WRKY46 functions as a transcriptional repressor of ALMT1, regulating aluminum‐induced malate secretion in Arabidopsis. (5th November 2013)

• Record Type: Journal Article
• Authors: Ding, Zhong Jie; Yan, Jing Ying; Xu, Xiao Yan; Li, Gui Xin; Zheng, Shao Jian
• Is Part Of: Plant journal. Volume 76:Number 5(2013:Dec.)
• Page Start: 825
• Page End: 835
• Publication Date: 2013-11-05
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12337
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12337-abs-0001"> <title>Summary</title> <p>Aluminum (Al) toxicity is the major limiting factor for crop production on acid soils, but the transcriptional regulation of Al tolerance genes is largely unknown. Here, we found that the expression of a WRKY domain‐containing transcription factor <italic>WRKY46</italic> is inhibited by Al and expressed in root stele, whereas the expression of <italic>ALMT1</italic>, which encodes a malate efflux transporter, is induced by Al stress and spatially co‐localized with <italic>WRKY46</italic> in root stele, indicating the possible interaction between <italic>WRKY46</italic> and <italic>ALMT1</italic> in Arabidopsis. Mutation of <italic>WRKY46</italic> by T–DNA insertion leads to better root growth under Al stress, and lower root Al content compared with the wild‐type Col–0. The <italic>wrky46</italic> mutant shows increased root malate secretion, which is consistent with the higher <italic>ALMT1</italic> expression in the mutant. Transient expression analysis using truncated promoter of <italic>ALMT1</italic> showed that <italic>ALMT1</italic> expression can be inhibited by WRKY46 in tobacco leaves. The yeast one‐hybrid assay and ChIP‐qPCR analysis revealed that WRKY46 directly binds to <italic>ALMT1</italic> promoter through specific W–boxes. Taken together, we demonstrated that <italic>WRKY46</italic> is a negative regulator of <italic>ALMT1</italic>, mutation of WRKY46 leads to increased malate secretion and reduced Al accumulation in root apices, and thus confers higher Al resistance.</p> </abstract>