摘要:

Books reviewed in this article:NICOTIANA: PROCEDURES FOR EXPERIMENTAL USE. Edited by R. D. DurbinVIROIDS AND VIROID DISEASES. By T. O. Diener

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1980.tb00099.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.Potential sources of reductant for the pathway of nitrate assimilation in non‐photosynthetic tissue are considered in terms of the intracellular distribution of the enzymes involved (relative to those of nitrate assimilation), their maximum catalytic capacity, the availability of their respective substrates, and the form in which the reductant is produced. According to these criteria, the principal sources appear to be the reactions catalysed by NAD‐glyceraldehyde‐3‐phosphate dehydrogenase, glucose‐6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase, NAD‐malate dehydrogenase and NADP‐malic enzyme. Mitochondrial metabolism may also make a limited contribution, although the evidence is inconclusive. The capacity to generate reductant by carbohydrate oxidation within the proplastids appears insufficient to meet the demand, and an influx of reducing power from the cytoplasm in the form of dihydroxy acetone phosphate may be necessary to support nitrite reduction and the glutamate synthase reaction

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580887

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.We measured phytochrome content by radioimmunoassay in green, light‐grown oats (Avena sativaL., cv. Garry) grown under several light regimes. Phytochrome content increased linearly to six times the light‐grown level during a 24‐h dark incubation and to fifty times the light‐grown level after 48 h darkness. Phytochrome content, in response to a cycle of 12‐h light, 12‐h dark photoperiods, increased to three times the light‐grown level in darkness and returned to the light‐grown level during the subsequent light period. Plants given far‐red light immediately prior to a 12‐h dark period contained about four‐fold more phytochrome than light‐grown oats, compared with a three‐fold increase in plants treated identically except given no far‐red light. We also attempted, unsuccessfully, to eliminate a general nonspecific interference by crude plant extract

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580894

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.It is proposed that the growing plant can be divided into three compartments with reference to carbon: soluble, storage and structural. Experiments carried out at 10, 15, 20 and 30°C in the light followed changes in size of these compartments in barley plants 10–24 days old. The redistribution ofI4C photo‐assimilated by 10 day old plants was monitored simultaneously. The soluble and storage compartments are a higher percentage of plant weight at lower temperatures, and are turned over rapidly at all temperatures; they form the source of respired14C. About 30% of the14C fixed enters structural material; in the first 24 h after labelling, for each unit of14C entering the structural compartment, between 0–9 (at 15°C) and 3.2 (at 30°C) units of14C are lost by respiration. At 15°C in the dark, respiratory loss of14C is initially from soluble and storage compartments; thereafter respiration ofI4C occurs at the expense of structural

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580903

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.Paraquat treatment of susceptibleLolium perenneseedlings (cultivar Kent Indigenous) rapidly inhibited CO2uptake and after 1 h chloroplasts exhibited abnormal fusions of the thylakoid membranes. Further ultrastructural changes occurred within the chloroplasts until 8 h after treatment, when cytoplasmic damage also became evident. The localization of primary damage within the chloroplast differs from previous reports of paraquat toxicity in other species. Paraquat treatment of tolerantL. perenneseedlings (line PRP IX) resulted in little change in CO2uptake and ultrastructural effects were generally confined to the gradual development of deposits in the chloroplast stroma. These observations are discussed in relation to the mechanism of action of the herbicide and the proposed mechanism of paraquat tolerance inL. perenne.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580909

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.The effect of sub‐lethal concentrations of copper upon tolerant and non‐tolerant strains ofChlorella vulgariswas investigated. Copper concentrations of 0.2 and 0.4 mg dm−3increased the lag phase of both strains, the effect being greater in the non‐tolerant strain. No difference was observed in the toxicity of copper to the photosynthetic rates of the isolated chloroplasts of either strain. However, significant differences were shown at the whole cell level.Lower copper uptake was shown by the tolerant cells. In both strains initial uptake of copper was followed by a phase of desorption before cell division occurred. In cultures of both strains the concentration of ionic copper was decreased by complexation with extracellular organic material. Over a 14 day growth period more organic material was produced by the tolerant cells. The organic material produced by the tolerant cell formed organo‐copper complexes which had a higher conditional stability constant.It is proposed that the cell wall acts as a barrier to copper in the tolerant cells and prevents copper from affecting cell metabolism. Organo‐copper complexation occurs at this barrier and this complex is then released into

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580913

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.Measurement of the electrical field along soybean hypocotyls shows the development of a positive electrical potential in the lower side approximately 1 min after horizontal placement. The time is as fast or faster than the geotropic presentation time of soybean seedlings. The maximum positive electrical field potential is produced in a zone 1–2 cm below the hook, which is the region showing the geotropic curvatur

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580916

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.Diurnal measurements of total water potential and stomatal opening were made at six sites. Pressure‐volume curves were established on parallel leaf samples. In eastern Austria, the species investigated wereCornus mas L., Cornus sanguinea L., Crateagus monogyna Jacq., Sorbus aria(L.) Crantz andViburnum lantanaL. in southern FranceCrateagus monogyna, and in southern TurkeyCrateagus monogyna and Olea europaeaL. Osmotic adjustment, defined as a change in osmotic potential larger than the passive change resulting from the loss of cell water, was relatively small from day to day or week to week in mature, non‐senescing leaves.Cornus sanguineawas an exception. A recently suggested method for the demonstration of diurnal active osmotic adjustment seems not to be reliable without further independent corroboration. Changes in the leaf water potential threshold for stomatal closure were either insignificant when the pressure‐volume characteristics of the plant material were stable, or significant when shifts in such parameters as the turgor loss point occurred (Cornus sangu

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580919

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.Leaf sections (1 × 1 cm) fromChenopodium rubrumL. were floated on Murashige–Skoog medium at constant 20°C and 8800 Lux white fluorescent light. During a period of 4–6 days after inoculation the leaf tissue showed rapid growth and cell division in the mesophyll. Subsequently, after 4 days on a rotary shaker the leaf tissue completely disintegrated and released a great number of single cells into suspension. This procedure, which by‐passes the callus culture stage, is well‐suited to the rapid production of standardized cell suspension

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580923

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Abstract.It has been shown that atmospheric O2can either depress or stimulate the rate of apparent photosynthesis of white mustard depending on the environmental conditions: CO2concentration, light intensity and temperature. Stimulation by O2was observed only under high photon fluence rate and at high CO2concentrations. The critical CO2concentration below which O2was inhibiting and above which it was stimulating was dependent on the temperature of the assay: for plants grown at 12°C the critical CO2concentration was 13.35 mmol at 5° C and 21.92 mmol at 10° C. Stimulation by O2depended also on the growth temperature: for measurements at 26.31 mmol m−3CO2, O2was stimulating at temperatures less than 12°C for plants grown at 12°C and less than 19°C for plants grown at 27°C. The efficiency of the O2‐dependent stimulation of net photosynthesis was maximum at 9.21 mol m−3O2at 26.31 mmol m−3CO2.Oxygen‐stimulation of net photosynthesis was detected inNicotiana tabacumL. var Samsun,Lycopersicum esculentumL. andChenopodium albumL. At 5°C and under high photon fluence rate, O2increased the carboxylation capacity of the photosynthetic apparatus of mustard and decreased its affinity for CO2. The O2inhibition of the net CO2uptake observed at low CO2concentrations was the result of a decrease in the affinity for carbon dioxide. The nature of the mechanism which causes the stimulation of photosynth

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11580938

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY