George Giannakopoulos1, Jan Dittgen2, Wolfgang Schulte2, Peter Zoellner3, Hendrik Helmke2, Andreas Lagojda4, Robert Edwards1. 1. Crop Protection group, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK. 2. Weed Control Research, Bayer AG, Frankfurt, Germany. 3. Small Molecules Technologies, Bayer AG, Frankfurt, Germany. 4. Structure Elucidation, Environmental Safety, Development, Bayer AG, Monheim, Germany.
Abstract
BACKGROUND: Safeners extend the application of existing herbicides by selectively enhancing tolerance in large-grained cereal crops. While their activity is linked to enhanced herbicide metabolism, their exact mode of action and reasons for their crop specificity have yet to be determined. In this study, we have investigated the selectivity of the recently developed sulfonamide safener cyprosulfamide (CSA), in maize (Zea mays L.) and wheat (Triticum aestivum), focussing on its uptake, distribution and metabolism in the two species. RESULTS: CSA protected maize, but not wheat, from injury by thiencarbazone-methyl (TCM). This correlated with the selective enhanced detoxification of the herbicide in maize, while CSA displayed increased mobility and translocation in wheat. CSA underwent more rapid metabolism in maize than in wheat, with the formation of a specific hydroxylated metabolite correlating with safening. Studies with the nsf1 mutant sweetcorn line showed that the hydroxylation of CSA was partly mediated by the cytochrome P450 CYP81A9. Primary metabolites of CSA were chemically synthesised and tested for their ability to safen TCM in maize. All metabolites tested were inactive as safeners. CONCLUSION: The results of this study suggest that the protection against TCM injury by CSA is linked to enhanced herbicide metabolism. This selective activity is due to the specific recognition of parent CSA in maize but not in wheat. Subsequent rapid oxidative metabolism of CSA led to its inactivation, demonstrating that cytochrome P450s regulate the activity of safeners as well as herbicides. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
BACKGROUND: Safeners extend the application of existing herbicides by selectively enhancing tolerance in large-grained cereal crops. While their activity is linked to enhanced herbicide metabolism, their exact mode of action and reasons for their crop specificity have yet to be determined. In this study, we have investigated the selectivity of the recently developed sulfonamide safener cyprosulfamide (CSA), in maize (Zea mays L.) and wheat (Triticum aestivum), focussing on its uptake, distribution and metabolism in the two species. RESULTS:CSA protected maize, but not wheat, from injury by thiencarbazone-methyl (TCM). This correlated with the selective enhanced detoxification of the herbicide in maize, while CSA displayed increased mobility and translocation in wheat. CSA underwent more rapid metabolism in maize than in wheat, with the formation of a specific hydroxylated metabolite correlating with safening. Studies with the nsf1 mutant sweetcorn line showed that the hydroxylation of CSA was partly mediated by the cytochrome P450 CYP81A9. Primary metabolites of CSA were chemically synthesised and tested for their ability to safen TCM in maize. All metabolites tested were inactive as safeners. CONCLUSION: The results of this study suggest that the protection against TCM injury by CSA is linked to enhanced herbicide metabolism. This selective activity is due to the specific recognition of parent CSA in maize but not in wheat. Subsequent rapid oxidative metabolism of CSA led to its inactivation, demonstrating that cytochrome P450s regulate the activity of safeners as well as herbicides. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Authors: Melissa Brazier-Hicks; Sara Franco-Ortega; Philip Watson; Blandine Rougemont; Jonathan Cohn; Richard Dale; Tim R Hawkes; Alina Goldberg-Cavalleri; Nawaporn Onkokesung; Robert Edwards Journal: ACS Omega Date: 2022-05-11
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