Anhui Province Key Laboratory of Rice Germplasm Innovation and Molecular Improvement (Rice Research Institute, Anhui Academy of Agricultural Sciences), Hefei 230031, PR China.
School of Life Sciences, Centre for Cell & Developmental Biology, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong.
J Hazard Mater. 2024 Dec 5;480:136073. doi: 10.1016/j.jhazmat.2024.136073. Epub 2024 Oct 6.
Cadmium (Cd) contamination poses a substantial threat to crop yields and human health. While magnesium hydride (MgH) has been reported as a hydrogen (H) donor that promotes plant growth under heavy metal contamination, its role in rice remains elusive. Herein, seedlings of Oryza sativa L. Japonica variety Zhonghua 11 (ZH11) were selected and exposed to 20 µL of 1-mol/L cadmium chloride (CdCl) solution via hydroponics to simulate Cd stress. Meanwhile, 0.1 mg of MgH was used to slow-release H to the experimental group to explore its potential effects on rice over a 2-week period. The results indicated that Cd exposure severely inhibited the growth and development of ZH11 rice seedlings. However, the exogenous slow-release of H from MgH effectively mitigated this inhibitory effect by restoring the balance of reactive oxygen species (ROS), maintaining endogenous H homeostasis, and supporting the photosynthetic system. High-performance liquid chromatography analysis revealed that exogenous H reduces mA RNA methylation levels in mRNA under Cd stress. Consequently, MeRIP-seq was conducted to investigate the effect of Cd exposure in rice in the presence and absence of H. The mA modifications were enriched at the start codon, stop codon, and 3' UTR. By integrating RNA-seq data, 118 transcripts were identified as differentially methylated and expressed genes under Cd stress. These gene annotations were associated with ROS, biological stress, and hormonal responses. Notably, 297 differentially methylated and expressed genes were identified under Cd stress in the presence of H, linked to heavy metals, protein kinases, and calcium signaling regulation. Cd strongly activates the MAPK pathway in response to stress. Exogenous H reduces Cd accumulation as well as enhances plant tolerance and homeostasis by lowering mA levels, thereby decreasing the mRNA stability of these genes. Our findings indicate that MgH, by supplying H, regulates gene expression through mA RNA methylation and confers Cd tolerance in rice. This study provides potential candidate genes for studying the remediation of heavy metal pollution in plants.
镉（Cd）污染对作物产量和人类健康构成了重大威胁。虽然已经报道了氢化镁（MgH）是一种在重金属污染下促进植物生长的氢（H）供体，但它在水稻中的作用仍不清楚。在此，选择了粳稻品种 Zhonghua 11（ZH11）的水稻幼苗，并通过水培法将 20µL 的 1mol/L 氯化镉（CdCl）溶液暴露于模拟 Cd 胁迫的溶液中。同时，向实验组中添加 0.1mg 的 MgH 以缓慢释放 H，以在两周的时间内探索其对水稻的潜在影响。结果表明，Cd 暴露严重抑制了 ZH11 水稻幼苗的生长和发育。然而，MgH 缓慢释放的外源 H 通过恢复活性氧（ROS）的平衡、维持内源性 H 稳态和支持光合作用系统，有效缓解了这种抑制作用。高效液相色谱分析显示，外源 H 降低了 Cd 胁迫下 mRNA 中的 mA RNA 甲基化水平。因此，在存在和不存在 H 的情况下，进行了 MeRIP-seq 以研究 Cd 暴露对水稻的影响。mA 修饰在起始密码子、终止密码子和 3'UTR 处富集。通过整合 RNA-seq 数据，鉴定出 118 个转录本在 Cd 胁迫下差异甲基化和表达。这些基因注释与 ROS、生物应激和激素反应有关。值得注意的是，在存在 H 的情况下，在 Cd 胁迫下鉴定出 297 个差异甲基化和表达的基因，这些基因与重金属、蛋白激酶和钙信号转导调节有关。Cd 强烈激活 MAPK 途径以应对应激。外源 H 通过降低 mA 水平来减少 Cd 积累，增强植物耐受性和内稳态，从而降低这些基因的 mRNA 稳定性。我们的研究结果表明，MgH 通过提供 H，通过 mA RNA 甲基化来调节基因表达，并赋予水稻 Cd 耐受性。这项研究为研究植物重金属污染修复提供了潜在的候选基因。
