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1,3,7-Trimethylxanthine an allelochemical from seeds of Coffea arabica: some aspects of its mode of action as a natural herbicide

by Rizvi, S.J.H; Rizvi, V; Mukerjee, D; Mathur, S.N.
Publisher: 1987ISSN: 0032-079X.Subject(s): COFFEA ARABICA | SEMILLAS | ALELOPATIA | AMARANTHUS SPINOSUS | AMILASAS | SUSTANCIAS TOXICAS | 1,3,7-TRIMETHYLXANTHINE | HERBICIDAS | FITOTOXICIDAD | NITRATO REDUCTASA | ACTIVIDAD ENZIMATICA | VIGNA MUNGO | ACIDO GIBERELICO | BIOQUIMICA | COFFEA ARABICA | SEED | ALLELOPATHY | AMARANTHUS SPINOSUS | AMYLASES | TOXIC SUBSTANCES | HERBICIDES | PHYTOTOXICITY | NITRATE REDUCTASE | ENZYME ACTIVITY | VIGNA MUNGO | GIBBERELLIC ACID | BIOCHEMISTRY | COFFEA ARABICA | SEMENCE | ALLELOPATHIE | AMARANTHUS SPINOSUS | AMYLASE | SUBSTANCE TOXIQUE | HERBICIDE | PHYTOTOXICITE | NITRATE REDUCTASE | ACTIVITE ENZYMATIQUE | VIGNA MUNGO | ACIDE GIBBERELLIQUE | BIOCHIMIE In: Plant and Soil (Países Bajos) v. 98(1) p. 81-91Summary: Certain aspects of selective toxicity of 1,3,7-trimethylxanthine (1,3,7-T), a natural herbicide, were studied in Phaseolus mungo and Amaranthus spinosus. Treatment of seeds of A. spinosus with 1,3,7-T (sub-lethal concentration) caused a marked decrease (29.5 per cent) in amylase activity. Kinetic studies with respect to substrate saturation and Km values as well as in vitro treatments of the cell-free enzyme indicated no effect on its catalytic property. The inhibitory effect of 1,3,7-T on amylase activity could not be counteracted with treatments of GA subindex 3. A general biochemical analysis revealed that the starch/sugar ratio increased in the seedlings grown from treated seeds. Analysis also showed a higher ratio for insoluble/soluble nitrogen. It is suggested that inhibition of germination is caused by reduced synthesis of amylase which is not mediated through gibberelic acid. Treatment of seeds of Phaseolus mungo with 1,3,7-T, caused no change in amylase activity, in vivo nitrate reductase activity, ethanol soluble and insoluble nitrogen and protein content
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++ 6 tab. 36 ref. Sum. (En)

Certain aspects of selective toxicity of 1,3,7-trimethylxanthine (1,3,7-T), a natural herbicide, were studied in Phaseolus mungo and Amaranthus spinosus. Treatment of seeds of A. spinosus with 1,3,7-T (sub-lethal concentration) caused a marked decrease (29.5 per cent) in amylase activity. Kinetic studies with respect to substrate saturation and Km values as well as in vitro treatments of the cell-free enzyme indicated no effect on its catalytic property. The inhibitory effect of 1,3,7-T on amylase activity could not be counteracted with treatments of GA subindex 3. A general biochemical analysis revealed that the starch/sugar ratio increased in the seedlings grown from treated seeds. Analysis also showed a higher ratio for insoluble/soluble nitrogen. It is suggested that inhibition of germination is caused by reduced synthesis of amylase which is not mediated through gibberelic acid. Treatment of seeds of Phaseolus mungo with 1,3,7-T, caused no change in amylase activity, in vivo nitrate reductase activity, ethanol soluble and insoluble nitrogen and protein content

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