Study on resistance of cabbage seedlings to black rot induced by coronatine treatment and its biochemical and physiological mechanism

The resistance effect and physiological mechanism of anti-black rot induced by coronatine (COR) in cabbage seedlings were studied by foliar application of COR and inoculation of black rot bacteria (Xanthomona scampestris pv. campestris).Susceptible cultivar cabbage (Brassica oleracea L.)Qing Feng was used as the seedling material.The results showed that COR induced black rot resistant in cabbage seedlings at the tested concentration of 0.01, 0.1 and 1.0 mg/L. The treatment of COR at 1.0 mg/L showed the best inductive effect,with the disease index as 38.2 and induced resistance rate as 43.7%.Comparing with that of the control,the catalase (CAT) activity and superoxide anion (O2-) generation rate increased significantly in leaf,but the superoxide dismutase (SOD) activity and malondialdehyde (MDA) were obviously decreased as the COR concentration increased. In summary,COR could induce black rot resistance in cabbage seedlings,which might be related with the variation of antioxidant enzyme activity,O2- generation rate and MDA content that induced by COR.