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, PR China.
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, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China.
Environ Pollut. 2022 Mar 15;297:118818. doi: 10.1016/j.envpol.2022.118818. Epub 2022 Jan 8.
Iron (Fe) is an essential nutrient for living organisms and Fe deficiency is a worldwide problem for the health of both rice and humans. Zinc (Zn) contamination in agricultural soils is frequently observed. Here, we studied Fe isotope compositions and transcript levels of Fe transporter genes in rice growing in nutrient solutions having a range of Zn concentrations. Our results show Zn stress reduces Fe uptake by rice and drives its δFe value to that of the nutrient solution. These observations can be explained by the weakened Fe(II) uptake through Strategy I but enhanced Fe(III) uptake through Strategy II due to the competition between Zn and Fe(II) combining with OsIRT1 (Fe(II) transporter) in root, which is supported by the downregulated expression of OsIRT1 and upregulated expression of OsYSL15 (Fe(III) transporter). Using a mass balance box model, we also show excess Zn reduces Fe(II) translocation in phloem and its remobilization from senescent leaf, indicating a competition of binding sites on nicotianamine between Zn and Fe(II). This study provides direct evidence that how Zn regulates Fe uptake and translocation in rice and is of practical significance to design strategies to treat Fe deficiency in rice grown in Zn-contaminated soils.
铁（Fe）是生物体必需的营养物质，Fe 缺乏是影响水稻和人类健康的全球性问题。农业土壤中的锌（Zn）污染经常被观察到。在这里，我们研究了在具有不同 Zn 浓度的营养液中生长的水稻的 Fe 同位素组成和 Fe 转运蛋白基因的转录水平。我们的结果表明，Zn 胁迫会降低水稻对 Fe 的吸收，并使水稻的 δFe 值与营养液的 δFe 值趋同。这些观察结果可以通过以下机制得到解释：根中 Zn 和 Fe(II)与 OsIRT1（Fe(II)转运蛋白）的结合竞争导致通过策略 I 的 Fe(II)摄取减弱，同时通过策略 II 的 Fe(III)摄取增强，这得到了 OsIRT1 下调表达和 OsYSL15（Fe(III)转运蛋白）上调表达的支持。我们还使用质量平衡箱模型表明，过量的 Zn 减少了韧皮部中 Fe(II)的转运及其从衰老叶片中的再利用，这表明在植物螯合肽上，Zn 和 Fe(II)的结合位点存在竞争。这项研究提供了直接证据，证明了 Zn 如何调节水稻中的 Fe 吸收和转运，对于设计在 Zn 污染土壤中种植的水稻治疗 Fe 缺乏的策略具有实际意义。
