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Updated: Jul 15, 2026

Protocols for Robust Herbicide Resistance Testing in Different Weed Species
Published on: July 2, 2015
Discovery and directed evolution of a glyphosate tolerance gene
Linda A Castle1, Daniel L Siehl, Rebecca Gorton
1Verdia, Inc. Redwood City, CA 94063, USA. linda.castle@verdiainc.com
Abstract:
The herbicide glyphosate is effectively detoxified by N-acetylation. We screened a collection of microbial isolates and discovered enzymes exhibiting glyphosate N-acetyltransferase (GAT) activity. Kinetic properties of the discovered enzymes were insufficient to confer glyphosate tolerance to transgenic organisms. Eleven iterations of DNA shuffling improved enzyme efficiency by nearly four orders of magnitude from 0.87 mM-1 min-1 to 8320 mM-1 min-1. From the fifth iteration and beyond, GAT enzymes conferred increasing glyphosate tolerance to Escherichia coli, Arabidopsis, tobacco, and maize. Glyphosate acetylation provides an alternative strategy for supporting glyphosate use on crops.
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