Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs/ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing 100081, PR China.
Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs/ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing 100081, PR China.
J Hazard Mater. 2021 Aug 15;416:126079. doi: 10.1016/j.jhazmat.2021.126079. Epub 2021 May 14.
Periodic flooding in paddy soils impacts redox behavior and induces variations in pe+pH levels. Manganese (Mn) is capable of reducing cadmium (Cd) uptake by rice. However, the processes involved in how Mn alters Cd mobilization under different pe+pH environments remain poorly understood. To investigate the mechanisms of Mn-mediated soil Cd-stabilization and subsequent inhibition of Cd uptake from flooded soils, we examined Cd immobilization in soil pot incubations, transcriptional changes in Cd-transport genes, and metabolomic analyses of roots and rhizosphere soils with or without Mn application. We found a decrease in extractable Cd concentration largely depended on irrigation-associated low pe+pH, exogenous Mn enhancement of Fe-Mn (oxyhydro)oxide-mediated Cd transformation, and Cd deposition in rice Fe/Mn plaques. Mn application led to striking effects on the expression of Cd-related genes eg. IRT, HMA, and NRAMP in rice root tissue. Exposure to Mn under variable pe+pH levels resulted in metabolic reprogramming of soil and rice roots. Mn induced amino acid synthesis in rice roots, leading to rhizosphere accumulation of free L-lysine, glycine, and glutamine, which can reportedly bind metal ions, forming complexes with Cd. Thus, secreted amino acids, low pe+pH, and free Mn can together comprise a multi-faceted approach to managing Cd toxicity in rice.
稻田的周期性淹水会影响氧化还原行为，并导致 pe+pH 值水平发生变化。锰（Mn）能够降低水稻对镉（Cd）的吸收。然而，在不同 pe+pH 环境下，Mn 如何改变 Cd 迁移的过程仍知之甚少。为了研究 Mn 介导的土壤 Cd 稳定化及其随后抑制淹水土壤中 Cd 吸收的机制，我们在土壤培养皿中研究了 Cd 的固定化，分析了 Cd 转运基因的转录变化，以及有无 Mn 应用时根和根际土壤的代谢组学分析。我们发现，可提取 Cd 浓度的降低主要取决于与灌溉相关的低 pe+pH、外源 Mn 增强 Fe-Mn（氧）氢氧化物介导的 Cd 转化以及 Cd 在水稻 Fe/Mn 斑块上的沉积。Mn 的应用对水稻根组织中 Cd 相关基因（如 IRT、HMA 和 NRAMP）的表达产生了显著影响。在不同 pe+pH 水平下暴露于 Mn 会导致土壤和水稻根的代谢重新编程。Mn 诱导了水稻根中氨基酸的合成，导致根际游离 L-赖氨酸、甘氨酸和谷氨酸的积累，据报道这些氨基酸可以结合金属离子，与 Cd 形成配合物。因此，分泌的氨基酸、低 pe+pH 和游离 Mn 可以共同构成一种多方面的方法来管理水稻中的 Cd 毒性。
