| | 1 | Author
| MarcelA K Jansen, Klaus Pfister | Requires cookie* | | | Title
| Conserved Kinetics at the Reducing Side of Reaction-Center II in Photosynthetic Organisms; Changed Kinetics in Triazine-Resistant Weeds  | | | | Abstract
| The decay o f chlorophyll variable fluorescence after a "single turnover" flash is generally assumed to represent the reoxidation o f the reduced quinone Qa. We have observed that the kinetics o f this decay are very similar in a wide variety o f species. Comparing 28 different spe cies, we found an average half decay time o f 314 ± 4 6 (isec. N o systematic correlations were found between the decay rate and biochemical or physiological specializations such as C 2, C 4 or C A M . This indicates that structural as well as functional factors controlling photosystem II electron transfer between Qa and Qb are highly conserved. Apparently, the freedom for natural structural variations in this region is very limited. Triazine resistant plants, characterized by an altered amino acid sequence o f the D 1 protein, have clearly decreased rates o f Qa/Q b electron transfer. We found an average half decay time o f 946 ± 100 jisec (5 species). However, this three-fold decrease is much less than previously re ported. Therefore, if alterations o f photosystem II electron transfer efficiency contributes to an often reported reduction o f "ecological fitness", this contribution is smaller than was hitherto assumed. | | | |
Reference
| Z. Naturforsch. 45c, 441—4 (1990); received November 27 1989 | | | |
Published
| 1990 | | | |
Keywords
| Chlorophyll Fluorescence, Evolution, Photosystem II, Triazine Resistance, p sb A Conservation | | | |
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| ZNC-1990-45c-0441 | | | | Volume
| 45 | |
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