植物应对病毒的免疫响应

The Plant Immune System in Response to Virus Infection

植物为应对外界病原体的侵扰,在进化过程中形成了一套多层次的免疫系统。对于植物应对真菌、细菌的免疫过程,前期建立了基于寄主与病原分子间相互作用的Z免疫模型。其中第一层次是由病原相关分子模式(PAMP)激发的免疫响应(PTI);另一层次是由效应子(Effector)激发的免疫响应(ETI)。植物在应对病毒的免疫响应中,第一层次是主动清除降解细胞内的病毒核酸,即通过一种高度保守的、序列特异的RNA沉默防御机制来实现;病毒攻克RNA沉默机制后,与应对真菌、细菌的免疫过程相似,植物进而启动基于R基因的免疫响应。另外,植物在免疫过程中还会通过激活一系列信号途径,使植物产生过敏反应或产生系统性抗性,从而抵抗病原体的进一步浸染。本文通过免疫系统分子模型,就近年来有关植物响应病毒的分子调控机制进行了综述。

Plants possess a multilayered defense response, known as plant innate immunity, in response to infection by a wide variety of pathogen. To elucidate events between the host and pathogen, a zigzag model is defined to uncover aspects common to different molecules interactions in host. In this model, the first phase is induced by the recognition of pathogen-associated molecular patterns(PAMP), which initiates PAMP triggered immunity(PTI). The next phase of plant immunity is triggered by the effectors(ETI). In the case of plant viruses,the primary plant defense is thought to be based mainly on RNA silencing, a conserved sequence-specific gene regulation system, that represses invasive virus nucleic acids. To counteract RNA silencing and establish robust infection in susceptible hosts, the virus deploy effector into the host cell. Plants have then evolved resistance(R) genes that mediate intracellular recognition of effector proteins, similar mechanisms with fungi and bacteria infection, which results in effector triggered immunity(ETI). In addition, plants also active differently signal pathway to induce hypersensitive and systemic acquired resistance responses, which together limit the virus to infected cells and impart resistance to the no-infected tissues. Here, we defined the immunity models especially and provided a summary and update of advances in plant immune responses to virus.