ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Abiotic Stress
BnALMT7-A4 Encodes an Aluminium-Activated Malate Transporter That Enhances Aluminium Tolerance in both Brassica napus L. and Arabidopsis thaliana
Provisionally accepted
- 1Southwest University, Chongqing, China
- 2University of Birmingham, Birmingham, United Kingdom
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Aluminum (Al³⁺) toxicity in acidic soils is a major constraint on agricultural productivity, with ALUMINIUM-ACTIVATED MALATE TRANSPORTER (ALMT) family genes mitigating Al³⁺ toxicity by secreting malate to chelate Al³⁺ and improve phosphate utilization. This study investigated the function of BnALMT7, a homolog of the Al-tolerant BnALMT1 in rapeseed (Brassica napus). Through qRT-PCR, promoter activity assays, and protein interaction analyses, BnALMT7-A4 and BnALMT7-C4 were identified as transmembrane proteins. BnALMT7-A4, highly homologous to Arabidopsis AtALMT7, localized to the plasma membrane and formed homodimers. Both genes were significantly induced by Al³⁺ in roots, with the BnALMT7-A4 promoter specifically active in the root vasculature. Overexpression of BnALMT7-A4 in transgenic Arabidopsis and rapeseed hairy roots enhanced root growth and reduced Al³⁺ accumulation in root tips under Al stress. Transcriptomic analysis revealed that BnALMT7-A4 overexpression upregulated oxidative stress-responsive genes (e.g., PER72, CML41) and downregulated detoxification-related genes (e.g., CYP81D11), reshaping the stress response network. In this study, we engineered Arabidopsis and Brassica overexpressing BnALMT7-A4 to generate Al-tolerant plants with improved root growth and reduced Al accumulation in root tips. Thus, we have discovered a new way of making rapeseed, an important crop, more tolerant to Al stress.
Keywords: Brassica napus, Aluminium tolerance, ALMT, root, Hairy root
Received: 22 Sep 2025; Accepted: 20 Nov 2025.
Copyright: © 2025 Cao, Liu, Yong, Liu, Ren, Liu, Coates and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Nannan Li, linannan2013@swu.edu.cn
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