西瓜叶片防御酶活性变化与病毒病抗性的关系

Relationship between Variation of Leaf Defensive Enzyme Activities and Resistance of Watermelon Cultivar to Zucchin Yellow Mosaic Virus

为探明西瓜防御酶活性变化与病毒病抗性之间的关系,以高抗、抗、感3种不同抗性的西瓜品系为材料,采用人工摩擦接种小西葫芦黄花叶病毒(ZYMV),测定接种后西瓜幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、过氧化氢酶(CAT)活性的变化。结果表明,接种后3种不同抗性西瓜品系叶片SOD、POD、PAL、CAT、PPO活性均显著高于其对照(不接种ZYMV);高抗和抗性品系的叶片SOD、POD、CAT、PAL活性分别在接种后第4、4、4、2天达到峰值,均较感病品系提前2 d,且峰值期高抗品系酶活性较其对照增幅分别为29.80%、63.44%、55.62%、31.63%,抗性品系酶活性较其对照增幅分别为23.72%、58.13%、43.98%、19.35%,且均高于感病品系(14.29%、50.42%、39.78%、15.91%);叶片PPO活性增幅和峰值出现时间在3种不同抗感性品系间无明显规律。可见,SOD、POD、PAL、CAT、PPO活性越高,西瓜品系的抗ZYMV能力越强;SOD、POD、PAL、CAT活性变化与西瓜病毒病抗性密切相关,在抗病生理机制中起重要作用,这4种酶活性峰值出现的时间及增幅大小可作为西瓜ZYMV抗性筛选的重要生理指标。

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.