番茄RBOH和MAPK基因在番茄防御害虫中的作用及机制

The plant early signaling RBOH (respiratory burst oxidase homologue) and MAPKs (mitogen-activated protein kinases) are central players in plant responses to abiotic and biotic stresses. In contrast, relatively little is known about their role in plant defense against pests. In this study, virus induced gene silencing technique will be used to examine the function and mechanism of RBOH and MAPKs in tomato defense against whitefly and cotton bollworm. First, the preference and performance of whitefly and cotton bollworm on tomato with silenced RBOH and MAPK will be examined. Then, to find the correlation between RBOH, MAPKs and reactive oxygen species (ROS), jasmonic acid (JA) and salicylic acid (SA) signaling, this study will monitor the pest-induced ROS, JA and SA signaling in control and RBOH, MAPK silenced tomato. Furthermore, to confirm the importance of JA and SA signaling in RBOH- and MAPKs-mediated tomato resistance to pests, methyl jasmonate and SA will be applied on tomato, and its effects on pests’ preference and performance will also be examined. This research intend to decipher the function and mechanism of RBOH and MAPKs in tomato resistance to pests with piercing-sucking and chewing mouthparts, which will provide more information about early signaling in plant defense against pests.

呼吸爆发氧化酶（RBOH）和丝裂原活化蛋白激酶（MAPKs）在植物应答外界胁迫信号传导中发挥重大作用，而这两类信号在植物防御害虫中的作用和机制仍不十分清楚。本项目采用病毒诱导基因沉默技术，研究番茄RBOH和MAPK基因在番茄防御烟粉虱和棉铃虫中的作用和机制。首先，测定沉默番茄RBOH和MAPK基因对烟粉虱和棉铃虫的寄主偏好和生长发育的影响，以明确这些基因在番茄抗虫中的作用。然后，检测沉默RBOH和MAPK基因对害虫诱导的番茄活性氧、茉莉酸和水杨酸信号途径以及番茄转录组的影响，以明确RBOH和MAPK基因介导的抗虫性和植物其他信号途径间的关联性。进而，施加茉莉酸甲酯和水杨酸于基因沉默的番茄植株，检测番茄抗虫性变化，明确茉莉酸和水杨酸在RBOH和MAPK基因介导的抗虫性中的作用。本项目通过研究番茄RBOH和MAPK基因在番茄防御害虫中的作用和机制，以期进一步揭示植物防御害虫的早期信号传导过程。

呼吸爆发氧化酶（respiratory burst oxidase homologue，RBOH）和丝裂原活化蛋白激酶（mitogen-activated protein kinases，MAPKs）在植物应答外界胁迫信号传导中发挥重大作用，而这两类信号途径在植物防御害虫中的作用和机制仍不十分清楚。本项目采用病毒诱导基因沉默技术，研究番茄RBOH和MAPK基因在番茄防御烟粉虱和棉铃虫中的作用和机制。首先，测定了烟粉虱和棉铃虫危害番茄后，对番茄RBOH和MAPK基因表达的影响，以明确这些基因在番茄抗虫中的变化。尽管棉铃虫和烟粉虱取食番茄叶片分别引起茉莉酸和水杨酸信号基因，但二者危害均未引起RBOH和MAPK家族基因的显著变化。烟粉虱危害番茄6天后显著增加叶片中氨基酸含量，以利于自身生长发育。然而，外源施加水杨酸并不会引起叶片氨基酸含量变化，说明烟粉虱引起的氨基酸变化并不完全依赖水杨酸信号途径。沉默番茄MAPK1/2导致番茄MAPK1下调57.3%，MAPK2下调47.1%；沉默MAPK3，导致番茄MAPK3下调71.7%。意外的是，MAPKs沉默反而导致番茄主要抗虫物质蛋白酶抑制剂II（PI-II）上升，但是棉铃虫取食1天后，对照番茄中PI-II比MAPKs沉默植株高约1.9倍，说明MAPKs在番茄启动PI-II中起到一定作用。棉铃虫在MAPK1/2沉默番茄上取食10天，体重比在对照植物上增加30.8%，而在MAPK3上的棉铃虫比对照体重多20.7%，但统计差异不显著。本项目发现烟粉虱不仅诱导水杨酸信号途径来抑制防御信号茉莉酸，而且可以增加番茄叶片中营养氨基酸含量；证实了植物早期信号MAPK在番茄防御棉铃虫中起到一定作用。