In vivo and in vitro metabolism of bentazon
- USDA-ARS, Raleigh, NC (USA)
- USDA-ARS, Raleigh, NC (USA) North Carolina State Univ., Raleigh (USA)
- North Carolina State Univ., Raleigh (USA)
The metabolism of the herbicide bentazon was studied using excised shoots and microsomal preparations from 4-day-old Sorghum bicolor seedlings. Excised seedlings were incubated with ({sup 14}C)bentazon over a 4 hr time course. The tissue was extracted with methanol and the extract subjected to HPLC. Sorghum seedlings produced a single time-dependent metabolite, that upon hydrolysis with {beta}-glucosidase, yielded a product that co-chromatographed with 6-OH bentazon. Tetcyclacis, a known inhibitor of cytochrome P450 monooxygenase activity, inhibited bentazon metabolism but not uptake in sorghum seedlings. Microsomes were prepared from sorghum seedlings by differential centrifugation. When assayed with ({sup 14}C)bentazon, the microsomes produced a single bentazon metabolite that co-migrated with 6-OH bentazon using HPLC. Metabolite formation was linear for 45 min. Formation of the metabolite in microsomes required NADPH and oxygen, and was inhibited by CO. Saturation kinetics of bentazon hydroxylation were determined and a K{sub m} of 68 {mu}M was calculated. Metabolite formation was completely inhibited by 10 {mu}M tetcyclacis, whereas 100 {mu}M PBO, 40 {mu}M tridiphane and 100 {mu}M 1-ABT caused minor or no inhibition of hydroxylation. These data suggest that bentazon hydroxylation by sorghum in vivo and in vitro is mediated by a cytochrome P450 monooxygenase.
- OSTI ID:
- 5841308
- Report Number(s):
- CONF-9007196--
- Journal Information:
- Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 93:1; ISSN PPYSA; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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