Mutational sceens in Arabidopsis aimed at identifying genes that are required for functionality of the pepper Bs3 restistance gene

植物致病菌油菜黄单胞菌的AvrBs3蛋白。该病毒通过III型分泌系统注入宿主植物辣椒的细胞质中。avrbs3转运到宿主细胞核，结合并转录激活辣椒Bs3抗性(R)基因启动子，导致过敏反应（hypersensitive response， HR）。Bs3编码结构上不典型的黄素单加氧酶，与任何已知的植物蛋白都没有同源性。初步研究表明，转录因子AvrBs3和“HR执行子”Bs3不仅在辣椒中有功能，在模式植物拟南芥中也有功能，这是基因解剖Bs3介导的拟南芥免疫反应的先决条件。因此，拟南芥将在雌二醇诱导启动子的转录控制下转化含有Bs3的报告基因结构。突变体筛选的目的是发现b3蛋白执行细胞死亡反应所需的基因。在对观察到的拟南芥突变体进行初步表征后，我们将分离相应的基因并在分子水平上对其进行表征。长期目标是阐明已鉴定基因在bs3介导的免疫反应中的功能。

The AvrBs3 protein of the bacterial phytopathogen Xanthomonas campestris pv. vesicatoria (Xcv)is injected via the type III secretion system into the cytoplasm of its host plant pepper. AvrBs3translocates to the host’s nucleus, binds to and transcriptionally activates the promoter of thepepper Bs3 resistance (R) gene, resulting in a hypersensitive response (HR). Bs3 encodes astructurally atypical flavin monooxygenase that does not share homology with any known plantR protein. Preliminary work has shown that the transcription factor AvrBs3 and the “HR executer”Bs3 are functional not only in pepper but also in the model plant Arabidopsis, which is theprerequisite for genetic dissection of the Bs3-mediated immune reaction in Arabidopsis. To do soArabidopsis will be transformed with a reporter construct that contains Bs3 under transcriptionalcontrol of an estradiol inducible promoter. Mutant screens aim to uncover genes that the Bs3protein requires to execute a cell death reaction. After initial characterization of the observedArabidopsis mutants we will isolate the corresponding genes and characterize them at themolecular level. The long-term goal is to elucidate the function of the identified genes in the contextof the Bs3-mediated immune response.