关键词: 西瓜, 小西葫芦黄花叶病毒, 防御酶活性, 抗病性

Abstract:

To determine the relationship between variation of activities of defensive enzymes and resistance to zucchin yellow mosaic virus(ZYMV) of watermelon,the dynamic changes of activities of superoxide dismutase(SOD),peroxydase(POD),polyphenol oxidase(PPO),phenylalanine ammonialyase (PAL) and catalase (CAT) in different resistant watermelon cultivar leaves, which were infected by ZYMV via artificial rubbing leaves,were analyzed.The results showed that activities of SOD,POD,PPO,PAL and CAT in watermelon leaves were significantly higher than those of the uninoculated control,and the activity peaks of SOD,POD,CAT,PAL appeared in high resistant and resistant cultivar leaves at 4,4,4,2 days after inoculation,which were 2 days earlier than the susceptible cultivar.And during the peak period,the enzyme activities of high resistant cultivar were increased by 29.80%,63.44%,55.62%,31.63% respectively,and those of the resistant cultivar were increased by 23.72%,58.13%,43.98%,19.35% respectively compared to the control,which were higher than those of the susceptible cultivar(14.29%,50.42%,39.78%,15.91%).There was no significant regularity of the PPO activity increase and peaks among the different resistant and susceptible watermelon cultivars.In conclusion,the higher the defensive enzymes activities of SOD, POD, PAL, CAT, PPO, the stronger the resistance to ZYMV of watermelon cultivar, and the activity changes of SOD, POD, PAL and CAT were closely related to watermelon resistance to ZYMV.Therefore, the four defensive enzymes played an important role in resistant mechanism of watermelon to ZYMV.The enzyme activity peak emergence time and increase range could be taken as important physiological indexes for screening of watermelon cultivars’ resistance to ZYMV.

Key words: Watermelon, Zucchin yellow mosaic virus, Defensive enzyme activities, Disease resistance