Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong.
Plant J. 2019 Jan;97(2):352-367. doi: 10.1111/tpj.14124. Epub 2018 Nov 12.
WRKY transcription factors (TFs) belong to a large family of regulatory proteins in plants that modulate many plant processes. Extensive studies have been conducted on WRKY-mediated defense response in Arabidopsis thaliana and several crop species. Here, we aimed to investigate the potential roles and contributions of WRKY TFs in improving the defense response in the resynthesized Arabidopsis allotetraploids (Arabidopsis suecica) derived from two related autotetraploid progenitors, Arabidopsis thaliana (At4) and Arabidopsis arenosa (Aa). Rapid and differential induction of WRKY18 and WRKY40 expression was evident in response to Pseudomonas syringae and salicylic acid (SA) treatments in the allotetraploids. Selected direct targets of the WRKYs and PR1 also showed altered induction kinetics in the allotetraploids. Cleaved amplified polymorphic sequence analysis further revealed the accumulation of preferential homoeologous alleles (AtWRKY18, AaWRKY40, and AtWRKY60) in the allotetraploids, suggesting the potential for altered protein-protein interaction networks in the hybrids. Indeed, results showed that the cis-interacting AtWRKY18/AtWRKY18 homodimer or trans-interacting AtWRKY18/AaWRKY40 heterodimer exists as the preferred dimer interaction. Moreover, differential affinities of WRKY18 and WRKY40 homo- and heterodimers toward the W-boxes in the WRKY60 promoter were observed. Transient and stable expression of the selected WRKYs in transgenic Arabidopsis further supported the idea that differential interactions lead to changes in PR1 induction and direct target expression under stress, respectively. Our data suggest that differential expression as well as differences in the strength of protein-protein and/or protein-DNA interactions among the WRKY homoeologs could lead to altered regulatory networks of defense genes, contributing to improved defense in allotetraploids.
WRKY 转录因子（TFs）属于植物中一类调节许多植物过程的调控蛋白大家族。已经在拟南芥和几种作物物种中进行了广泛的 WRKY 介导的防御反应研究。在这里，我们旨在研究 WRKY TF 在提高由两个相关的同源四倍体亲本拟南芥（At4）和拟南芥砂（Aa）衍生的再合成拟南芥异源四倍体中防御反应的潜在作用和贡献。WRKY18 和 WRKY40 的表达在对丁香假单胞菌和水杨酸（SA）处理的异源四倍体中迅速且有差异地诱导。WRKY 和 PR1 的选定直接靶标在异源四倍体中也表现出诱导动力学的改变。切割扩增多态性序列分析进一步揭示了偏爱同系等位基因（AtWRKY18、AaWRKY40 和 AtWRKY60）在异源四倍体中的积累，表明杂种中可能存在改变的蛋白质-蛋白质相互作用网络。事实上，结果表明，AtWRKY18/AtWRKY18 同源二聚体或 AtWRKY18/AaWRKY40 异源二聚体的顺式相互作用作为优选的二聚体相互作用存在。此外，还观察到 WRKY18 和 WRKY40 同源和异源二聚体对 WRKY60 启动子中 W 框的差异亲和力。所选 WRKYs 在转基因拟南芥中的瞬时和稳定表达进一步支持了这样一种观点，即差异相互作用导致在胁迫下 PR1 诱导和直接靶标表达的变化，分别。我们的数据表明，WRKY 同系物之间的差异表达以及蛋白质-蛋白质和/或蛋白质-DNA 相互作用的强度差异可能导致防御基因的调节网络发生改变，从而提高异源四倍体的防御能力。
