外源水杨酸对黄瓜幼苗灰霉病防御酶活性的影响

Effect of exogenous salicylic acid on the activity of defense enzymes against gray mold in cucumber seedlings

为研究水杨酸(SA)对感染灰霉病黄瓜幼苗防御酶活性的影响,采用叶面喷施外源水杨酸(SA),测定SA对感染灰霉病黄瓜幼苗叶片中多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、过氧化氢酶(CAT)、过氧化物酶(POD)和过氧化物歧化酶(SOD)5种防御酶活性的影响。结果表明:不同浓度SA对黄瓜幼苗抗灰霉病均有作用,能显著降低黄瓜幼苗的病情指数,其中以150 mg·L^(-1)的SA处理后的相对防效最高。叶面喷施150 mg·L^(-1)的SA后,随感染天数的增加PPO、PAL、CAT、POD、SOD 5种防御酶的活性均呈现出先上升后下降趋势,感染期间经SA处理后的5种防御酶的活性均高于未处理,其中PAL活性持续性较好。外源水杨酸能通过促进防御酶活性提高黄瓜幼苗抵抗灰霉病的伤害,浓度为150 mg·L^(-1)的SA处理抵抗作用最好。

To investigate the effects of salicylic acid(SA)on the activity of defense enzymes in cucumber seedlings infected with gray mold,exogenous salicylic acid(SA)was sprayed on the leaves of cucumber seedlings infected with gray mold to determine the effects of SA on the activities of five defense enzymes,namely polyphenol oxidase(PPO),phenylalanine ammonia lyase(PAL),catalase(CAT),peroxidase(POD)and peroxidase dismutase(SOD),in the leaves of cucumber seedlings infected with gray mold.The results showed that different concentrations of SA had effects on the resistance of cucumber seedlings to gray mold,and could significantly reduce the disease index of cucumber seedlings,among which 150 mg·L^(-1)SA had the highest relative control effect.After spraying 150 mg·L^(-1)SA,the activities of PPO,PAL,CAT,POD,and SOD showed a trend of first increase and then decrease with the increase of infection days.During the infection period,the activities of the five defense enzymes treated with SA were higher than those without treatment,and PAL activity was better sustained.Exogenous salicylic acid can enhance the resistance of cucumber seedlings to gray mold damage by promoting defense enzyme activity,and the SA treatment with the concentration of 150 mg·L^(-1)has the best resistance.