3种不同类型口器的昆虫取食对菜豆叶片PPO和PAL活性的影响

Effects of feeding of insects with three types of mouthparts on the activities of polyphenols oxidase( PPO) and phenylalnine ammonialyase( PAL) in leaves of kidney bean plant

为研究不同口器昆虫取食对菜豆植株系统防御的影响,以斜纹夜蛾(Spodoptera litura)咀嚼取食、二斑叶螨(Tetranychus urticae)刺吸取食和西花蓟马(Frankliniella occidentalis)锉吸取食分别处理菜豆中部叶片6、24、48、72和96 h后,测定菜豆受处理的中部叶片及未处理的上部及下部位叶片多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)的活性。结果表明:危害方式、处理时间和叶片部位对菜豆叶片PPO和PAL活性有极显著影响(P<0.01),且三者间有极显著的交互作用。不同危害方式诱导后中部处理叶片的PPO活性均是在6 h明显升高(P<0.05),但随时间的延长PPO活性在不同处理下变化不同;中部叶片PAL活性在机械损伤处理48 h后才被显著激活,而斜纹夜蛾、二斑叶螨和西花蓟马取食后,PAL活性分别在6、6和24 h明显升高,且达到最大值,分别是对照的2.66、1.75和2.79倍;处理菜豆的上部和下部未受害叶片的PPO和PAL活性对虫害的响应明显比机械损伤迅速;二斑叶螨取食后PAL活性响应最快,上部和下部叶片均在6 h达到最大值,分别为对照的2.72和5.07倍。以上结果说明,害虫取食能引起菜豆植株产生系统防御反应,并且防御的时空效应与害虫的为害方式有关。

To clarify the effects of feeding-modes of different insects on systematic defenses in kidney bean plant, we examined the impacts of damages by tobacco cutworm Spodoptera litura （ chewing）, spider mite Tetranychus urticae （ piercing-sucking）, and western flower thrips Fran- kliniella occidentalis （rasping-sucking） after 6, 24, 48, and 96 h of feeding middle leaves on activities of polyphenols oxidase （PPO） and phenylalnine ammonialyase （PAL） in the damaged middle leaves and undamaged upper and lower leaves of kidney bean plant. The results showed that PAL and PPO activities were significantly influenced by treatment types, periods of time and leaf position （P〈0.01）, with significant interactions among the three factors. The activities of PPO in middle leaves increased significantly at 6 h in all different treatments （P〈0.05）, and changed in different patterns with time extension. The PAL activity in middle leaves was not sig- nificantly activated until 48 h after mechanical damage （CK）. The activities of PAL in middle leave fed by S. litura, T. urticae and F. occidentalis increased obviously at 6, 6 and 24 h, and reached the maximum, being 2.66, 1.75 and 2.79 times of the control, respectively. The respon- ses of the PAL and PPO in undamaged upper and lower leaves by herbivore feeding were fasterthan that by mechanical damage. T. urticae feeding caused the fastest changes of PAL activity. The activities of PAL in the upper and lower leaves by T. urticae feeding reached the maximum at 6 h, which were 2.72 and 5.07 times of the control, respectively. Our results indicated that her bivore feeding could induce the systematic defenses of kidney bean plant, with the effects of temporal and spatial defenses related to the types of pests.