The different responses of glutathione-dependent detoxification pathway to fungicide chlorothalonil and carbendazim in tomato leaves.

Chlorothalonil (CHT) and carbendazim (CAR) are two widely used fungicides in agriculture. Despite their agronomic importance in pest control, little is known about their detoxification in the plant. In this study, we investigated the effects of these fungicides on glutathione (GSH) content, GSH-dependent enzyme activities and gene expression in tomato leaves. Results showed that exposure to CHT resulted in increases in GSH content, activities of glutathione S-transferases (GSTs) and glutathione reductase (GR), as well as the transcriptional levels of glutathione S-transferase genes (GST1, GST2 and GST3), glutathione synthetase gene (GSH), glutathione reductase gene (GR) and glutathione peroxidase gene (GPX) in tomato leaves, but such increases were not observed in leaves exposed to CAR. In addition, GSTs, GR, peroxidase (POD) activities and most of GSH-dependent gene expression were induced by CHT in a concentration- and time-dependent manner. These results suggest that GSH-dependent pathway plays an important role in the CHT detoxification but not in the CAR detoxification in tomato leaves.