Abstract:

Changes of protective enzymes and the content of H₂O₂ were studied after Alternaria brassicicola infection on two no-heading Chinese cabbage materials（Suzhouqing and Duanbaigeng）. Results showed that PPO activity, SOD activity and CAT activity were increased in both disease-resistant material and disease-susceptible material, and PPO activity, SOD activity in Suzhouqing was higher than that in Duanbaigeng after infection, while CAT activity was lower than that in Duanbaigeng. As to PAL activity it was increased in Suzhouqing but decreased in Duanbaigeng. POD activity and H₂O₂ content was increased in both Suzhouqing and Duanbaigeng after inoculation, and the content of H₂O₂ could be lowered quickly in disease-resistant line. Thus it could be considered that compared with disease-susceptible material, disease-resistant material was able to produce more PPO and PAL that may resist the infection of Alternaria brassicicola, and was able to produce more H₂O₂ in short time to promote antioxidant enzymes activities, which could maintain low ROS level and reduce the damage of ROS after innoculation.

Key words: non-heading Chinese cabbage, Alternaria brassicicola, protective enzymes, H2O2