Zhou J, Tang X, Martin G B
Department of Agronomy, Purdue University, West Lafayette, IN 47907-1150, USA.
EMBO J. 1997 Jun 2;16(11):3207-18. doi: 10.1093/emboj/16.11.3207.
In tomato, the Pto kinase confers resistance to bacterial speck disease by recognizing the expression of a corresponding avirulence gene, avrPto, in the pathogen Pseudomonas syringae pv. tomato. Using the yeast two-hybrid system, we have identified three genes, Pti4, Pti5 and Pti6, that encode proteins that physically interact with the Pto kinase. Pti4/5/6 each encode a protein with characteristics that are typical of transcription factors and are similar to the tobacco ethylene-responsive element-binding proteins (EREBPs). Using a gel mobility-shift assay, we demonstrate that, similarly to EREBPs, Pti4/5/6 specifically recognize and bind to a DNA sequence that is present in the promoter region of a large number of genes encoding 'pathogenesis-related' (PR) proteins. Expression of several PR genes and a tobacco EREBP gene is specifically enhanced upon Pto-avrPto recognition in tobacco. These observations establish a direct connection between a disease resistance gene and the specific activation of plant defense genes.
在番茄中，Pto激酶通过识别病原菌丁香假单胞菌番茄致病变种（Pseudomonas syringae pv. tomato）中相应无毒基因avrPto的表达，赋予对细菌性斑点病的抗性。利用酵母双杂交系统，我们鉴定出三个基因Pti4、Pti5和Pti6，它们编码的蛋白质可与Pto激酶发生物理相互作用。Pti4/5/6各自编码一种具有转录因子典型特征的蛋白质，且与烟草乙烯应答元件结合蛋白（EREBPs）相似。通过凝胶迁移率变动分析，我们证明，与EREBPs类似，Pti4/5/6能特异性识别并结合大量编码“病程相关”（PR）蛋白的基因启动子区域中存在的DNA序列。在烟草中，Pto-avrPto识别后，几个PR基因和一个烟草EREBPs基因的表达会特异性增强。这些观察结果建立了抗病基因与植物防御基因特异性激活之间的直接联系。
