Responses of Detoxification Enzymes and Genes to Nicosulfuron Stress in Two Genotypes of Sweet Corn Differing in Nicosulfuron Tolerance

Abstract

Nicosulfuron, a sulfonylurea herbicide is registered for use on field, controns many annual and perennial grass weeds. The accumulation of nicosulfuron will increase toxicity and induce unfavorable oxidative stress in plants. Acetolactate synthase (ALS, EC 2.2.1.6) and glutathione transferases (GSTs, E. C.2.5.1.18), which participate in detoxification of xenobiotics and limit oxidative damages of cellular macromolecules, are important groups of cytoprotective enzymes. This study aims to investigate the toxic effect of nicosulfuron on the detoxification enzyme activities and gene expressions in maize seedling. Specifically, Nicosulfuron-tolerant sweet inbred line ‘JP233’ and nicosulfuron-sensitive sweet inbred line ‘Z2H4’ are subjected to 80mg kg–1 nicosulfuron treatment when the fourth leaves are fully developed, and the resulting effects are compared to those processed by water. After nicosulfuron treatment, it is found that ALS and GST enzymes activities of Z2H4 are significantly lower than those of JP233. Compared to Z2H4, nicosulfuron treatment increases the expression levels of GST1, ALS1 and ALS2 genes in JP233. These results suggest that the increased transcription level of these detoxifying enzymes might play a vital role in reducing the toxicity of nicosulfuron and the oxidative stress induced by nicosulfuron in maize seedlings. The research will improve our understanding of the function of maize detoxification enzymes and genes in herbicide metabolism.