Niu Fangfang, Cui Xing, Yang Bo, Wang Rui, Zhao Peiyu, Zhao Xinjie, Zhang Hanfeng, Fan Xiaojiang, Li Ye, Deyholos Michael K, Jiang Yuan-Qing
National Key Laboratory of Crop Improvement for Stress Tolerance and Production, College of Life Science, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Department of Biology, University of British Columbia, Okanagan Campus, Kelowna, V1V 1V7, Canada.
Plant J. 2024 Jun;118(5):1652-1667. doi: 10.1111/tpj.16703. Epub 2024 Feb 28.
Potassium (K), being an essential macronutrient in plants, plays a central role in many aspects. Root growth is highly plastic and is affected by many different abiotic stresses including nutrient deficiency. The Shaker-type K channel Arabidopsis (Arabidopsis thaliana) K Transporter 1 (AKT1) is responsible for K uptake under both low and high external K conditions. However, the upstream transcription factor of AKT1 is not clear. Here, we demonstrated that the WRKY6 transcription factor modulates root growth to low potassium (LK) stress in Arabidopsis. WRKY6 showed a quick response to LK stress and also to many other abiotic stress treatments. The two wrky6 T-DNA insertion mutants were highly sensitive to LK treatment, whose primary root lengths were much shorter, less biomass and lower K content in roots than those of wild-type plants, while WRKY6-overexpression lines showed opposite phenotypes. A further investigation showed that WRKY6 regulated the expression of the AKT1 gene via directly binding to the W-box elements in its promoter through EMSA and ChIP-qPCR assays. A dual luciferase reporter analysis further demonstrated that WRKY6 enhanced the transcription of AKT1. Genetic analysis further revealed that the overexpression of AKT1 greatly rescued the short root phenotype of the wrky6 mutant under LK stress, suggesting AKT1 is epistatic to WRKY6 in the control of LK response. Further transcriptome profiling suggested that WRKY6 modulates LK response through a complex regulatory network. Thus, this study unveils a transcription factor that modulates root growth under potassium deficiency conditions by affecting the potassium channel gene AKT1 expression.
钾（K）作为植物必需的大量营养素，在许多方面发挥着核心作用。根的生长具有高度可塑性，并且受到包括营养缺乏在内的许多不同非生物胁迫的影响。拟南芥（Arabidopsis thaliana）中的振荡型钾通道钾转运体1（AKT1）负责在外部钾含量低和高的条件下吸收钾。然而，AKT1的上游转录因子尚不清楚。在这里，我们证明了WRKY6转录因子调节拟南芥对低钾（LK）胁迫的根生长。WRKY6对LK胁迫以及许多其他非生物胁迫处理表现出快速响应。两个wrky6 T-DNA插入突变体对LK处理高度敏感，其主根长度比野生型植物短得多，生物量少且根中的钾含量低，而WRKY6过表达系表现出相反的表型。进一步的研究表明，WRKY6通过电泳迁移率变动分析（EMSA）和染色质免疫沉淀定量PCR（ChIP-qPCR）测定法直接结合其启动子中的W-box元件来调节AKT1基因的表达。双荧光素酶报告基因分析进一步证明WRKY6增强了AKT1的转录。遗传分析进一步揭示，在LK胁迫下，AKT1的过表达极大地挽救了wrky6突变体的短根表型，表明在LK响应的控制中AKT1对WRKY6上位。进一步的转录组分析表明，WRKY6通过复杂的调控网络调节LK响应。因此，本研究揭示了一种转录因子，其通过影响钾通道基因AKT1的表达来调节缺钾条件下的根生长。
