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1Author    K.H G RuRequires cookie*
 Title    Herbicides which Inhibit Electron Transport or Produce Chlorosis and Their Effect on Chloroplast Development in Radish Seedlings. III. Plastid Pigment and Quinone Composition  
 Abstract    The effect o f DC M U , bentazon, amitrole and SA N 6706 on the form ation o f chloroplast pig­ ments and quinones was investigated using plants that were grown in total darkness or continuous white, red or far-red light. All herbicides assayed affected the formation o f chlorophylls, carotenoids and quinones but DC M U had only minor effects. Like for chlorophylls and carotenoids the form ation o f quinones was most suppressed in plants grown in the presence o f the herbicide in continuous white or red light, but the effect on the formation o f quinones was much lower as com pared to the pigments. The observation that the biosynthesis o f quinones is still m aintained in SA N 6706 treated bleach­ ed plastids which are lacking chlorophylls and carotenoids indicates that quinones are synthesized at the plastitd envelope and stored in the osm iophilic plastoglobuli. Amitrole and SA N 6706 induced a strong chlorosis. It was o f particular interest that chlorosis was also induced by the photosystem II inhibitor bentazon. D C M U was not effective. The inhibi­ tor concentration for 50% inhibition in the chlorophyll and carotenoid content was 5 x l 0 ~6 M for SAN 6706,3 x 10-4 M for am itrole and 10~3 M for bentazon. As already reported by others SA N 6706 treated plants accum ulated phytoene in large amounts. The highest phytoene content was observed in plants that were grown in the dark. A m itrole treat­ ed plants accumulated lycopene. But in addition other carotenoid precursors like phytoene and phjHofluene were also accum ulated. In contrast to phytoene lycopene was only accum ulated in plants that were grown in the light. Particularly for SA N 6706 and amitrole the expression o f the bleaching effect was depending on the light intensity and light quality that was used during plant growth. T he herbicide effect ewas predominantly expressed at higher light intensities and after irradiation with red light. The o b ­ servation that the induction o f chlorosis is very sensitive to red light as com pared to w hite or blue light is suggesting that phytochrom e is involved in the developm ent o f the herbicide toxicity. It also supports that in SA N treated plants chlorophylls are photodecom posed directly by light be­ cause o f the lack o f photoprotecting carotenoids but m ainly /?-carotene in these plastids. Further support for this was given by the demonstration that SA N treated plants w hich were grown at very low light intensities turned green and were photosynthetically active. 
  Reference    Z. Naturforsch. 37c, 642 (1982); received April 5 1982 
  Published    1982 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophylls, Lycopene, Photosystem II H erbicides 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0642.pdf 
 Identifier    ZNC-1982-37c-0642 
 Volume    37 
2Author    Jürgen Feierabend, TheresiaW. Inkelhüsener, Petra Kemmerich, Ulrike SchulzRequires cookie*
 Title    Mechanism of Bleaching in Leaves Treated with Chlorosis-Inducing Herbicides  
 Abstract    Bleaching o f chlorophyll was studied in the leaves of rye seedlings (Secale cereale L.) treated with four chlorosis-inducing herbicides of different potency (weak photodestructions, group 1: aminotriazole, haloxidine; strong photodestructions, group 2: San 6706, difunone). Chlorophyll deficiency and particularly the inactivation of a chloroplast marker enzyme, NADP-dependent glyceraldehyde-3-P dehydrogenase, that occurred in the presence o f group 2 herbicides were stronger in red, than in blue, light. When grown in white light o f low intensity (10 lx) herbicide-treated leaves contained chloro­ phyll, 70 S ribosomes and unimpaired activities o f NADP-dependent glyceraldehyde-3-P de­ hydrogenase. At 10 lx only the leaves treated with SAN 6706 and difunone were strongly carotenoid-deficient but not those treated with group 1 herbicides. After all herbicide treatments 10 lx-grown leaf tissue was, however, not capable o f photosynthetic 0 2-evolution indicating some disorder of photosynthetic electron transport. Leaf segments grown at 10 lx were exposed to a high light intensity o f 30000 lx at either 0 ° C or 30 °C. In treatments with group 1 herbicides chlorophyll accumulation was stopped in bright light at 30 °C but breakdown was not apparent. Only at 0 °C and in the presence of high, growth-reducing, herbicide concentrations chlorophyll was slightly degraded. The RNAs o f the 70S ribosomes were, however, clearly destroyed at 30000 lx and 30 °C in aminotriazole-treated leaves. In leaves treated with group 2 herbicides chlorophyll was rapidly degraded at 30000 lx both at 0 ° C and 30 °C, however, only in the presence of 0 2, indicating a true photooxidative and mainly photochemical nature o f the reactions involved. This chlorophyll breakdown was accompanied by the photodestruction of 70S ribosomes and the inactivation of NADP-glyceraldehyde-3-P dehydrogenase. In treatments with group 1 herbicides photoinactivation o f the latter enzyme did not occur, although it was clearly localized in the bleached plastids, as demonstrated by gradient separation o f organelles. In the presence of group 2 herbicides the chlorosis was originating from a direct photo­ oxidation of chlorophyll, accompanied by a massive destruction o f other plastid constituents and functions. In treatments with group 1 herbicides photodestructions appeared to be much weaker and insufficient to affect chlorophyll directly. Mediated through some photodestructive inter­ ference with obviously more sensitive plastid components, such as their ribosomes, further chlorophyll accumulation was, however, prevented. 
  Reference    Z. Naturforsch. 37c, 898 (1982); received July 7 1982 
  Published    1982 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophyll, Photooxidation, Plastid rRNA 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0898.pdf 
 Identifier    ZNC-1982-37c-0898 
 Volume    37 
3Author    M. Anfred Liitzow, Peter Beyer, Hans KleinigRequires cookie*
 Title    The Herbicide Command Does Not Inhibit the Prenyl Diphosphate-Forming Enzymes in Plastids  
 Abstract    The herbicide Comm and (2-(2-chlorophenyl)m ethyl-4,4-dim ethyl-3-isoxazolidinone) does not affect the in vitro activities o f the plastid enzymes catalyzing the steps leading from isopen­ tenyl diphosphate to geranylgeranyl diphosphate and phytoene, i.e. the isopentenyl diphos­ phate isomerase, prenyl transferase and phytoene synthase. The extractable activities o f these enzymes in herbicide-treated seedlings are also not affected. Nevertheless, the synthesis o f chlorophylls and carotenoids in treated seedlings is severely inhibited in vivo. The mode o f action o f Comm and remains still unknown. 
  Reference    Z. Naturforsch. 45c, 856 (1990); received April 6 1990 
  Published    1990 
  Keywords    Command, Bleaching Herbicide, Prenyl Diphosphates, Carotinoid Formation, Plastids 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0856.pdf 
 Identifier    ZNC-1990-45c-0856 
 Volume    45 
4Author    Gerhard Sandmann, Karl-Josef Kunert, Peter BögerRequires cookie*
 Title    Biological Systems to Assay Herbicidal Bleaching  
 Abstract    Two strains of Scenedesmus acutus were found useful to study the influence of bleaching agents on either the greening process or the fully pigmented algal cell during growth. Both physiological conditions exhibit high sensitivity to bleaching herbicides. With this new assay, contrasting bleach­ ing effects with the same compound can be found allowing differentiation of the herbicidal action of bleaching agents which apparently is a multifunctional one. Furthermore, the I50 can be determined rather rapidly in a simple graphical method by a Dixon plot. A subsequent application of bleaching herbicides to cultures of the fungus Phycomyces blakesleeanus rules out a possible specific action of the compounds assayed on chlorophyll or photosynthetic redox carriers. This latter assay can show whether or not the herbicides synthesis as is the case with difunon or SAN 9789. 
  Reference    Z. Naturforsch. 34c, 1044—1046 (1979); received June 30 1979 
  Published    1979 
  Keywords    Bleaching Herbicides, Algae, Scenedesmus acutus, Wild-type and Mutant 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1044.pdf 
 Identifier    ZNC-1979-34c-1044 
 Volume    34 
5Author    Karl-JosefK. Unert, Peter BögerRequires cookie*
 Title    Influence of Bleaching Herbicides on Chlorophyll and Carotenoids  
 Abstract    Over 24 and 48 hour cultivation periods the influence of SAN 9789 (norflurazon), EMD-IT 5914 (difunon) and fluridone on growth, photosynthetic oxygen evolution and pigment content of the green alga Scenedesmus acutus was determined. Four effects were observed: a) Both carotenoid and chlorophyll formation were inhibited. b) Carotenoids were destroyed in the presence of air, but not nitrogen. The level of chlorophyll, however, did not change. c) ß-(and a-) carotene was markedly decreased in the presence of oxygen. d) Photosynthetic oxygen evolution was decreased with the disappearance of carotenoids. These effects, which are accompanied by reduced growth, are believed to represent primary herbicidal modes of action. The decrease of oxygen evolution is not due to a direct inhibition of photosynthetic electron transport by the herbicides applied. 
  Reference    Z. Naturforsch. 34c, 1047 (1979); received June 30 1979 
  Published    1979 
  Keywords    Bleaching Herbicides, Algae, Scenedesmus acutus, Carotenoids, Chlorophyll, Air/Nitrogen Gassing 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1047.pdf 
 Identifier    ZNC-1979-34c-1047 
 Volume    34 
6Author    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 
7Author    Gerhard Sandmann, IanE. Clarke, PeterM. Bramley, Peter BögerRequires cookie*
 Title    Inhibition of Phytoene Desaturase — the Mode of Action of Certain Bleaching Herbicides  
 Abstract    Assay systems have been developed in order to differentiate betw een the m odes o f action o f certain bleaching herbicides. These include inhibition o f chlorophyll or carotenoid biosynthesis, and initiation o f pigment degradation. H erbicidal com pounds with phytoene desaturase as their primary target site were investigated in a cell-free carotenogenic system from Aphanocapsa. In a comparative study, the structural prerequisites for inh ib ition o f phytoene desaturase were estab­ lished for both benzophenone analogs and various m -phenoxybenzam ides. This inhibitory action o f the latter compounds is enhanced by lipophilic groups with certain steric properties. 
  Reference    Z. Naturforsch. 39c, 443 (1984); received N ovem ber 1 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Cell-Free System, Carotene Biosynthesis, P hytoene Desaturase, Inhibitors 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0443.pdf 
 Identifier    ZNC-1984-39c-0443 
 Volume    39 
8Author    Jürgen FeierabendRequires cookie*
 Title    Comparison of the Action of Bleaching Herbicides  
 Abstract    Among chlorosis-inducing herbicides that interfere with carotenoid synthesis two groups o f different potency can be discriminated (group 1; aminotriazole amd haloxidine; group 2 with more extensive photodestructions: pyridazinone herbicides and difunon). After application o f herbicides o f group 2 colored carotenoids were com pletely absent and preexisting chlorophyll was degraded by photochem ical reactions requiring high light intensity and 0 2, that occurred also at 0 °C . In treatments with group 1 herbicides direct photodegradation o f chlorophyll was not sufficient to generate the chlorosis. Light-induced interference with constituents o f the chloroplast protein synthesis apparatus being more sensitive to ph otooxidative dam age than chlorophyll, appeared to indirectly m ediate the chlorosis. In the absence o f chloroplast protein synthesis further chlorophyll accum ulation is prevented. Photodegradation o f chlorophyll in the presence o f group 2 herbicides involved the participation o f 0 2~ radicals and was accom panied by lipid peroxidation. In all herbicide treatments the catalase activity o f the leaves was very low. Only in the presence o f group 2 herbicides chloroplast enzym es o f cytoplasm ic origin (e.g. NADP-glyceraldehyde-3-phosphate dehydrogenase) were also inactivated. Rapid inactivation o f catalase as well as o f N A D P-glyceraldehyde-3-phosphate dehydrogenase was induced by exposure o f dim-light-grown herbicide-treated leaves to bright light, also at 0 ° C . In treatments with herbicides o f group 2 also other peroxisom al enzymes (e.g. glycolate oxidate, hydroxy-pyruvate reductase) were affected. The elim ination o f these peroxisom al enzym es also appeared to depend on photooxidative processes o f the chloroplast. 
  Reference    Z. Naturforsch. 39c, 450 (1984); received N ovem ber 4 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Carotenoids, Catalase, Chlorosis, Leaf Peroxisom es, Photooxidation 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0450.pdf 
 Identifier    ZNC-1984-39c-0450 
 Volume    39 
9Author    K. H. GrumbachRequires cookie*
 Title    Herbicides which Interfere with the Biosynthesis of Carotenoids and Their Effect on Pigment Excitation, Chlorophyll Fluorescence and Pigment Composition of the Thylakoid Membrane  
 Abstract    Plants grown in the presence o f the herbicides assayed synthesized chlorophylls during growth at low fluence rates. Subsequent irradiation with higher fluence rates o f red light induced a strong chlorosis with SAN 6706 being a much stronger herbicide than J 852 or am ino-triazole. All herbicides assayed also changed the content and com position o f chlorophylls, carotenoids and pigment-protein-complexes o f the thylakoid m em brane and therefore the pigm ent excitation and chlorophyll fluorescence em ission spectra o f the plastid. W ith increasing herbicide toxicity the main characteristic em ission bands at 690 and 730 nm disappeared and new em ission bands at 715 (J 852) and 700 nm (SA N 6706) appeared. Such "artificial" m em branes with a changed pigment composition were very susceptible to light. Presented data m ay be taken as evidence, that the lack o f photoprotective cyclic carotenoids caused by the specific action o f a bleaching herbicide is the primary event that m ay lead to a disturbed form ation o f the thylakoid membrane and its destruction by light and oxygen. 
  Reference    Z. Naturforsch. 39c, 455—458 (1984); received N ovem ber 29 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophylls, F luorescence, Pigm ent Excitation 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0455.pdf 
 Identifier    ZNC-1984-39c-0455 
 Volume    39 
10Author    Gerhard Sandmann, Peter BögerRequires cookie*
 Title    Interference of Dimethazone with Formation of Terpenoid Compounds  
 Abstract    Dimethazone is a bleaching herbicide without any peroxidative activity. In addition to the inhibition of chlorophylls, carotenes, and xanthophylls, decreased formation of other prenyl lipids (phytol and a-tocopherol) can be observed in the presence of dimethazone. Application of this herbicide to pea plants results in the inhibition of longitudinal growth of the newly formed internodes which can be reversed by gibberellic acid. Apparently, dimethazone also decreases the endogenous gibberellin levels. As the formation of all the compounds assayed is inhibited to the same extent and as ho -values for chlorophyll and carotenoid biosynthesis are identical (about 10 |xm dimethazone), the various effects of dimethazone are explained by a single enzyme target in the terpenoid biosynthetic pathway between acetate and geranylgeranyl pyrophosphate. In tro d u ctio n 
  Reference    Z. Naturforsch. 41c, 729 (1986); received April 16 1986 
  Published    1986 
  Keywords    Dimethazone, Bleaching Herbicide, Prenyl Lipids, Terpenoid Formation, Pigment Synthesis 
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 TEI-XML for    default:Reihe_C/41/ZNC-1986-41c-0729.pdf 
 Identifier    ZNC-1986-41c-0729 
 Volume    41 
11Author    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 
12Author    PeterM. Bramley, IanE. Clarke, K., Gerhard Sandmann, Peter BögerRequires cookie*
 Title    Inhibition of Carotene Biosynthesis in Cell Extracts of Phycomyces blakesleeanus  
 Abstract    Cell extracts o f the C l 15 (^-carotene-accum ulating) strain o f Phycom yces blakesleeanus were incubated with either [2-l4C]MVA or [1-I4C]IPP and a range o f possible inhibitors o f caro-tenogenesis, including bleaching herbicides, biphenyl com pounds and geranylacetone. Several o f these compounds were potent inhibitors o f /7-carotene form ation and caused the accum ulation o f phytoene. N o other carotenes were found to accum ulate, in vitro. The structures o f these inhibi­ tors, compared to that o f phytoene, suggest that they affect the enzym ic activity o f "phytoene dehydrogenase", possibly by com petitive inhibition. 
  Reference    Z. Naturforsch. 39c, 460—463 (1984); received N ovem ber 1 1983 
  Published    1984 
  Keywords    Carotenoid Biosynthesis, Bleaching Herbicides, Inhibitors o f Phytoene Desaturation, Phycomyces blakesleeanus, Cell Extracts 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0460.pdf 
 Identifier    ZNC-1984-39c-0460 
 Volume    39