Biochemical bases for a widespread tolerance of cyanobacteria to the phosphonate herbicide glyphosate |
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Authors: | Forlani Giuseppe Pavan Mauro Gramek Magdalena Kafarski Pawel Lipok Jacek |
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Institution: | Department of Biology and Evolution, University of Ferrara, Italy. flg@unife.it |
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Abstract: | Possible non-target effects of the widely used, non-selective herbicide glyphosate were examined in six cyanobacterial strains, and the basis of their resistance was investigated. All cyanobacteria showed a remarkable tolerance to the herbicide up to millimolar levels. Two of them were found to possess an insensitive form of glyphosate target, the shikimate pathway enzyme 5-enol-pyruvyl-shikimate-3-phosphate synthase. Four strains were able to use the phosphonate as the only phosphorus source. Low uptake rates were measured only under phosphorus deprivation. Experimental evidence for glyphosate metabolism was also obtained in strains apparently unable to use the phosphonate. Results suggest that various mechanisms may concur in providing cyanobacterial strains with herbicide tolerance. The data also account for their widespread ability to metabolize the phosphonate. However, such a capability seems limited by low cell permeability to glyphosate, and is rapidly repressed when inorganic phosphate is available. |
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Keywords: | Cyanobacteria - EPSP synthase - Glyphosate - Herbicide tolerance - Phosphonate/phosphate uptake - Target enzyme-based resistance - Xenobiotic metabolism |
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