摘要:

AbstractA generalized model of the higher plant body is proposed in order to assemble the discrete knowledge of the actions, and sites of biosynthesis, of phytohormones. In this model, we attempt to explain the differential sensitivities of different tissues. With this model most effects of plant hormones appear to be reasonable, and even expected. The model is based on a new anatomical and physiological classification of plant tissue. In higher plants the integration of an outer‐inner polarity and an upper‐lower polarity plays a major role in phytohormone behaviour.Plant tissues and organs which are derived from the cortex of paleophytes (the bud, the mesophyll of the leaf, the cortex of the stem, and the root cap) are classified as the outer pole of the plant. On the other hand, tissues and organs which are derived from the stele of paleophytes (the root, the stele of the shoot, and the vein of the leaf), are classified as the inner pole. It is suggested that tissue sensitivities to phytohormones are mainly determined by the outer‐inner polarity. Phytohormones which are synthesized from one pole act on the other, whereas they exert either much less or no effect, or an inverse effect on their own pole. This is shown for both promoters and inhibitors of the phytohormones for both cortical and stelar vegetative tissues of p

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01559.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractLeaf shapes and leaf orientation ofLactuca serriola serriolaandserriola integrifoliawere studied. Leaf shapes in L.serriola serrioladiffered greatly from those of L.serriola integrifolia, but leaf surface areas were similar. In exposed habitats, leaf orientation of cauline leaves of both forms was non‐random, with leaves almost vertical and tending to orient with their lamina normal to the east and west. In the shade, cauline leaves oriented randomly. An experiment demonstrated that the orientation of leaves did not change significantly once they were fully expanded. The leaf orientation in L.serriolaaffected the diurnal distribution of solar irradiance intercepted by a leaf. Peak solar radiation fluxes are incident on the rosette leaves at midday, but on the cauline leaves the peak solar radiation flux occurs early in the morning and again late in the afternoon. The significance of this unusual leaf orientation is discussed in relation to water loss and carbon gai

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01560.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effects of light and gibberellic acid (GA3) on growth and phenylalanine ammonia‐lyase (PAL) activity were studied in seedlings of lettuce (Lactuca sativaL.). Using anin vivoassay for PAL it was shown that wounding caused by excising hypocotyls results in an increase in PAL activity with time that can mask the effect of light on the activity of this enzyme. When hypocotyl sections were excised from light‐treated seedlings immediately prior to thein vivoassay of PAL, light was shown to cause a marked increase in PAL activity. Experiments with an inhibitor of PAL activity, α‐aminooxy‐β‐phenylpropionic acid (AOPP), confirmed that the volatile radioactive products measured in thein vivoassay resulted from the activity of PAL. Gibberellic acid suppresses the light‐induced increase in PAL activity and there is an inverse relationship between GA3‐induced growth and the activity of PAL. Over a wide range of GA3concentrations, the activity of PAL is also inversely correlated with growth rate along the length of the hypocotyl section; the upper halves of sections elongate more rapidly and have lower levels of PAL than the lower halves. Despite the strong correlation between growth and PAL activity, experiments with AOPP andt‐cinnamic acid show that it is unlikely that elongation is regulated directly by product

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01561.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbastractMeasurements of growth increments on the shaded and the irradiated sides of phototropically stimulated maize (Zea maysL.) coleoptiles, obtained over the entire fluence range of the first positive curvature, indicate that the curvature is induced by growth stimulation on the shaded side and compensating inhibition on the irradiated side (length increments on the coleoptile flanks were determined 100 min after 30 s phototropic induction with blue light). At high fluences of blue light, overall stimulation of growth takes place, but this tendency is largely eliminated when only the tip of the coleoptile is irradiated. Time courses for growth increments obtained for the maximum first positive response show that the growth stimulation on the shaded side and the growth inhibition on the irradiated side commence almost simultaneously 20‐30 min after the phototropic induction. The growth on the irradiated side almost ceases, but the growth rate on the shaded side is doubled, relative to the control rate. The onset of differential growth migrates basipetally from the tip at a velocity similar to that for polar auxin transport. The first positive phototropic response of the coleoptile is concluded to be the consequence of lateral redistribution of growth, which is not necessarily accompanied by changes in the net growth. The results are consonant with the Cholodny‐Went theory of tropisms, in which lateral redistribution of auxin is considered to be the cause of tropic respon

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01562.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractStem chlorenchymatous cells from well‐watered and water‐stressed plants ofCissus quadrangularisL. were examined to evaluate the effect of drying on cell structure and metabolism. At a stem relative water content as low as 52‐58%, cellular integrity was maintained, but some qualitative and quantitative alterations occurred. Chlorophyll coment was higher in stressed plants, and the intact photosynthetic apparatus exhibited an increased degree of thylakoid stacking paralleled by a lower chlorophyll a/h ratio. Overnight malate accumulation was very low. Starch was retained but its day/night fluctuation was practically suppressed. Plastosomes were smaller and fewer, and the range of their daily fluctuation was very reduced. Vacuoles underwent fragmentation and accumulated osmiophilic deposits. The maintenance of the cellular integrity accounts for the ability of C.quadrangularisto recover rapidly from water s

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01563.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractCells of Porphyra umbilicalis show a biphasic osmotic regulatory response. After transfer from 1 × into 3.5 × artificial seawater medium (osmotic upshock) the protoplasts shrink rapidly, then recover their original size within 3 h and continue to increase over the next 14 d. After retransfer from 3.5 × into 1 × medium (osmotic downshock) the protoplasts swell immediately and then adjust to the normal size in 1 x medium. Parallel to the shrinkage of the protoplasts after osmotic upshocks the plasmalemma at first gets a wavy surface which becomes smooth again during the following adaptation process. Immediately after osmotic upshock the vacuolar volume increases and it decreases drastically after osmotic downshock. After osmotic upshocks only small vacuoles are present at first. In adapted plants, however, the vacuolar system is mainly composed of large vacuoles. The volume of the protoplasm without the vacuoles is regulated osmotically. Parallel to the increase in the vacuolar volume after osmotic upshocks there is an increase in the number of intramembraneous particles on the PF‐face of the tonoplast. This high value is reduced rapidly to the original number after osmotic downshock. The findings are discussed in relation to the function of the vacuoles as compartments of inorganic ion accumulation during osmotic adapt

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01564.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe developmental process leading to the formation of the abscisic acid (ABA) induced turion ofSpirodela polyrrhizawas accompanied by a repression of nucleic acid and protein synthesis. DNA synthesis in the developing lurion (induced by 10−4mol m−3ABA) was inhibited within 3h of ABA addition, followed by a repression of protein synthesis after 24 h, while RNA synthesis was not inhibited until 3 d. The inhibitory effect of ABA on protein synthesis was found to be selective and the synthesis of several novel proteins appeared to be induced. These effects were specific to ABA‐sensitive tissue.The relationship between the changes in the protein and mRNA profiles during the development of the turion was investigated. The rapid general inhibition of protein synthesis at early stages of lurion formation could not be accounted for by the level of translatable mRNA, indicating an effect of ABA at the translational level. The specific alteration to the pattern ofin vivolabelled proteins could have resulted, however, from control of the level of specific mRNAs for those particular proteins. Only after 3 d in ABA, when the developing primordium is committed to the turion developmental pathway, is there a total inhibition in the production of mRNA leading to the shutdown of all primary processes and the onset of the irreversible events leading to the dormant

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01565.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractTranspiration ofSalsola kaliL. plants, grown in small pots under controlled environmental conditions, was followed through a drying cycle of the soil. Three different nutrient solutions were used during the preconditioning growth period: control (C), half‐strength Hoagland's nutrient solution; C plus 150mol m−3NaCl; and C plus 150mol m−3KCl. Soil water content at saturation at the beginning of the drying cycle was 20% (w/w). Both NaCl and KCl treatments modified the plants' response to changes in soil water status. The control plants transpired twice as much (per unit leaf dry weight) as the salt‐treated plants, even when the soil was at maximal water capacity. Transpiration of the control plants remained high, until the soil water content declined to 5%. After that stage the stomata of these plants closed abruptly. Transpiration of the salt‐treated plants started decreasing when the soil water content was approximately 16%, and did so gradually until all the available water was depleted. When transpiration was plotted against soil water potential a sharp decline in the transpiration of control plants was observed with the soil water potential decreasing from ‐0.04 to ‐1.2MPa. Transpiration of the salt‐treated plants decreased gradually over a wide range of soil water potential (

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01566.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA new experimental system was devised for the simultaneous measurement of elongation rate and the activity of the spatially separate electrogenic ion pumps of a hypocotyl segment excised from a seedling ofVigna unguiculataL. Walp. under enforced intra‐organ perfusion by artificial solutions. The pathway of the perfusion medium was apoplastic space, including xylem vessels as main routes. The elongation rate of the segment was highly dependent on the perfusion pressure applied. It was possible to increase the growth rate under pressurized perfusion by 10‐30 times as much as that without perfusion. Elongation rate was also dependent on respiration under perfusion, being retarded reversibly by anoxia a few minutes after the activities of the electrogenic ion pumps were stopped. Perfusion pressure had a little influence on the membrane potential (Vpx) below a breakdown level (c. 130 kPa). Perfusion of mannitol or sorbitol solution of appropriate concentration reduced the elongation rate reversi

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01567.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Book Reviews in this article:INTRODUCTORY PLANT PHYSIOLOGY, 2nd edn. By G. RayNoggle&GeorgeJ. FritzPRINCIPLES AND MEASUREMENTS IN ENVIRONMENTAL BIOLOGY. By F. I. Woodward&J. E. SheehyINTERACTIONS BETWEEN NITROGEN AND GROWTH REGULATORS IN THE CONTROL OF PLANT DEVELOPMENT. Edited by M. B. Jackson

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01568.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY