Alteration in the metabolism of free radicals in wheat seedlings grown in the presence of 4-chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone.
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Date
1986-09
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Abstract
When wheat seedlings were grown in the presence of 62·5–500 μΜ
4 chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone, an inhibitor of photosystem II
electron transport, there was a marked inhibition of in vivo photosystem II electron
transport as revealed by the analysis of fast chlorophyll a fluorescence transients in intact
leaves and by the inhibition (95% at 500 μM) of net photosynthesis in intact leaves
Accompanying this inhibition of photosystem II electron transport, there was a decrease
in the content of photosynthetic pigments. The extent of lipid peroxidation, measured in
terms of malondialdehyde content was not increased; rather it was found decreased. An
analysis of in vitro lipid peroxidation of the thylakoid membranes of control and
4-chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone treated plants in the presence of a
sensitizer dye (toluidine blue) showed a similar rate both in the control and treated
samples suggesting that the availability of unsaturated fatty acids as a substrate for lipid
peroxidation was not limiting even though it decreased in the treated plants. On the other
hand, it appears that the availability of the free radicals for lipid peroxidation was
decreased byenhanced activity of the enzyme systems involved in the metabolism of free
radicals. Measurements of the activities of enzymes involved in the metabolism of free
radicals showed an increase in the activities of NADPH-glutathione reductase (6–8 fold)
and catalase (15–30%) and a decrease in the activity of superoxide dismutase (30–45%) in
the treated plants.
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Keywords
Triticum vulgare, free radical metabolism, BASF 13.338.
Citation
Mannan R Mannar, Bose Salil. Alteration in the metabolism of free radicals in wheat seedlings grown in the presence of 4-chloro-5-dimethylamino-2-phenyl-3(2H) pyridazinone. Journal of Biosciences. 1986 Sept; 10(3): 283-291.