Transcription factor, also called sequence specific DNA binding factor, is a protein which can bind to specific DNA sequences, and then controlling the rate of transcription from DNA to messenger RNA. By binding to either enhan￣cer or promoter regions of DNA adjacent to the genes, transcription factors can control the transcription level of the adja￣cent gene either up or down regulated. In plants, transcription factors use a variety of mechanisms for the regulation of gene expression, when plants are in response to environmental stimuli, especially to biotic or abiotic stresses. WRKY transcription factors are conserved in evolutional history throughout the Plant Kingdom, which play essential roles in va￣rious physiological processes. Members of plant WRKY gene family are ancient transcription factors that function in plant growth and development and respond to biotic and abiotic stresses. Previous studies have demonstrated that WRKY tran￣scription factors play essential roles in various physiological processes, including senescence, root development, sugar signaling, and germination. Furthermore, WRKY transcription factors have been shown to be involved in responses to va￣rious biotic stresses caused by viruses, bacterial pathogens, fungi, abiotic stresses including drought, heat, cold, and so on, and some signaling substances such as salicylic acid ( SA )/benzothiadiazole, jasmonic acid, gibberellin and ABA. All members of this family contain at least one conserved DNA￣binding domain with a highly conserved WRKYGQK heptapeptide sequence. These conserved sequences have been designated as the WRKY domains, and func￣tion in W￣box DNA motif (C/T)TGAC(C/T) binding activation, to regulate stress￣response gene expression, which were induced by pathogen, wound external stimuli and signal molecule. Here, this present review concentrates on the re￣cent report about function study of WRKY transcription factors, including abiotic stresses ( cold,drought,salinity) and various biotic stresses ( viruses, bacterial pathogens, fungi) , intent to elucidate how these WRKY proteins regulate the plant defense and how they interact with each other will be hot topics for future studies.%转录因子是一类在生物生命活动过程中起到调控作用的重要因子,参与了各种信号转导和调控过程,可以直接或间接结合在顺式作用元件上,实现调控目标基因转录效率的抑制或增强,从而使植物在应对逆境胁迫下做出反应。 WRKY转录因子在大多数植物体内都有分布,是一类进化非常保守的转录因子家族,参与植物生长发育以及响应逆境胁迫的生理过程。众多研究表明,WRKY转录因子在植物中能够应答各种生物胁迫,如细菌、病毒和真菌等；多种非生物胁迫,包括高温、冷害、高光和高盐等；以及在各种植物激素,包括茉莉酸( JA)、水杨酸( SA)、脱落酸( ABA)和赤霉素( GA)等,在其信号传递途径中都起着重要作用。 WRKY转录因子家族蛋白至少含有一段60个氨基酸左右的高度保守序列,被称为WRKY结构域,其中WRKYGQK多肽序列是最为保守的,因此而得名。该转录因子的WRKY结构域能与目标基因启动子中的顺式作用元件W￣box( TTGAC序列)特异结合,从而调节目标基因的表达,其调控基因表达主要受病原菌、虫咬、机械损伤、外界胁迫压力和信号分子的诱导。该文介绍了植物WRKY转录因子在植物应对冷害、干旱、高盐等非生物胁迫与病菌、虫害等生物胁迫反应中的重要调控功能,并总结了WRKY转录因子在调控这些逆境胁迫反应过程中的主要生理机制。
展开▼
