Abstract: It is necessary to study the relationship between aphid stress and oxidases in different alfalfa varieties for breeding of resistant alfalfa varieties and sustainable control of aphids.The changes in the activity of superoxide dismutase(SOD),peroxidase(POD),and polyphenol doxidase(PPO) were studied in seedling leaves of three alfalfa varieties,HA-3(High aphid resistance),Gannong No.3(aphid resistance),and Hunter River(low aphid resistance),infested by Therioaphis trifolii Monell through the artificial inoculation in lab.The results show that the activities of SOD,POD,and PPO in seedling leaves of three alfalfa varieties increased significantly along with the increasing of aphid densities.The changes in the activity of SOD,POD,and PPO of alfalfa seedling leaves after infestation by T.trifolii were significantly different among three alfalfa varieties.The SOD activities in seedling leaves of HA-3 and Gannong No.3 after infestation were higher than that of Hunter River,but the activities of POD and PPO were highest in HA-3,lowest in Hunter River,and middle in Gannong No.3.The differences of protective enzyme activities in three different aphids resistant alfalfa varieties were consistent with their resistant performances in the field.

Key words: Therioaphis trifolii Monell, Alfalfa seedling, Protective enzyme

摘要： 采用室内人工接虫的方法,研究HA-3(高抗)、甘农三号(中抗)和Hunter River(低抗)3种不同抗蚜苜蓿品种受苜蓿斑蚜(Therioaphis trifolii Monell)为害幼苗初期植株叶片SOD、POD、PPO等酶活性的变化。结果表明:苜蓿斑蚜为害后,3个苜蓿品种的SOD、POD、PPO的活性都显著上升,且随着虫口密度的增加而增强;苜蓿品种之间的SOD、POD、PPO活性变化存在显著差异;虽然HA-3苜蓿正常植株的SOD活性较高,但由于甘农三号苜蓿受蚜虫胁迫后SOD活性增长量大,使蚜虫胁迫植株的SOD活性与HA-3苜蓿没有显著差异;POD和PPO的活性在3个苜蓿品种正常植株之间没有显著差异,受蚜虫胁迫后,HA-3苜蓿的POD和PPO活性较高,甘农三号苜蓿次之,Hunter River苜蓿较低;3个苜蓿品种SOD、POD、PPO活性变化的差异,基本反映了其田间抗蚜性的差异水平。此研究对苜蓿抗蚜品种的选育及对蚜虫的持续控制具有重要意义。

关键词: 苜蓿斑蚜, 苜蓿幼苗, 保护酶