Endosulfan and cypermethrin-induced oxidative stress in plants and their influence on phytoremediation process

MITTON, FRANCESCA; GONZALEZ MARIANA; SHIMABUKURO VALERIA; MONSERRAT JOSE M; MIGLIORANZA KARINA SILVIA BEATRIZ

Milan

Congreso; SETAC Europe 21st Annual Meeting; 2011

SETAC

Phytoremediation involves the use of vegetation for in situ treatment of contaminated soils, sediments, and water. It is applicable at sites containing organic pollutants where plants can uptake and metabolize them and/or enhance the rhizospheric activity. However, some pollutants are known to enhance Reactive Oxygen Species (ROS) formation and it can affect the efficiency of phytoremediation due to toxic effects. ROS produce oxidative damage to proteins, DNA and lipids. Under optimal growth conditions, ROS are produced at a low level in organelles such as chloroplasts, mitochondria and peroxisomes. However, pesticide uptake can dramatically elevate their rate of production. The aim of this work was to study the oxidative stress in edible plants exposed to soils spiked with a mixture of endosulfan and cypermethrin as a measure of plant tolerance for their use in soil phytoremediation. Lipid peroxidation (malondyaldehide content, MDA) and total antioxidant capacity against peroxyl radicals (ACAP) was measure in leaves and roots of soybean, sunflower, colza and alfalfa plants grown in soil spiked with technical endosulfan (Master® 35%, 5 ppm) and cypermethrin (Goti Glex, cis 40-50, 25%, 0.5 ppm) after 15 and 60 days of exposure. Control plants were grown in the same soil without pesticides. Results showed an increase in the ACAP of roots and leaves at 60 days for most species while MDA levels increase only in leaves. These results can indicate that pesticide uptake and translocation may trigger oxidative damage in leaves. However in older plants, growth leads to higher photosynthesis rate and ROS production that enhance the oxidative damage caused by pesticides. Plants grown in contaminated soils showed lower biomass and growth rate than control plants (clean soils) suggesting pesticide toxicity, and the lower MDA levels would be related to changes in lipid types (ie. lower proportion of unsaturated lipids). The knowledge about the induction of oxidative stress by pesticides is necessary for planning phytoremediation strategies and allows selecting tolerant species according to particular sceneries.