| Isoproturon is a herbicide belonging to the phenylurea family and widely used to kill weeds in crop production. Recently, the over-use of isoproturon has led to its accumulation in ecosystems, thus bringing environmental risks to crop contamination and toxicity. Salicylic acid (SA) is one of components in plant resistant signaling pathways and regulates diverse physiological responses to biotic and environmental stresses.In this paper, to understand the role of SA in regulating wheat growth and oxidative stress to isoproturon, we carried out an initial experiment with isoproturon. The results revealed that isoproturon inhibited the growth and chlorophyll content of wheat plants and increased the concentrations of thiobarbituric acid reactive substances (TBARS) in shoots and roots of wheat plants. A preliminary experiment with SA at0,5,10,20and30mg L"1was performed to determine the point where SA displayed the maximal effect. Plants exposed to4mg·kg-1isoproturon showed growth stunt and oxidative damage. Thus, the5mg L"1SA and4mg kg-1Isoproturon were used for the following experiments.We investigated the role of SA in alleviating isoproturon-induced toxicity in wheat. Plants exposed to4mg kg-1isoproturon showed growth stunt and oxidative damage, but concomitant treatment with5mg L"1SA was able to attenuate the toxic effect. Isoproturon in soils was readily accumulated by wheat, but such accumulation can be blocked significantly by SA application. Treatment with SA decreased the abundance of O2-and H2O2as well as activities of antioxidant enzymes, and increased activities of catalase in isoproturon-induced plants. The enzyme activities were confirmed by the native polyacrylamide gel electrophoresis (PAGE). Further, a qRT-PCR-based assay was performed to show that several transcripts coding antioxidant enzymes were increased with isoproturon but decreased by SA. These results indicate that exogenous SA is able to improve the wheat tolerance to isoproturon toxicity. |
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