Molecular cloning and characterization of a novel WRKY gene from Brassica chinensis

A new WRKY gene was cloned from Brassica chinensis by rapid amplification of cDNA ends (RACE). The full-length cDNA of BcWRKY was 1175 bp long and contained a 924 bp open reading frame (ORF) encoding a putative W-box-binding protein of 308 amino acids. The predicted BcWRKY protein was found to have a potential bipartite nuclear localization sequence (NLS-BP) in its N-terminal region followed by a WRKY DNA-binding domain. Bioinformatic analysis revealed that BcWRKY resembled other WRKY domain-containing proteins from Arabidopsis (AtWRKY18), tobacco (WIZZ), parsley (PcWRKY4) and wild oat (ABF2). Expression of the BcWRKY gene could be induced by salicylic acid (SA), and influenced by Pseudomonas syringae pv. tomato strain DC3000 infection and wounding treatment. Our study implies that BcWRKY might have similar functions possessed by other WRKY genes such as inducing the expression of some defense-related genes and increasing plant's disease resistance ability.     

辣椒CaWRKY14转录因子的生物学特性研究

WRKY转录因子是植物响应病原菌胁迫最重要的转录因子之一,且参与抗病反应及信号传导通路的调控。为研究辣椒WRKY基因的生物学特征,以辣椒高抗疫病材料CM334为试材,克隆获得响应疫霉菌诱导的转录因子CaWRKY14。生物信息学分析表明,该基因DNA全长2 530 bp,cDNA全长1 662 bp,含有5个内含子,编码553个氨基酸,含有1个WRKY保守结构域,属于Group Ⅱ(b)。实时荧光定量表达分析表明,CaWRKY14不仅受ABA和疫霉菌胁迫诱导表达,且表达量分别在12 h和24 h时达到峰值,分别是对照的8.54和8.04倍,同时也受高盐、热激和干旱胁迫诱导。利用VIGS技术对CaWRKY14转录因子进行沉默后发现,抗病材料CM334接种疫霉菌后趋于发病。研究表明,CaWRKY14基因在辣椒响应疫霉菌胁迫进程中可能发挥着重要作用。     

PKS5, a SNF1-related kinase, interacts with and phosphorylates NPR1,and modulates expression of WRKY38 and WRKY62

NPR1 (Nonexpressor of Pathogenesis-Related gene 1) is a major co-activator of plant defense. Phosphorylations of NPR 1 play important roles in fine-tuning its activity, however a kinase corresponding to such modification remains uncharacterized. Here, we report that NPR1 interacts with PKS5 (SOS2-like Protein Kinase 5). The AKR (AnK yrin Repeats) motif of NPR1 is required for this interaction.PKS5 phosphorylates NPR1 at the C-temminal region. Expression of PKS5 is induced quickly by Pseudomonas syringae pv. tomato DC3000. Expression level of two NPR1 target genes, WRKY38 and WRKY62, is reduced and/or delayed in pks5 mutants. Moreover, the expression of WRKY38 and WRKY62 displays a similar pattern in npr1-1pks5-1 double mutant comparing to that in npr1-1. Our results suggest that PKS5 functions at the upstream of NPR1 and might mediate expression of WRKY38 and WRKY62 possibly by interacting with and phosphorylating NPR1.