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Effect of Pyridazinone Herbicides on Lipid Metabolism in Groundnut (Arachis hypogaea) Leaves

Rajasekharan, R and Sastry, PS (1987) Effect of Pyridazinone Herbicides on Lipid Metabolism in Groundnut (Arachis hypogaea) Leaves. In: Pesticide Biochemistry and Physiology, 29 (2). pp. 163-175.

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The effect of five substituted pyridazinones (pyrazon, San 133-410H, San 9774, norflurazon, and San 6706) on lipid metabolism in groundnut (Arachis hypogaea) leaves was investigated under nonphotosynthetic conditions. In experiments with leaf disks, the uptake of $[1-$$^{14}C]$acetate, $[^{32}P]$orthophosphate, and $[^{35}S]$sulfate was significantly inhibited by these herbicides and the magnitude of inhibition varied, depending on the substituents. When the incorporation of these precursors into lipids was measured and expressed as percentage of total uptake, no effect was observed in the case of $[1-$$^{14}C]$acetate but there was significant inhibition in the incorporation of the other 2 precursors, suggesting that pyridazinones interfere with the metabolism of the phospholipids and the sulfolipid. None of these compounds affected the uptake of $[methyl-$$^{14}C]$choline but all inhibited its incorporation into phosphatidylcholine indicating that phosphatidylcholine metabolism is vulnerable to pyridazinones. The fatty acid synthetase of isolated chloroplasts assayed in the absence of light was inhibited 20-50% by the pyridazinones at 0.1-0.5 mM concentrations. San 9774 showed the most potent inhibition. In addition, the pyridazinone herbicides significantly inhibited sn-glycerol-3-phosphate acyltransferase(s) in both chloroplast and microsomal fractions but showed no effect on phosphatidic acid phosphatase. The magnitude of inhibition of fatty acid synthetase and acyltransferase(s) is related to the nature of the substituent groups on the herbicide. Trifluorophenyl substitution at position 2 or amino substitution at position 5 of the pyridazinone mol. caused the maximum inhibitory effect.

Item Type: Journal Article
Publication: Pesticide Biochemistry and Physiology
Publisher: Elsevier Inc
Additional Information: Copyright of this article belongs to Elsevier Inc.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 17 Mar 2008
Last Modified: 19 Sep 2010 04:43
URI: http://eprints.iisc.ac.in/id/eprint/13217

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