Institute of Plant Nutrition, Faculty of Natural Sciences, Leibniz University Hannover, Herrenhäuser Str. 2, 30419, Hannover, Germany.
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Plant Reproductive Biology; Corrensstr. 3; D-06466 Seeland/OT, Gatersleben, Germany.
Sci Rep. 2020 Mar 19;10(1):5079. doi: 10.1038/s41598-020-61718-4.
Gramineous plants take up silicon (Si) that enhances the formation of exodermal Casparian bands (CBs) in the roots of rice (Oryza sativa L.). Furthermore, it is known that Si supply reduces the concentration of Fe in rice shoots. We hypothesized that the Si-enhanced CB formation in the exodermis reduces in the flux of Fe in the apoplast and the uptake of Fe loaded deoxymugineic acid. Thus, the effect of silicic acid supply at varied Fe concentrations and Fe forms was investigated in nutrient solution. The Fe concentrations in the shoot and apoplastic Fe concentrations in the root were determined and an Affymetrix GeneChip experiment was carried out together with qRT-PCR measurements for observation of transcriptomic reactions. Additionally, the Fe uptake of an overexpression mutant of OsABCG25 with an enhanced exodermal CB formation was investigated. The application of silicic acid reduced the Fe concentrations in shoot DM independently of the supplied Fe concentration and Fe form. As a reaction to the Fe shortage, the full cascade of Fe-homeostasis-related genes in the roots was upregulated. Silicic acid supply also decreased the apoplastic Fe concentrations in roots. In addition, an overexpression mutant of OsABCG25 with an enhanced CB formation showed a reduced uptake of Fe in excess Fe conditions. The results suggest that the Si-induced CB formation in the exodermis hampers the flux of Fe into the apoplast of the cortex and, thus, Fe uptake of rice grown in nutrient solution which is reflected in the upregulation of Fe homeostasis-related genes.
禾本科植物吸收硅（Si），增强水稻（Oryza sativa L.）根部表皮 Casparian 带（CB）的形成。此外，已知 Si 供应会降低水稻地上部分的铁浓度。我们假设 Si 增强的表皮 CB 形成会减少质外体中铁的通量和去氧麦根酸负载的铁的吸收。因此，在营养液中研究了不同铁浓度和铁形式下硅酸供应的影响。测定了地上部分的铁浓度和根的质外体铁浓度，并进行了 Affymetrix GeneChip 实验和 qRT-PCR 测量，以观察转录组反应。此外，还研究了 OsABCG25 的过表达突变体（具有增强的表皮 CB 形成）的铁吸收。硅酸的应用独立于供应的铁浓度和铁形式，降低了地上部分 DM 中的铁浓度。作为对铁缺乏的反应，根系中完整的铁稳态相关基因级联被上调。硅酸供应还降低了根的质外体铁浓度。此外，具有增强 CB 形成的 OsABCG25 的过表达突变体在过量铁条件下显示出铁吸收减少。结果表明，Si 诱导的表皮 CB 形成阻碍了铁进入皮层质外体的通量，从而阻碍了营养液中生长的水稻的铁吸收，这反映在铁稳态相关基因的上调上。
