Cysteine proteases are activated in sensitive <i>Amaranthus palmeri</i> populations upon treatment with herbicides inhibiting amino acid biosynthesis

Abstract The herbicides glyphosate and pyrithiobac inhibit the enzyme 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) in aromatic amino acid biosynthetic pathway acetolactate (ALS) branched‐chain pathway, respectively. Here we characterise protease activity profiles of a sensitive (S), glyphosate‐resistant (GR) multiple‐resistant (MR) population Amaranthus palmeri response to pyrithiobac. Amino accumulation cysteine activities were induced with both S GR population, suggesting that increase proteases is responsible for increased degradation available proteins observed free acids. Herbicides did not induce any changes proteolytic populations target‐site resistance, indicating this effect was only plants.