Glyphosate tolerance can be conferred by decreasing the herbicide's
ability to inhibit the enzyme 5-enolpyruvylshikimate-3-phosphate
synthase, which is essential for the biosynthesis of aromatic amino
acids in all plants, fungi, and bacteria.
Glyphosate tolerance is based upon the expression of the double
mutant 5-enolpyruvylshikimate-3-phosphate synthase (2mEPSPS)
protein. The 2mEPSPS protein, with a lower binding affinity for
glyphosate, is highly resistant to inhibition by glyphosate and
thus allows sufficient enzyme activity for the plants to grow in
the presence of herbicides that contain glyphosate.