Chen C, Chen Z
Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow 83844-3052, USA.
Plant Mol Biol. 2000 Jan;42(2):387-96. doi: 10.1023/a:1006399311615.
A pathogen- and salicylic acid (SA)-induced DNA-binding activity has been recently identified in tobacco that is related to a previously identified class of WRKY DNA-binding proteins. To identify members of the WRKY gene family associated with this DNA-binding activity, we have attempted to isolate those WRKY genes that are induced by pathogen infection. Using a domain-specific differential display procedure, we have isolated two tobacco WRKY genes, tWRKY3 and tWRKY4, that are rapidly induced in resistant tobacco plants after infection by tobacco mosaic virus (TMV). Both tWRK3 and tWRKY4 encode proteins with a single WRKY domain that contain the conserved WRKYGQK sequence. Unlike other isolated WRKY proteins that contain the Cys2His2 zinc motif, tWRKY3 and tWRKY4 appear to contain the Cys2HisCys zinc motif. Nonetheless, both tWRKY3 and tWRKY4 are capable of binding DNA molecules with the W-box (TTGAC) element recognized by other WRKY proteins. Expression of the tWRKY3 and tWRKY4 genes could be rapidly induced not only by TMV infection but also by SA or its biologically active analogues that are capable of inducing pathogenesis-related genes and enhanced resistance. Interestingly, induction of both genes by TMV infection was still observed in resistant tobacco plants expressing the bacterial salicylate hydroxylase gene (nahG), although the levels of induction appeared to be reduced. Identification of pathogen- and SA-induced genes encoding WRKY DNA-binding proteins should facilitate future studies on the regulation and functions of this novel group of DNA-binding proteins.
最近在烟草中发现了一种由病原体和水杨酸（SA）诱导的DNA结合活性，它与先前鉴定的一类WRKY DNA结合蛋白有关。为了鉴定与这种DNA结合活性相关的WRKY基因家族成员，我们试图分离那些由病原体感染诱导的WRKY基因。使用一种域特异性差异显示方法，我们分离出了两个烟草WRKY基因，tWRKY3和tWRKY4，它们在烟草花叶病毒（TMV）感染后在抗性烟草植株中被快速诱导。tWRK3和tWRKY4都编码具有单个WRKY结构域的蛋白质，该结构域包含保守的WRKYGQK序列。与其他含有Cys2His2锌基序的分离WRKY蛋白不同，tWRKY3和tWRKY4似乎含有Cys2HisCys锌基序。尽管如此，tWRKY3和tWRKY4都能够结合具有其他WRKY蛋白识别的W盒（TTGAC）元件的DNA分子。tWRKY3和tWRKY4基因的表达不仅可以被TMV感染快速诱导，还可以被SA或其能够诱导病程相关基因和增强抗性的生物活性类似物诱导。有趣的是，在表达细菌水杨酸羟化酶基因（nahG）的抗性烟草植株中，仍然观察到TMV感染对这两个基因的诱导，尽管诱导水平似乎有所降低。鉴定编码WRKY DNA结合蛋白的病原体和SA诱导基因应该有助于未来对这一新的DNA结合蛋白组的调控和功能的研究。
