Wang Shufeng, Wang Tao, Gao Lan, Du Hongxia, Wang Dingyong, Ma Ming, Rennenberg Heinz
Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing 400715, China.
Chongqing Key Laboratory of Innovative Application of Genetic Technology, College of Resources and Environment, Southwest University, No. 2, Tiansheng Road, Beibei District, Chongqing 400715, China.
Tree Physiol. 2025 Jan 25;45(1). doi: 10.1093/treephys/tpae166.
Iron plaques on the root surface can promote or inhibit the absorption and accumulation of heavy metals by plants. However, the mechanism by which iron regulates the response of Robinia pseudoacacia to mercury (Hg) has not been elucidated, which hinders its application in divalent Hg (Hg2+) removal from Hg-contaminated soil. In this study, association analyses between transcriptome and metabolome were used to investigate effects of iron on the rhizosphere microenvironment and performance of R. pseudoacacia to assess its potential for Hg2+ removal. The results showed that the addition of 10 mg kg-1 iron significantly increased the development of iron plaques on the root surface and reduced the secretion of low-molecular-weight organic acids by roots, thereby changing rhizosphere soil characteristics and decreasing total Hg in roots. In addition, the secretion of choline supported signal transduction and enhanced the interaction between R. pseudoacacia and rhizobia, thereby inducing resistance to Hg2+. Anti-oxidative enzyme activities were increased and Hg2+ exposure of plants was reduced. Enhanced Hg2+ resistance was indicated by improved photosynthesis and growth, despite promoted xylem loading and transport of Hg2+, resulting in its accumulation in aboveground tissues, which is essential for Hg2+ removal. These results indicate that iron addition has a great potential to improve the growth of R. pseudoacacia in Hg-contaminated soil and promote the accumulation of Hg2+ in aboveground tissues for phytoremediation approaches.
根表面的铁膜可促进或抑制植物对重金属的吸收和积累。然而，铁调节刺槐对汞（Hg）响应的机制尚未阐明，这阻碍了其在从汞污染土壤中去除二价汞（Hg2+）方面的应用。在本研究中，利用转录组和代谢组关联分析来研究铁对刺槐根际微环境和性能的影响，以评估其去除Hg2+的潜力。结果表明，添加10 mg kg-1铁显著增加了根表面铁膜的形成，并减少了根系低分子量有机酸的分泌，从而改变了根际土壤特性并降低了根中总汞含量。此外，胆碱的分泌支持信号转导并增强了刺槐与根瘤菌之间的相互作用，从而诱导对Hg2+的抗性。抗氧化酶活性增加，植物对Hg2+的暴露减少。尽管Hg2+向木质部的装载和运输增加，导致其在地上组织中积累，但光合作用和生长改善表明对Hg2+的抗性增强，这对于Hg2+的去除至关重要。这些结果表明，添加铁对于改善刺槐在汞污染土壤中的生长以及促进地上组织中Hg2+的积累以用于植物修复方法具有巨大潜力。
