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'Photosystem II H erbicides' in keywords Facet   Publication Year 1982  [X]
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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