Activity of 5-enolpyruvylshikimate-3-phosphate synthase in glyphosate treated and untreated barley

Abstract

EPSPS (5-enolpyruvilshikimate-3-phosphate syn-thase) inhibition has been described as the main target for the herbicide glyphosate. Total soluble protein concentration and EPSPS activity were measured after 4 hr, 1 day and 7 day of glyphosate treatment, at a dose equivalent to 0.94 Kg ha-1. After seven days of glyphosate treatment, EPSPS activity reduced to 80% as compared to the activity in untreated seedlings. Glyphosate at 2 μM concentration inhibited EPSPS by 18% at a PEP concentration of 1 mM, but inhibition increased to 64% when PEP concentration was 0.1 mM. Moreover, 1.5 μM glyphosate concentration reduced EPSPS activity by 50% at 0.1 mM of PEP, instead 0.1 mM of glyphosate was necessary when 1 mM was present in the reactions.