Abstract: Leaves of alfalfa varieties with various resistance to pea aphids(Acyrthosiphon pisum Harris) were used as tested material.The dynamics of chlorophyll,soluble protein,total phenolic contents and the activity of Polyphenol oxidase(PPO) were tested using a UV-visible spectrophotometer and catalase activity was tested by potassium permanganate to study the relationship between aphid stress and physiological activity.Results indicated that the activities of PPO in all varieties initially increased then declined when their leaves were pierced by sucking aphids.PPO activities of resistant variety(G5) were higher than that of susceptible variety(Hu) and low resistant varieties(G3,JH) before invasion by pea aphids,whereas PPO activities resistant variety(G5) decreased rapidly,then were lower than that of susceptible variety(Hu) after infection by pea aphids.Throughout the period of aphid attacks,total phenolic content and CAT activity of resistant variety(G5) were higher than that of susceptible variety(Hu) and low resistant varieties(G3,JH).The chlorophyll content of the susceptible variety(Hu) was higher than that of low resistant varieties(G3,JH),lower than that of resistant variety(G5).Soluble protein content of resistant variety(G5) and the susceptible variety(Hu) were lower than that of low resistant cultivars(G3,JH),except soluble protein content of G5 and Hu were higher than that of G3 on the third day after pea aphids invading.The chlorophyll and soluble protein contents and CAT activities displayed a decreasing trend in all varieties.Results indicated that the chlorophyll,soluble protein contents,and PPO did not have explicit correlation with the resistance of M.sativa to pea aphid,whereas total phenolic content and CAT have positive correlations.

Key words: Medicago sativa varieties, Acyrthosiphon pisum, Biochemical resistance mechanism, Chlorophyll, Soluble protein, Polyphenol oxidase, Catalase

摘要： 采用紫外分光光度法和高锰酸钾法测定了不同抗蚜性苜蓿(Medicago sativa L.)品种受豌豆蚜(Acyrthosiphon pisum Harris)为害胁迫后叶片内叶绿素(Chl)、可溶性蛋白、总酚含量及防御性酶多酚氧化酶(PPO)和过氧化氢酶(CAT)活性的动态变化,以期明确各项生理指标与抗虫性之间的关系。结果表明:在蚜虫刺吸诱导过程中,4个品种的PPO均呈先下降后上升的趋势,其中接蚜前抗虫品种甘农5号(G5)PPO活性高于感虫品种猎人河(Hu)和低抗品种甘农3号(G3)、金皇后(JH),接蚜后迅速下降,其活性低于感虫品种;抗虫品种甘农5号CAT活性和总酚含量始终高于低抗品种和感虫品种;感虫品种(Hu)Chl含量高于低抗品种(G3,JH),但低于抗虫品种(G5);感虫品种和抗虫品种的可溶性蛋白含量低于低抗品种(除第3 d高于G3);4个品种的CAT活性、Chl含量、可溶性蛋白含量均呈下降趋势。因此,苜蓿品种的Chl、可溶性蛋白、PPO与其对豌豆蚜抗性的相关性不明确,而总酚、CAT与抗蚜性呈正相关。

关键词: 苜蓿品种, 豌豆蚜, 生化抗性机制, 叶绿素, 可溶性蛋白, 多酚氧化酶, 过氧化氢酶