J. Agric. Food Chem., Article ASAP DOI: 10.1021/jf901915a
Brassinosteroids Promote Metabolism of Pesticides in Cucumber
Xiao Jian Xia?, Yun Zhang?, Jing Xue Wu?, Ji Tao Wang?, Yan Hong Zhou?, Kai Shi?, Yun Long Yu§ and Jing Quan Yu*??
Department of Horticulture, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, China
Department of Plant Protection, Zhejiang University, Hangzhou 310029, China
Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Agricultural Ministry of China, Hangzhou 310029, China
Brassinosteroids (BRs) are known to protect crops from the toxicity of herbicides, fungicides and insecticides. It is shown here that application of 24-epibrassinolide (EBR) accelerated metabolism of various pesticides and consequently reduced their residual levels in cucumber (Cucumis sativus L). Chlorpyrifos, a widely used insecticide, caused significant reductions of net photosynthetic rate (Pn) and quantum yield of PSII (ΦPSII) in cucumber leaves. EBR pretreatment alleviated the declines of Pn and ΦPSII caused by chlorpyrifos application, and this effect of EBR was associated with reductions of chlorpyrifos residues. To understand how EBR promotes chlorpyrifos metabolism, the effects of EBR on activity and expression of enzymes involved in pesticide metabolism were analyzed. EBR had a positive effect on the activation of glutathione S-transferase (GST), peroxidase (POD), and glutathione reductase (GR) after treatment with chlorpyrifos, although the effect on GR was attenuated at later time points when plants were treated with 1 mM chlorpyrifos. In addition, EBR enhanced the expression of P450 and MRP, which encode P450 monooxygenase and ABC-type transporter, respectively. However, the expression of GST was consistently lower than that of plants treated with only chlorpyrifos. Importantly, the stimulatory effect of EBR on pesticide metabolism was also observed for cypermethrin, chlorothalonil, and carbendazim, which was attributed to the enhanced activity and genes involved in pesticide metabolism. The results suggest that BRs may be promising, environmentally friendly, natural substances suitable for wide application to reduce the risks of human and environment exposure to pesticides.
Jing Quan Yu及其同事指出，杀虫剂对于为全世界不断增长的人口提供可持续的食品生产具有关键作用。全世界的农民每年使用250万吨杀虫剂。科学家一直在寻找让粮食作物收获后的杀虫剂残留最小的新方法——然而几乎没有成功。此前的研究提示，称为油菜素内酯（BRs）的植物激素可能成为这个问题的答案。