Differential regulation and interaction of homoeologous WRKY18 and WRKY40 in Arabidopsis allotetraploids and biotic stress responses

First author: Jayami K. Abeysinghe; Affiliations: Hong Kong Baptist University (香港浸会大学): Hong Kong, China

Corresponding author: Danny W.‐K. Ng

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 异源四倍体 (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 (丁香假单胞菌) and salicylic acid (SA) treatments in the allotetraploids. Selected direct targets of the WRKYs and PR1 also showed altered induction kinetics (动力学) in the allotetraploids. Cleaved amplified polymorphic sequence (酶切扩增多态性序列) analysis further revealed the accumulation of preferential homoeologous alleles (AtWRKY18, AaWRKY40, and AtWRKY60) in the allotetraploids, suggesting the potential for altered protein-protein interaction networksin 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 (亲近) of WRKY18 and WRKY40 homo‐ and heterodimers toward the W‐oxes 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转录因子属于植物中一大类调控因子，能够调控植物许多的生物学进程。对于拟南芥和一些作物中由WRKY介导的防御响应已经有了很多的研究。本文，作者研究了源自两个同源四倍体亲本：Arabidopsis thaliana和Arabidopsis arenosa形成的异源四倍体拟南芥Arabidopsis suecica中WRKY转录因子提升植株防御抗性的功能。在异源四倍体拟南芥中，WRKY18和WRKY40基因能够快速响应于丁香假单胞菌和水杨酸SA的处理发生表达量上的变化。异源四倍体拟南芥中WRKY的靶基因及PR1基因的分析同样显示了诱导动力学的改变。酶切扩增多态性序列CAPS分析进一步揭示了异源四倍体拟南芥中AtWRKY18、AaWRKY40和AaWRKY60同源等位基因的优先积累，说明在该杂种中蛋白-蛋白互作网络的改变。实际上，研究结果确实发现顺式互作AtWRKY18/AtWRKY18同型二聚体或反式互作AtWRKY18/AaWRKY40异型二聚体作为比较优先的二聚物互作方式。此外，作者还发现WRKY18和WRKY40同型或异型二聚物对于WRKY60基因启动子区W-boxes结合的亲和力有所差异。WRKY的转基因拟南芥植株进一步说明了不同的互作方式导致了胁迫条件下PR1诱导的改变和靶基因表达的改变。本文的研究揭示了WRKY基因的差异表达与蛋白-蛋白或蛋白-DNA互作强度上的差异一样能够改变抗性基因的调控网络，以作用于异源四倍体拟南芥的抗性能力提升。

通讯：NG Danny Wang Kit  (https://www.sls.cuhk.edu.hk/index.php/faculty-and-staff/teaching-staff/99-sls/faculty-and-staff/teaching-staff/579-professor-ng-danny-wang-kit)

个人简介：1998年，香港浸会大学，应用生物学学士；2001年，香港中文大学，生物学硕士；2005年，美国德州农工大学，生物学博士。

研究方向：表观遗传学与基因调控；植物抗病防御；多倍体与杂种优势；作物生物技术。

doi: https://doi.org/10.1111/tpj.14124

Journal: the plant journal

First Published: 11 October, 2018

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