ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00492.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe effect of sink‐strength‐reduction on the carbohydrate content in apoplast and symplast of source leaves was examined inPisum sativumL. Sink strength was reduced by removing developing seeds or by means of the ‘open seed coat technique’. After seed removal, an increase in the sucrose content could be observed, especially in the apoplast. Starch content did not change during the course of the experiments. Fixation of14CO2was not influenced by sink‐strength‐reduction. The increase in the sucrose content can be explained as a consequence of a change in the balance between production and export of sucrose in the source leaves. Reduction in phloem loading may have caused an increase in sucrose content in the leaf apoplast, followed by an increase in sucrose in the leaf symplast, without a change in pho

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00493.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYA number of physiological data that led to the conclusion of the existence of a proton/sucrose symporter mediating the uptake of sucrose into the phloem cells were obtained from broad bean (Vicia fabaL.) The present paper investigates the possibility of studying the uptake of solutes at the plasma membrane level in this species in repsonse to an artificially imposed proton‐motive‐force. Plasma membrane vesicles were purified by aqueous two‐phase partitioning from the microsomal fractions of broad bean leaves. The activity of selected marker enzymes showed that the plasma membrane vesicles were at least 90% pure. The imposition of an artificial proton‐motive‐force energized an active (against a concentration gradient) and transient uptake of both sucrose and valine. The maximum uptake rates were comparable for both sucrose and valine; sucrose was accumulated 6·2 times and valine 5·6 times above the diffusion equilibrium. The uptake of sucrose was saturable suggesting that the uptake was carrier‐mediated. The affinity of the sucrose carrier for its substrate was 0·6 mmunder energized conditions. These results confirm with a new material the possibility of studying proton‐coupled transport of solutes directly at the membrane level, and are compared with data available fr

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00494.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe effects of abscisic acid (ABA) on the uptake of sucrose into discs from tobacco (Nicotiana tabacum) source leaves were studied. ABA stimulated an increase in sucrose uptake up to three‐fold, depending on the osmotic potential of the medium. Maximal stimulation was observed around 200 mOsm, and at 1 μmABA. A tentative explanation for the discrepancy between these results and the previously described inhibition by ABA of sucrose uptake into leaf discs from other plant species is present

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00495.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYWax surfaces of current, first and second year needles ofPinus sylvestris L. from Open Top Chambers, both fumigated with ammonia and unfumigated, were examined with the scanning electron microscope. In the course of time the wax rodlets on peristomatal rims of treated and untreated plants became fused and agglomerated to various extents into morphologically different types of crusts. Compact peristomatal crusts were most frequent. Porous, particulate and ‘melted’ peristomatal crusts as well as epistomatal crusts were of rare occurrence and presumably represented a random phenomenon. No correlation was found between appearance of wax crusts and ammonia fumigation. Ammonia treatment did not affect fungal growth either. Quantitative estimates indicated a very weak, statistically insignificant, tendency of ammonia to increase the rate of the normal, age dependent wax degradation. Observations on young needles developing after prolonged fumigation are suggestive of an indirect effect of ammonia on the rate of crystalline wax degradat

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00496.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe bryoflora and angiosperm flora in one of the main desert wadis, in the State of Kuwait on the western side of the Arabian Gulf, has been studied during two periods separated by an interval of 9 years. The first period lasted for four successive seasons; 1974/75–1977/78. The second period lasted for only three successive seasons; 1987/88–1989/90. Drastic changes both in rate of growth and diversity of the bryoflora and angiosperm flora were observed and recorded. These changes, which are due mainly to successive years of drought, are described here and discussed in det

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00497.x

年代:1992

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00498.x

年代:1992

数据来源: WILEY

摘要:

Modern Concepts inPenicilliumandAspergillusClassificationR.A. Sampson and J.I. Pitt (eds). Plenum Press, New York and London, NATO Scientific Affairs Div. 1990. ix + 478 pp. Illustrated, hardback. US$115.00. ISBN 0‐306‐4315

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00500.x

年代:1992

数据来源: WILEY

摘要:

The Rhizosphere and Plant Growth. Beltsville Symposia in Agricultural Research 14D.L. Keister and P.B. Cregan (eds) Kluwer Academic Publishers, Dordrecht. 1991. xii + 386 pp. Illustrated, hard cover. Dfl.300.00, UK £103.00, US$196.00. ISBN 0‐7923‐10

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00503.x

年代:1992

数据来源: WILEY

摘要:

Leaf Venation Patterns Volume 5. CombretaceaeE.P. Klucking. J. Cramer (Borntraeger), Berlin. 1991. 219 pp. Illustrated, hard cover. DM240.00. ISBN 3‐443‐5001

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00505.x

年代:1992

数据来源: WILEY