Exogenous 24-epibrassinolide regulates antioxidant and pesticide detoxification systems in grapevine after chlorothalonil treatment

The influence of 24-epibrassinolide (EBR) on the regulation of antioxidant and pesticide detoxification systems in grape seedlings (Vitis vinifera L.) was investigated. The grapevine leaves were pretreated with different concentrations of EBR (0.10, 0.21 and 0.42 mu M) before spraying with chlorothalonil (CHT) (600 times diluent). Compared with the control, CHT treatment showed an adverse effect on osmoregulation substances (soluble protein and free proline) and increased the content of malondialdehyde (MDA), activities of antioxidant enzymes and detoxification enzymes as well as the content of some non-enzymatic antioxidants. Compared to the CHT treatment alone, application of three concentrations of EBR resulted in an overall enhancement of these enzyme activities, soluble protein and free proline contents and reduction in MDA content. In addition, the expression of some key genes involved in CHT degradation including glutathione synthetase (GSH), glutathione S-transferase (GST), glutathione reductase (GR), P450 monooxygenase (P450) and MRP-type transporter (MRP) was analyzed. The transcriptional level of these genes increased in response to CHT treatment with the exception of GSH. EBR treatment of 0.10 mu M could effectively promote expression of most genes and accelerate CHT degradation by 29 % as compared to only CHT treatment in grapevine leaves.