Salicylic Acid Suppresses Apical Hook Formation via NPR1-Mediated Repression of EIN3 and EIL1 in Arabidopsis

First author: Peixin Huang; Affiliations: Southern University of Science and Technology (南方科技大学): Shenzhen, China

Corresponding author: Hongwei Guo

Salicylic acid (SA) and ethylene (ET) are important phytohormones that regulate numerous plant growth, development, and stress response processes. Previous studies have suggested functional interplay of SA and ET in defense responses, but precisely how these two hormones coregulate plant growth and development processes remains unclear. Our present work reveals antagonism between SA and ET in apical hook formation, which ensures successful soil emergence of etiolated dicotyledonous seedlings. Exogenous SA inhibited ET-induced expression of HOOKLESS1 (HLS1) in Arabidopsis thaliana in a manner dependent on ETHYLENE INSENSITIVE3 (EIN3) and EIN3-LIKE1 (EIL1), the core transcription factors in the ET signaling pathway. SA-activated NONEXPRESSER OF PR GENES1 (NPR1) physically interacted with EIN3 and interfered with the binding of EIN3 to target gene promoters, including the HLS1 promoter. Transcriptomic analysis revealed that NPR1 and EIN3/EIL1 coordinately regulated subsets of genes that mediate plant growth and stress responses, suggesting that the interaction between NPR1 and EIN3/EIL1 is an important mechanism for integrating the SA and ET signaling pathways in multiple physiological processes. Taken together, our findings illuminate the molecular mechanism underlying SA regulation of apical hook formation as well as the antagonism between SA and ET in early seedling establishment and possibly other physiological processes.

水杨酸SA和乙烯ET都是非常重要的植物激素，其调控多个植物生长、发育和胁迫响应进程。先前的研究已经报道了SA和ET之间的功能性互作能够作用于植物的防御响应，但这两种植物激素如何精密配合，共调控植物的生长和发育进程还不清楚。本文中，作者的研究揭示了SA和ET在植物的顶钩形成过程中存在拮抗作用，而该过程对于确保土壤中黄化的双子叶植物幼苗能够成功出土至关重要。外源的SA会抑制由拟南芥中ET诱导的HLS1基因表达，该过程依赖于两个ET信号转导途径中核心转录因子EIN3和EIL1。SA激活的NPR1物理上与EIN3互作，并且能够干扰EIN3对于靶基因启动子的结合，其中就包括了HLS1基因的启动子。转录组学分析显示，NPR1和EIN3/EIL1协调调控介导植物生长和胁迫响应的基因子集，表明NPR1和EIN3/EIL1之间的相互作用是SA和ET信号通路作用于多个生理过程的重要机制。综上，本文的研究揭示了SA调控植物顶钩形成的分子基础，同时也揭示了SA与ET之间在早期植物幼苗发育过程中的拮抗作用，该作用可能也适用于其它的生理进程。

通讯：郭红卫 (http://ipf.sustech.edu.cn/?page_id=1&hash=c2f45f06677de09354d8d72f246fa65e#artical)

个人简介：1988-1992年，南开大学，学士；1992-1995年，北京大学，硕士；1996-2001年，美国加州大学洛杉矶分校，博士；2001-2005年，美国加州Salk Institute，博士后。

研究方向：植物激素信号转导；植物衰老与采后生物学；植物siRNA生物学。

doi: https://doi.org/10.1105/tpc.19.00658

Journal: Plant Cell

First Published: December 30, 2019