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

Abstract

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 CuSO4 for 7 d to evaluate the effect of copper ions. Results showed that both Cu(OH)2 NP and CuSO4 reduced root and shoot length. GST activity increased significantly after Cu(OH)2 NP exposure. Foliar application of Cu(OH)2 NP or CuSO4 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 CuSO4-treated seedlings. This indicated that most of the changes in GST gene expression were due to the released copper ions.