Effect of additionally BCAA supply on imazamox-treated sunflower and antioxidative defense system

Sunflower is an economically important oilseed crop worldwide and weeds have a negative effect on its yields. The herbicide imazamox, combined with imazamox-resistant (IMI-R) sunflower hybrids, is a technology known as the Clearfield production system and successfully controls weeds. The mechanism of action of the herbicide imazamox is related to blocking the AHAS enzyme, which catalyzes the first step in the biosynthetic pathway of the branched-chain amino acids (BCAA). In the present study, we investigated the effect of the supplementary addition of BCAA to imazamox-treated IMI-R sunflower plants and antioxidative metabolism. Our results showed that the additional application of BCAA has a beneficial effect on both the total protein content and the activity of the antioxidant defense system of plants. This amelioration is probably a secondary effect of the enhanced protein metabolism and the supposed direct involvement of the three amino acids in the overall protein turnover.