National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
J Environ Sci (China). 2024 Jan;135:10-25. doi: 10.1016/j.jes.2023.01.001. Epub 2023 Jan 7.
Mercury (Hg) is one of the most dangerous contaminants and has sparked global concern since it poses a health risk to humans when consumed through rice. Sulfur (S) is a crucial component for plant growth, and S may reduce Hg accumulation in rice grains. However, the detailed effects of S and the mechanisms underlying S-mediated responses in Hg-stressed rice plants remain unclear. Currently, to investigate the effects of S addition on rice growth, Hg accumulation, physiological indexes, and gene expression profiles, rice seedlings were hydroponically treated with Hg (20 µmol/L HgCl) and Hg plus elemental sulfur (100 mg/L). S application significantly reduced Hg accumulation in Hg-stressed rice roots and alleviated the inhibitory effects of Hg on rice growth. S addition significantly reduced Hg-induced reactive oxygen species generation, membrane lipid peroxidation levels, and activities of antioxidant enzymes while increasing glutathione content in leaves. Transcriptomic analysis of roots identified 3,411, 2,730, and 581 differentially expressed genes in the control (CK) vs. Hg, CK vs. Hg + S, and Hg vs. Hg + S datasets, respectively. The pathway of S-mediated biological metabolism fell into six groups: biosynthesis and metabolism, expression regulation, transport, stimulus response, oxidation reduction, and cell wall biogenesis. The majority of biological process-related genes were upregulated under Hg stress compared with CK treatment, but downregulated in the Hg + S treatment. The results provide transcriptomic and physiological evidence that S may be critical for plant Hg stress resistance and will help to develop strategies for reduction or phytoremediation of Hg contamination.
汞（Hg）是最危险的污染物之一，由于它会通过食用大米对人类健康造成威胁，因此引起了全球关注。硫（S）是植物生长的关键组成部分，S 可能会减少大米中汞的积累。然而，S 的详细作用以及 S 介导的汞胁迫水稻植物响应的机制仍不清楚。目前，为了研究 S 添加对水稻生长、Hg 积累、生理指标和基因表达谱的影响，采用水培法用 Hg（20 μmol/L HgCl）和 Hg 加元素硫（100 mg/L）处理水稻幼苗。S 的施加显著降低了汞胁迫水稻根系中的 Hg 积累，并减轻了 Hg 对水稻生长的抑制作用。S 的添加显著降低了 Hg 诱导的活性氧生成、膜脂过氧化水平和抗氧化酶活性，同时增加了叶片中的谷胱甘肽含量。根的转录组分析鉴定出在对照（CK）与 Hg、CK 与 Hg+S 和 Hg 与 Hg+S 数据集之间分别有 3411、2730 和 581 个差异表达基因。S 介导的生物代谢途径分为六个组：生物合成和代谢、表达调控、运输、刺激反应、氧化还原和细胞壁生物发生。与 CK 处理相比，Hg 胁迫下大多数与生物过程相关的基因上调，但在 Hg+S 处理下下调。结果提供了转录组和生理学证据，表明 S 对植物汞胁迫抗性至关重要，并将有助于开发减少或植物修复 Hg 污染的策略。
