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'Photosystem II Herbicides' in keywords
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1982 (2)
1980 (2)
1Author    K. H. GrumbachRequires cookie*
 Title    Herbicides which Inhibit Electron Transport or Produce Chlorosis and Their Effect on Chloroplast Development in Radish Seedlings I. Chlorophyll a Fluorescence Transients and Photosystem II Activity  
 Abstract    Diuron and bentazon are very strong inhibitors o f the photosynthetic electron transport in isolated radish chloroplasts. The chlorosis producing herbicide SAN 6706 also inhibited the photosystem II dependent oxygen evolution. Aminotriazole had no effect. The inhibitor concentration for 50% inhibition o f photosystem II activity was 10-7 m for diuron and 10-4 m for bentazon and SAN 6706 respectively. Diuron and bentazon quenched the chlorophyll a fluorescence transients in isolated radish chloroplasts drastically, while aminotriazole was not effective. It was o f particular interest that the bleaching herbicide SAN 6706 inhibited photosystem II dependent oxygen evolution in a similar concentration as bentazon but had no effect on the chlorophyll a-fluorescence transients suggesting that SAN 6706 is not binding to the same site o f the electron transport chain as diuron and bentazon. Apart from their direct influence on electron transport in isolated photosynthetically active chloroplasts the photosystem II and bleaching herbicides assayed also strongly affected photosynthesis in radish seedlings that were grown in the presence o f the herbicides for a long time. As already obtained using isolated chloroplasts, photosystem II dependent oxygen evolution like the chlorophyll a fluorescence transients were strongly inhibited by the photosystem II herbicides diuron and bentazon. A reduction but no inhibition o f photosystem II activity was observed in plants that were grown in the presence o f aminotriazole. The pyridazinone SAN 6706 was behaving contradictory. In partly green plants photosystem II activity was still maintained and even higher than in untreated plants while in albinistic plants no photosynthetic activity was detected. 
  Reference    Z. Naturforsch. 37c, 268—275 (1982); received December 3 1981 
  Published    1982 
  Keywords    Bleaching Herbicides, Photosynthesis, Photosystem II Herbicides, Photosystem II Activity, Chlorophyll Fluorescence 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0268.pdf 
 Identifier    ZNC-1982-37c-0268 
 Volume    37 
2Author    K. H. Grumbach, M. DrollingerRequires cookie*
 Title    The Effect of Phytochrome and Proteinsynthesis-Inhibitors on the Formation of Chlorophylls and Carotenoids in Radish Seedlings Treated with Photosystem II and Bleaching Herbicides  
 Abstract    Etioplasts of radish seedlings treated with photosystem II (DCM U, bentazon) and chlorotic herbicides (amitrole, SAN 6706) were tested on their ability to perform the phytochrome mediated chlorophyll and carotenoid biosynthesis. The cytoplasmic influence on the chloroplastic action o f herbicides was also investigated by inhibition of protein synthesis either in the chloro­ plast with chloramphenicol or in the cytoplasm with actidion. In all herbicide treated radish seedlings a phytochrome mediated chlorophyll and carotenoid biosynthesis was obtained as found in control plants. In plants treated with DCM U the bio­ synthesis o f carotenoids is enhanced compared to the control plants, while SAN 6706 significantly suppresses the carotenoid formation. It is concluded, that photosystem II and chlorotic herbicides do not interfere with the primary action o f phytochrome but rather do develope their effects on the terpenoid metabolism through phytochrome. Chloramphenicol applied at the time o f sowing very strongly suppresses the formation of chlorophylls and carotenoids in control plants. The sensitivity towards actidion is, however, very much lower. If chloramphenicol and actidion treated plants were also supplied with herbicides, the pigment pattern is completely different In SAN 6706-treated plants chloramphenicol acts synergistic, resulting in an even lower chlorophyll and carotenoid content than in plants supplied only with chloramphenicol. On the other hand SAN 6706 in combination with actidion enhances the formation of pigments, leading to a much higher chlorophyll and carotenoid content as in plants treated only with actidion. A stimulatory effect on the formation o f chlorophylls and carotenoids was also found for DCMU-treated plants in combination with actidion. The observation, that in plants treated with SAN 6706 together with actidion, which inhibits protein synthesis in the cytoplasm, the herbicidal response in the chloroplast is completely abolished, gives evidence that the photooxidative action of SAN 6706 in the chloroplast is developed by the cytoplasm. 
  Reference    Z. Naturforsch. 35c, 445 (1980); received February 8 1980 
  Published    1980 
  Keywords    Photosystem II Herbicides, Chlorotic Herbicides, Chlorophylls, Carotenoids, Phytochrome, Inhibitors 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0445.pdf 
 Identifier    ZNC-1980-35c-0445 
 Volume    35 
3Author    D. Meier, H. K. Lichtenthaler, G. BurkardRequires cookie*
 Title    Change of Chloroplast Ultrastructure in Radish Seedlings under the Influence of the Photosystem II-Herbicide Bentazon  
 Abstract    The influence of the photosystem II-herbicide bentazon on the ultrastructure o f chloroplasts o f radish seedlings (Raphanus sativus L.) was investigated with special emphasis on thylakoid developm ent and grana formation. Bentazon application (10-3 m) induces the formation of broader and higher grana stacks (grana width: 0 .5 -0 .6 n m ; greatest frequency: 3 -8 thylakoids per granum) than in the control plants (grana width: 0.3 |im; greatest frequency: 2 -4 thylakoids per granum). Furtherm ore, the am ount of chloroplast lamellae is enhanced, as are the stacking degree of thylakoids and the grana area. The chloroplasts of bentazon-treated plants appear to be shorter and thicker than in the controls and show all signs of a shade-type adaptation of the photosynthetic apparatus. 
  Reference    Z. Naturforsch. 35c, 656 (1980); received March 17 1980 
  Published    1980 
  Keywords    Bentazon, Chloroplast-Ultrastructure, G rana Form ation, Photosystem II-Herbicide, Shade-type Chloroplasts 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0656.pdf 
 Identifier    ZNC-1980-35c-0656 
 Volume    35 
4Author    C. Buschm, K.H G RuRequires cookie*
 Title    Herbicides which Inhibit Electron Transport or Produce Chlorosis and Their Effect on Chloroplast Development in Radish Seedlings II. Pigment Excitation, Chlorophyll Fluorescence and Pigment-Protein Complexes  
 Abstract    DCM U, bentazon, amitrole and SA N 6706 affected the form ation o f the pigm ent-protein com ­ plexes and caused drastic alterations in the absorption o f light and in the transfer o f the absorbed energy in the antennae systems. Bentazon and D C M U , photosystem II inhibitors, did not change the pigment absorption and fluorescence excitation spectra. After application o f both herbicides the long wavelength fluorescence em ission band at 740 nm was reduced sim ilar as in young d e ­ veloping leaves. Although D C M U and bentazon inhibit the photosynthetic electron transport at the same site, bentazon mainly suppressed the form ation o f the photosystem I com plexes C P Ia and CPI while DC M U mainly reduced the photosystem II com plex CPa. Bentazon specifically en­ hanced the formation o f LHCP3. This may be im portant for the increased grana stacking in plas-tids from bentazon treated plants. The bleaching herbicides amitrole and SA N 6706 inhibited the form ation o f carotenoids lead ­ ing to an accumulation o f lycopene, phytofluene and phytoene, w hile the accum ulation o f chloro­ phylls was suppressed. This bleaching effect was m ost pronounced during growth under higher intensities o f light. In weak light (100 lux) am itrole reduced the long wavelength fluorescence maximum but the fluorescence excitation was not affected. W ith am itrole at 2000 lux and SAN 6706 at 100 lux the long wavelength em ission band was further decreased and the fluores­ cence excitation spectra point to a less efficient energy transfer to chlorophyll a. The fluorescence spectra changed due to herbicide treatment resem bled those o f not yet fully developed leaves. In contrast to the photosystem II herbicides the bleaching herbicides am itrole and SA N 6706 had a similar effect on the formation o f pigm ent-protein com plexes. After growth at 2000 lux both herbicides suppressed the formation o f the photosystem I com plex C P Ia and the photosystem II complex CPa. At 100 lux only the formation o f C P Ia was affected. Except for D C M U all herbicides assayed primarily changed the form ation o f photosystem I. 
  Reference    Z. Naturforsch. 37c, 632 (1982); received April 2 1982 
  Published    1982 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophylls, C hlorophyll Fluorescence, Photosystem II Herbicides, Pigm ent-Protein-Complexes 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0632.pdf 
 Identifier    ZNC-1982-37c-0632 
 Volume    37