Absorption and metabolism of clomazone by suspension-cultured cells of soybean and velvetleaf

Abstract Clomazone uptake and metabolism were compared in soybean and velvetleaf suspension cultured cells utilizing either [ 14 C]methylene-clomazone or [ 14 C]carbonyl-clomazone. Velvetleaf cells absorbed more clomazone than soybean did. Cells of both species accumulated more metabolites when treated with [ 14 C]methylene-clomazone than when treated with [ 14 C]carbonyl-clomazone. Higher amounts of [ 14 C]metabolites were present in the media of cells treated with [ 14 C]carbonylclomazone than [ 14 C]methylene-clomazone. Differences in uptake were due to cellular retention of the benzyl moiety and efflux of the heterocyclic moiety after cleavage of clomazone. All metabolites produced in soybean and velvetleaf cells were more polar than clomazone. No qualitative differences in the metabolites produced by soybean and velvetleaf were identified. Both soybean and velvetleaf oxidatively cleaved the clomazone molecule and subsequently conjugated the benzyl moiety with glucose. One of the aglycones was identified as 2-chlorobenzylalcohol. Oxidative cleavage of clomazone was a major metabolic reaction occurring in both the tolerant (soybean) and susceptible (velvetleaf) species.