摘要:

AbstractThe ATP‐ and pyrophosphate‐dependent proton pumps from tonoplast‐enriched vesicles prepared fromRubus hispiduscell cultures were solubilized in the presence of polyoxyethylene(9,10)p‐t‐octylphenol (Triton X‐100) and reconstituted into liposomes of soybean phospholipids, using Bio‐Beads SM‐2 to remove the detergent. The specific activity of the two pumps was greatly increased by the solubilization‐reconstitution procedure. Identical characteristics were found for pyrophosphate‐dependent proton transport in native and reconstituted vesicles. On the other hand, the ATP‐dependent proton transport of the reconstituted vesicles was no lon

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn search of a simple method for testing the very early events of ozone damage to susceptible plants as well as complete destruction after threshold‐exceeding treatments an over‐all measurement of cell ingredients by their optical density in the UVB and UVC range was investigated. The cell particles were liberated after membrane permeabilization or after cell bursting. Uncontrolled results could be excluded. Furthermore, the results of the developed spectrophotometrical test could be, in the case of tissue samples (leaf discs), very well reproduced with an osmometrical measurement. The latter was less sensitive and not suitable for cellular samples because the protoplasts must be dissolved in a nearly isotonic medium which caused too large a background for this method but not for the UVS test. Contrary to the osmometric measurement, the photometric one cannot be used for determining the absolute amount of cell ingredients but only for relative measurement between samples in a given range of concentrations. Oxidative changes of the liberated ingredients do not influence their detection, which was demonstrated with ascorbate. The developed leaching test was also useful for determining the membrane damage caused by the detergent Triton X‐100, although this was known to have UV absorbance by itself. It was noted that the far UV maximum is not only caused by absorbance and scattering is discussed as an additional explan

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA strong age dependency together with alterations in the cellular distribution of CX 26 immunorelated protein(s) was found for differently developed leaves ofVicia fabaL. With increasing age, an immunoreactive 40 kD band was observed in the soluble and microsomal fraction. In the cell wall protein preparation of young and fully differentiated leaves the 40 kD band was the minor constituent. A 33 kD polypeptide was dominantly localized in the microsomal fractions of all developmental stages and in SDS‐extracts of total cell proteins of young leaves. A 21 kD protein together with a 16 kD polypeptide was associated with the cell wall fraction. The 21 kD protein, assumed to represent a plasmodesmatal constituent, was reduced with age. In SDS extracts, prepared from the different developmental stages of the leaves and of mesophyll protoplasts, the age‐dependent appearance of the several immunostained bands was most obvious. A correlation of the 16, 33, and 40 kD bands to a turnover of the 21 kD protein is suggested. The reduced amount of the 21 kD protein with increasing age may be contemplated as an indication for a relative decrease of symplastic connections between cells of maturing leaves. This is in agreement with the results obtained by immunofluorescence studies using guard cell protoplasts. Here, observations pointed also to a reduction and final loss of CX 26‐related protein at the protoplast sur

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe electron‐opaque granules localized in vacuoles ofPaxillus involutushyphae associated withPinus sylvestrismycorrhizae, collected from heavily polluted sites were analysed by electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS) connected with the electron microscope (TEM 902, Zeiss). On the basis of the elemental composition two kinds of granules were distinguished. The first, similar in appearance to polyphosphate granules, described already for several fungi, was characterized by high contents of phosphorus accompanied by sulphur, calcium and often aluminium. More common, however, was the second sort of granules containing more nitrogen, sulphur and cadmium, while the amount of phosphorus was much lower. The data reveal accumulation of cadmium inside fungal vacuoles and suggest the possibility of detoxification of heavy metal by the symbiotic fungu

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractHypocotyl protoplasts fromHelianthus annuusL. were electrically stimulated using different parameters and subsequently cultivated in agarose droplets with weekly changes of the liquid media. Macroscopic visible calli (0.1‐0.3 mm) were transferred onto solid media supplemented with different concentrations of NAA, BAP, and GA3. Colonies reaching a size of about 3 mm were isolated and further cultivated under the same conditions. Several calli originating from electrically stimulated protoplasts and especially those cultured on relative high auxin concentrations, generated somatic embryos which were characterized by a green globular shoot tip and a developing root. Later on differentiation of the shoot tip occurred on kinetin‐containing MS medium leading to plantlets with stunted shoot axis. No somatic embryos were initiated in control experiments with non‐stimulated protop

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRoot chilling has been shown to inhibit shoot photosynthesis yet the mechanism for such an action is not clearly understood. A study was designed to elucidate the mechanism by which root cooling may affect net photosynthesis. Roots ofArtemisia tridentataseedlings were cooled from 20°C to 5°C while their shoot temperature remained at 20°C. This was conducted at two light levels (700 and 1300 μmol m−2s−1). The time course of shoot net photosynthesis (A), stomatal conductance to water vapor (gs), intercellular CO2concentration (Ci) and root respiration (Rs) were determined on a whole‐plant basis. Root cooling caused a 25% reduction in A at high PPFD, which was preceded by more than 50% reduction of gsand about 10% reduction in Ci. A versus Cicurves for single branches showed no difference between cold and warm soil temperatures, although stomatal conductance was lower for the lower soil temperature. This suggests that a stomatal limitation may have been involved in the inhibition of A. Furthermore, a concomitant decrease of as much as 23% in leaf relative water content (RWC) indicated that root cooling affected stomatal closure due to decreased water supply to the foliage. At lower PPFD, root cooling did not cause a decrease in A of the whole plant despite a moderate drop in gs, Ciand RWC. Cold soil also led to a substantial and rapid reduction in root respiration rate (Rs) regardless of the li

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study the influence of nitrogen nutrition on the patterns of carbon distribution was investigated withUrtica dioica. The nettles were grown in sand culture at 3 levels of NO−3, namely 3 (low), 15 (medium) and 22 (high) mM. These levels encompassed a range within which nitrogen did not affect total biomass production. The ratio of root: shoot biomass of the low nitrogen plants was, however, significantly higher than that of the nettles grown at medium and high N supply. Carbon allocation from one leaf of each pair of leaves was examined after a14CO2‐pulse and a subsequent14C distribution period of one night. Only the youngest two leaf pairs did not export assimilates. Carbon (14C) export to the shoot apex and to the roots, as measured at the individual nodes responded to the nitrogen status: At medium and high nitrogen supply the 3rd, 4th and 5th leaf pairs exported to the shoot apex, while lower leaves exported to the root. At low nitrogen supply only the 3rd leaf exported towards the shoot apex. The results illustrate the plastic response of carbon distribution patterns to the nitrogen supply, even when net photosynthesis, carbon export from the source leaves and biomass production were not affected by the nitrogen supply to the pl

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe natural cytokinin import from the root into the shoot ofUrtica dioicaplants was enhanced by supplying zeatin riboside (ZR) solutions of various concentrations to a portion less than 10 % of the root system after removal of their tips. After 6 h ZR pretreatment of the plants,14CO2was supplied for 3 h to a mature (source) leaf or to an expanding leaf and the14C‐distribution in the whole plant was determined after a subsequent dark period of 14 h.ZR substantially increased14C fixation by the expanding leaves and also enhanced export of carbon and transport to the shoot apex. The effect of the hormone treatment was, however, more pronounced when the14CO2was supplied to a mature leaf. In the control plants these leaves exported carbon only to the roots: When the amount of the natural daily ZR input from the roots to the shoot was enhanced by 20%, the bulk of the14C exported from a mature leaf moved to the shoot apex and only a minor portion of14C was still detected in the root fraction. A several‐fold increase of the natural daily ZR input into the shoot resulted in a flow of14C only to the growing parts of the shoot. The results suggest control of the sink strength of the shoot apex by ZR inUrtica dio

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00746.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA comparison of developmental features and physiological responses between the modified stomata (MS) of the floral nectary and the stomata of leaves ofVicia fabaL. has revealed several significant differences. In mature tissues, the frequency per unit area of MS is three times that of foliar stomata, and when only the distal quarter of nectary projections is considered, it is twelve fold higher. The walls of guard cells (GCs) of MS near the pore were four to five times thinner than those of their foliar counterparts. Average pore widths of the nectary MS remained constant throughout the day and night, contrary to those of leaves; maximal foliar apertures were similar to average pore widths of MS of nectaries. Experiments with plasmolytica demonstrated a higher osmotic potential in nectary MS, and that sister GCs of the nectary only occasionally closed their pores by movements, even when they were plasmolysed, whereas GCs of leaves were found to be plasmolysed only after their pores had shut. Abscisic acid (ABA) was always detected naturally in floral nectar. The results of experiments involving K+‐localization and the secretion of large quantities of ABA in nectar suggested that GCs of the MS lack operational systems involving K+‐influx and ABA‐receptor sites. All information gained is consistent with the earlier conclusion that the MS do not have a regulatory role in nectar secretion by flowers ofV.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00747.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe ozone‐sensitive tobacco varietyBel W3was compared with the tolerant cv.Bel Busing amphidiploid and amphihaploid genotypes of both. In search of the first genotypical differences, their reaction to acute ozone treatments was investigated with systems of decreasing degree of complexity: whole plants, grown under field, greenhouse and sterile conditions, excised tissues, calli, CCP, MCP and subcellular reactions. It was common to all systems that a fumigation, which clearly exceeds the threshold of the most tolerant material, led to equal reactions in all genotypes in respect of visible injury and membrane leaching. With whole plants and leaf discs growing conditions were found to influence the ozone threshold more than the genotype. Because the most resistant field‐grown plants vary widely in their reaction, only sterile or greenhouse grown genotypes were compared. With the exception of whole sterile plants (no genotypical threshold differences), amphihaploids were more susceptible to ozone than their respective amphidiploids as to threshold and sensitivity spectra in all systems investigated. Higher ozone thresholds were detected forBel Bin all systems with one exception: MCP exhibited a lower threshold but also a lower degree of damage in the first buffer range of the sensitivity spectrum than those ofBel W3. Post‐fumigation starch accumulation in mesophyll chloroplasts was the most prominent subcellular ozone rea

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1993.tb00748.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY