Effect of herbicides on the activity of antioxidant enzymes and ALA-D in transgenic hybrid corn

Abstract

A corn cultivar with resistance to 2,4-D, glyphosate, ammonium-glufosinate, and haloxyfop-R has been developed. However, it is known that the application of herbicides generally induces the accumulation of reactive oxygen species (ROS), which can cause oxidative damage to plants. In this study, we applied these herbicides in Enlist™ corn hybrids, in the doses recommended for weed control of herbicides alone and in mixtures, being 0, 670, 1080 400, and 60 g ha-1 a.e. of glyphosate, 2,4-D, ammonium-glufosinate, and haloxyfop-R, respectively. The experiment was conducted in a greenhouse at Universidade Federal da Fronteira Sul (UFFS), Erechim, RS, Brazil. The plants were grown in a soil and substrate mix (proportion of 1:1), in plastic vases (0.5 L). The design was completely randomized, with four replicates and two plants per replicate. The herbicides were sprayed 22 days after corn emergence (V2 stage). At seven days after the application, all plants were collected and macerated, then maintained in an ultra-freezer at -80 ºC until the biochemical analysis could be performed. The activity of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), ALA-D and the lipid peroxidation levels were evaluated to know the effects of herbicide application in these plants. The herbicides, especially the mixtures, increased the activity of the antioxidant enzymes that decompose H2O2, such as CAT and APX, and also caused an inhibition of the activity of GPX and ALA-D while promoting lipid peroxidation. This may be associated with the increased generation of H2O2, which was added to the production of other ROS, causing an overload of the antioxidant defense system of transgenic corn, resulting in damage to plant lipids