slower component representing a population which moves primarily within the matrices of crosslinked polymers. Velocity of both populations may be a function of tissue hydration and charge interactions of mobile molecules and matrix p

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04880.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe seeds ofCrithmmm maritimumL. were germinated floating on various concentrations of sea water up to 50% at constant temperatures of 5, 10, 15, 20, and 25°C and at alternating temperatures of 5 and 15°C. 5 and 25°C. and 15 and 25°C. Significantly higher germination was obtained at alternating than at constant temperature. When two constant temperatures at which no germination occurred were alternated, good germination was obtained. There was reduced germination and increase in time of first germination as sea water concentration increased, in the absence of sea water, high temperature caused not only severe inhibition of germination but also permanent injury to the seeds. The results help to explain the germination behaviour of the species in nat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04881.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe characteristics of cadmium accumulation by the marine red algaPorphyra umbilicalisL. in culture are reported. The time course of uptake under various light conditions shows that cadmium is concentrated as the result of an on‐going anabolic process and not as a consequence of a pH gradient as provided by photo‐synthesis. The effect of cycloheximide is in agreement withde novoprotein‐synthesis being a prerequisite For cadmium accumulation. Autoradiography suggests a specific intracellular location for bound cadmium—apparently the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04882.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractMeasurements were made of the amount of liquid water present in the epidermal cells of onion at various degrees of dehydration caused by slow extracellular freezing and by desiccation. This was achieved by using a pulsed NMR spectrometer during freezing stress and by weighing the epidermal pieces during desiccation. Measurements were made on the extent of cell survival by direct microscopic observation (plasmolysis and protoplasmic streaming).Onion epidermal cells (Allium cepaL. cv. Downing Yellow Globe) were found to survive freezing temperatures as low as –20°C and an equivalent desiccation stress. This equivalence opposes the reports by others onHordeum vulgareand onSolanumsp. of greater injury by freezing than by an equivalent dehydration due to desiccation. The discrepancy ‐has been explained in terms of the limitations of the conductivity method used by those authors to evaluate the injury.The freezing and desiccation curves correspond to the equation:Lt=L0Δtm/t+LuwhereLtandL0are the amounts of liquid water at temperaturetand O°C respectively. Δtmis the freezing point depression of the cell sap andLuis the amount of liquid water which does not freeze.These results demonstrate that the dehydration of onion cells during both freezing and desiccation duplicates the dehydration of ordinary aqueous solutions. This was equally true for living and dead cells, and suggests that the negative turgor invoked by others is not significantly involved in the dehydration of livingAllium cepaepidermis cells. An explanation is proposed for these contradictory

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04883.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe influence of different growth irradiance conditions on plant development and foliar features were assessed in a shade‐adapted fern variety,Pteris creticavar.ouvrardii. A comparison of frond morphology, anatomy, chloroplast infrastructure and chlorophyll content of plants cultivated in both greenhouse and in controlled growth chambers under moderate light, low light (control) and extreme shade revealed pronounced phenotypic modifications. Moderate light induced decreased frond surfaces, thicker leaves, lower chlorophyll content per surface unit, and a markedly reduced density of intraplastidial membranes. In contrast, morphological responses to extreme shade included the formation of larger, thinner fronds, increased chlorophyll content; and a higher membrane density in chrloplasts. A dorsi‐ventral distribution of starch‐gorged chlroplasts (lower mesophyll cell layers) and essentially starch‐free chloroplasts (upper cell layer) characterizes low‐light and moderate light fronds, while homogenous starch‐free chloroplasts are present in all cell layers of extreme shade fronds. The light‐induced modifications are discussed as adapt

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04884.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of chilling was studied in leaf discs from the chilling‐sensitiveCucumis sativusL. by measurement of the electrolyte leakage from the discs, by oxygen uptake and by uncoupling of respiration with 2,4 dinitrophenol. Short periods of chilling are characterized by minor significant increases of electrolyte permeability, of respiration and of preserved ability to be uncoupled by 2,4‐dinilrophenol. A longer period of chilling resulted in a strongly increased electrolyte permeability, in reduced oxygen uptake and in disappearance of uncoupling by 2,4 dinitrophenol. In general the induced changes in permeability and respiration were reversible within 4 days of chilling, if the discs were placed at 25°C after chil

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1977.tb04885.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY