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

野油菜黄单胞菌Xanthomonas campestris PV的AvrBs3蛋白。泡囊藻(XCV)通过III型分泌系统被注射到其寄主植物辣椒的细胞质中。AvrBs3转位到寄主的细胞核，结合并转录激活辣椒BS3抗性(R)基因的启动子，导致过敏反应(HR)。BS3编码一种结构上非典型的黄素单加氧酶，它与任何已知的植物R蛋白没有同源性。初步研究表明，转录因子AvrBs3和“HR Executer”BS3不仅在辣椒中具有功能，而且在模式植物拟南芥中也具有功能，这是对BS3介导的免疫反应进行遗传解剖的先决条件。为此，拟南芥将在雌激素诱导启动子的转录控制下，用含有BS3的报告结构物进行转化。突变筛选旨在发现Bs3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鉴定后，我们将分离相应的基因，并在分子水平上对其进行鉴定。长期目标是阐明已识别的基因在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.