| | 1 | Author
| H. Gimmler, B. Heilmann, B. Demmig, W. Hartung | Requires cookie* | | | Title
| The Permeability Coefficients of the Plasmalemma and the Chloroplast Envelope of Spinach Mesophyll Cells for Phytohormones  | | | | Abstract
| The uptake of auxin (LAA), abscisic acid (ABA) the synthetic cytokinin benzylaminopurine (BA), gibberellic acid (GA3) and mevalonic acid (lactone) (MVA) into intact chloroplasts and protoplasts from spinach mesophyll cells was measured and the permeability coefficients Ps of the chloroplast envelope and the plasmalemma were calculated. With all solutes tested uptake and P s values were considerably higher in the chloroplast system than in the protoplast system. At an external pH of 7.0, rates of uptake exhibited the order BA > LAA > MVA > ABA > GA3 in both systems. However, the P s values (corrected for the undissociated species of the solutes) exhibited the order LAA > GA3 > (ABA or BA) > MVA. This corrected sequence indicates the theoretical capacity of penetration under the assumption that preferentially the protonated species of phytohormones are capable of readily penetrating membranes. P s values for phytohormones appeared largely to be determined by the distribution coefficient K d and to a lesser extent by the molecular weight (Mr). In the Collander-plot the relation between the logarithm of Ps values for phytohormones and some other solutes such as acetate, glycerol, glucose, sorbitol and sucrose and the logarithm of K J M T 1.5 approached linearity. | | | |
Reference
| Z. Naturforsch. 36c, 672—678 (1981); received March 9 1981 | | | |
Published
| 1981 | | | |
Keywords
| Chloroplast Envelope, Permeability Coefficients, Phytohormones, Plasmalemma, Spinach | | | |
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| default:Reihe_C/36/ZNC-1981-36c-0672.pdf | | | | Identifier
| ZNC-1981-36c-0672 | | | | Volume
| 36 | |
| 2 | Author
| Angela Weber, Elke Fischer, Helmut Schipp Von Branitz, Ulrich Lüttge | Requires cookie* | | | Title
| The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species I. Effects on the Electrical Membrane Potential and Alanine Uptake | | | | Abstract
| Sethoxydim is a postemergence herbicide used to control grass weeds. Application at concen-trations higher than 0.1 mM to leaf segments of the sensitive grass species Poa pratensis and Festuca ovina and the tolerant species Poa annua and Festuca rubra, caused a reduction of the electrical membrane potential (AE). The depolarization was reversible and depended linearly on the herbicide concentration. The passive diffusion component of AE was not affected by sethoxy-dim indicating that the herbicide did not change passive permeability characteristics of the plas-malemma. Consequently sethoxydim reduced the active component of AE that depended on primary active transport processes across the plasmalemma. Moreover, sethoxydim increased the reduction of AE of grass leaf cells that was associated with the onset of H + -amino acid cotrans-port. Simultaneously the uptake of alanine into leaf segments was reduced. From these results it had to be concluded that the plasmalemma-bound H + -ATPase was inhibited by sethoxydim in sensitive and tolerant grasses. In vitro ATP hydrolysis of plasmalemma vesicles isolated from grass leaves by polymer phase partitioning, however, was not inhibited by sethoxydim. Apparent-ly another primary active transport mechanism that may contribute to an electrochemical H + -gradient across the plasmalemma, i.e. a plasmalemma-bound redox system, should be the site of inhibition responsible for the membrane effects of sethoxydim observed in vivo. | | | |
Reference
| Z. Naturforsch. 43c, 249—256 (1988); received December 23 1987 | | | |
Published
| 1988 | | | |
Keywords
| Plasmalemma, Membrane ATPase, Herbicide, Sethoxydim, Amino Acid Uptake | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0249.pdf | | | | Identifier
| ZNC-1988-43c-0249 | | | | Volume
| 43 | |
| 3 | Author
| Angela Weber, Ulrich Lüttge | Requires cookie* | | | Title
| The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species II. Effects on Membrane-Bound Redox Systems in Plant Cells | | | | Abstract
| Leaf slices of sethoxydim-sensitive (Poa pratensis, Festuca ovina) and tolerant (Poa annua, Festuca rubra) grass species were found to be able to reduce extracellular ferricyanide by electron transport across the plasmalemma. This reduction was inhibited by the herbicide sethoxydim, and the sensitive species were much more strongly affected than the tolerant ones. The inhibition was concentration dependent. Sethoxydim affected the electron transport in isolated Poo chloroplasts. Polarographic and photometric measurements of ferricyanide reduction suggested photosystem II to be the site of action. Inhibition occurred only in the sensitive species Poa pratensis and was linearly dependent on concentration. In isolated mitochondria from sensitive Zea mays coleop-tiles sethoxydim also acted as an inhibitor of electron transport. Only slight inhibition was meas-ured with mitochondria from tubers of tolerant potato (Solanum tuberosum). It is concluded that sethoxydim generally acts as inhibitor of membrane-bound redox systems. The specific inhibition of the plasmalemma-bound redox system of sethoxydim-sensitive plants could contribute to a selective action of the herbicide. | | | |
Reference
| Z. Naturforsch. 43c, 257—263 (1988); received December 23 1987 | | | |
Published
| 1988 | | | |
Keywords
| Sethoxydim, Herbicide, Redox Systems, Isolated Organelles, Plasmalemma | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0257.pdf | | | | Identifier
| ZNC-1988-43c-0257 | | | | Volume
| 43 | |
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