Expression Profile of Glutathione-S-Transferase Gene Family in Response to Cu(OH)2 Nanopesticide in Maize

Abstract Glutathione-S-transferases (GSTs) are a large family of genes that play a major role in detoxifying pesticides and tolerance to abiotic stress in plants. Copper hydroxide nanopesticides [Cu(OH) 2 NP] are nanostructures with two to three dimensions between 1-200 nm widely used in modern agriculture recently. There are very few studies on the eco-toxicological effects, behavior, and fate of these nanopesticides. In this study, one-week-old maize seedlings grown in a hydroponic medium were exposed to 10 mg/L Cu(OH) 2 NP for 7 d, and root-shoot length, ASA and GSH content, GST enzyme activity, and expression of all GST genes were examined. Besides, maize seedlings were exposed to 100 µM CuSO 4 for 7 d to evaluate the effect of copper ions. Results showed that both Cu(OH) 2 NP and CuSO 4 reduced root and shoot length. GST activity increased significantly after Cu(OH) 2 NP exposure. Foliar application of Cu(OH) 2 NP or CuSO 4 led to an accumu1ation of Cu in roots and shoots, and increased contents of GSH, GSSG, and DHA, but they reduced ASA level. Exposure to Cu(OH) 2 NP induced remarkable changes in the expression levels of GST genes in shoots and roots of maize seedlings; while 14 GST genes were up-regulated in shoots and 13 in roots, 7 GST genes were down-regulated in shoots and 8 in roots. The expression level of 17 genes in shoots and roots did not change. A similar trend for GST genes was also observed in CuSO 4 -treated seedlings. This indicated that most of the changes in GST gene expression were due to the released copper ions.