摘要:

Books reviewed in this article:TERRESTRIAL PLANT ECOLOGYBy M. G. BARBOUR, J. H. BURK&W. D. PITTSUNDERSTANDING CELL STRUCTUREBy MARTINW. STEERTISSUE CULTURE METHODS FOR PLANT PATHOLOGISTS. Edited by D. S. INRAMAND J. P. HELGESONOPPORTUNITIES FOR INCREASING CROP YIELDS. Edited by R. G. HURD, P. V. BISCOE&C. DENNISTHE BIOLOGY OF DESMIDS. By A. J. BROOK

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02110.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Water permeability of cuticular membranes (CM) from the inner bulb scales ofAllium cepahas been investigated. CM have a thickness ranging from 0.6 to 1.3 μm. They are composed of a thin (120–200 nm) lamellated cuticle proper and a thicker (300–900 nm) cuticular layer. Permeability coefficients for diffusion of water across these thin membranes are very low (4 × lO−10ms−10). There was no difference in permeability of CM from successive scales of the same onion. Extraction of soluble cuticular lipids (SCL) with chloroform increased permeability by a factor of 1350 to 2050. Preliminary data indicate that only 1 μg cm−10of SCL are removed by this treatment, hydrocarbons being the main (75%) consistuent. Permeability coefficients of cuticular transpiration were little affected by relative humidity, showing that transport is limited by a hydrophobic barrier that lacks dipoles. However, following extraction, permeability of the membranes depended strongly on humidity due to the presence of polar functional groups in the polymer matrix. Soluble cuticular lipids undergo a phase transition around 47°C. Temperatures higher than that irreversibly increased water

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02111.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Mitochondria were found to be aligned along the upper periclinal walls of aleurone and endosperm cells in developing rice caryopses. The significance of this distribution is discussed in relation to previous studies of solute transport in rice.

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02112.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.An analysis of nutrient uptake by batch cultures of sugar‐cane cells was performed to gain information about the ionic balance during uptake of charged metabolites. Whereas younger cultures (up to 1 week old) have to compensate excess cation influx with proton efflux, older cultures show balanced cation–anion uptake.Younger cells produce a small amount of carboxylic acids to furnish protons for charge compensation at the cytoplasmic membrane. Older cells synthesize organic acids more abundantly to generate protons necessary for the proton demand of nitrate and sulphate assimilation. Despite these assimilation reactions only a small percentage of carbon, which is taken up mainly as hexose, needs to be oxidized to carboxylic acids for that purpose. In contrast, younger cultures preferentially use the amino acids of the medium instead of assimilating nitrate. The use of amino acids as a nitrogen source does not require a significant part of metabolism for biochemical pH‐stability, whereas an efficient proton circulation on the cytoplasmic membrane seems to be of major importance.A balance study of the main metabolized elements, carbon, nitrogen and sulphur was performed to get a quantitative impression of the fate of these nutrients during growth of cell cul

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02113.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The glycerol and starch metabolism of synchronizedDunaliella parvacells as a function of the salinity of the medium has been investigated.The higher the salinity of the medium the higher is the rate of glycerol synthesis and the endogenous glycerol concentration, whereas starch content and salinity of the medium are inversely related. Upon transfer to a hyperosmotic NaCl‐medium cells respond by an immediate increase in glycerol synthesis and an inhibition of starch formation in the light. Under corresponding conditions in darkness, starch degradation is stimulated. In both light and darkness hyperosmotic shocks are followed by a rapid increase in the endogenous pool of inorganic phosphate (Pi). It is suggested that in the light the increase in the endogenous phosphate level inhibits the chloroplast ADPG‐pyrophosphorylase (E.G.2.7.7.27), and thereby starch synthesis, and promotes starch phosphorolysis. Photosynthetically produced triosephosphates and triosephosphates derived from starch degradation are converted to glycerol. Also, in the dark the increase in the Pi‐level stimulates phosphorolytic starch degradation and thereby synthesis of glycerol. Reasons for the salt stress induced increase in the endogenous Pi‐level are di

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02114.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The rise in phenylalanine ammonia‐lyase (PAL) activity following excision of potato tuber discs is antagonized by increasing partial pressures of CO2This inhibition is potentiated by depleting the atmospheric ethylene level. We suggest that the previously observed suppression of PAL appearance byin situincubation of excised discs in reassembled tubers may be related to an internal atmosphere relatively rich in CO2and of low ethylene content. The transition to an oscillatory time course of PAL activity that follows transfer of discs fromin situincubation to air appears to be accompanied by the development of enzyme activity becoming desensitized to repression by exogenous cinnamate. The concentration dependence of cinnamate uptake is not significantly altered byin situpre‐incubation of tuber di

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02115.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The uptake of triphenyltin chloride byEnteromorpha intestinalisandUlothrix pseudoflaccazoospores and vegetative tissue was examined under various conditions affecting the metabolic state of the chloroplast. A synthesis for [113Sn]‐triphenyltin chloride is presented. Results indicate that uptake of [113Sn]‐triphenyltin chloride by vegetative tissue (and probably zoospores) is a passive process. Differences in the uptake of [113Sn]‐triphenyltin chloride by zoospores of the two algae, in the dark and light, and by vegetative tissue of the two algae in the light, cannot be explained readily on the basis of surface area available for adsorption. Uptake studies suggest that differences in response to triphenyltin chloride exist between vegetative tissue and zoospores. Treatments which depress chloroplast membrane energization in vegetative tissue, e.g. lack of light, the presence of the uncoupler carbonyl cyanide m‐chlorophenyl hydrazone (CCP) or of DCMU prevent the exchange of triphenyltin chloride in pulse‐chase ex

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02116.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The heat pulse method for determining sap flux in large woody sterns was modified for easier field operation. It uses the measurement of the time elapsed between heat pulse release by a line heater radially inserted in the stem, and the occurrence of maximum temperature 15 mm downstream of the heater. This spacing between heater and thermometer is critical to the reliability of the measurement. Calculations using uncorrected theory provide estimates of the sap flux density in stems with both uniform and non‐uniform cross‐sectional distribution of conducting tissues which are about 55% of the actual sap flux density. This factor results from insufficient thermal homogeneity between tissues where sap flow occurs and tissues where sap flow has been interrupted.Sap flow in trunks of citrus trees was inferred from measurements of the cross‐sectional distribution of sap flux density. Variability of sap flux density is specific to each trunk and is time‐dependent and imposes multiple radial and angular measurements. The method was checked in a citrus trunk ramified into three branches. Instantaneous determinations of the flow in the trunk and in the branches differed by less than 5.7%. The daily values agreed with

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02117.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The influence of a slow stress and recovery cycle on the pattern of leaf expansion in four diverse sunflower cultivars (Helianthus annuusL. cvs. Hysun 31, Havasupai, Hopi and Seneca) was studied in a glasshouse. Stress had no significant effect on the time of flower bud emergence and anthesis, or on final leaf number, but delayed the appearance of leaves at high insertions in all cultivars except Hysun 31.Leaf expansion was markedly reduced as the predawn leaf water potential decreased from −0.35 to −0.60 MPa, and the predawn turgor pressure decreased from 0.3 to 0.2 MPa, and expansion ceased at a predawn leaf water potential of about −1.0 MPa, i.e. when the predawn turgor pressure reached zero.The leaves most reduced in final size when water was withheld were those at the insertions which grew the most rapidly in unstressed plants. The maximum reduction in final leaf size of 25–35% was similar in all cultivars and was due to retardation of the rate of leaf expansion: the duration of leaf expansion was actually increased by stress. However, leaves that were initiated during stress, but emerged after rewatering, had final leaf areas at least equal to those in the unstressed plants: in the cultivar Seneca, the final size of leaves of high insertion was significantly greater in stressed than unstressed plants, whereas in the three other cultivars the final leaf sizes were similar in both treatments. All four cultivars examined adjusted osmotically to the same degree, but leaf water potentials in one, Seneca, increased more rapidly after rewatering than in the other three, and this may have contributed to the greater relative leaf size in the leaves of high insertion in this c

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1981.tb02118.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY