DataSheet_1_The effects of different iron and phosphorus treatments on the formation and morphology of iron plaque in rice roots (Oryza sativa L).docx

IntroductionRice (Oryza sativa L.) is a pivotal cereal crop worldwide. It relies heavily on the presence of iron plaque on its root surfaces for optimal growth and enhanced stress resistance across diverse environmental conditions.
MethodTo study the crystallographic aspects of iron plaque formation on rice roots, the concentrations of Fe2+ and PO43- were controlled in this study. The effects of these treatments were assessed through comprehensive analyzes encompassing root growth status, root surface iron concentration, root vitality, enzyme activities, and microstructural characteristics using advanced techniques such as root analysis, scanning electron microscopy (SEM), and ultrathin section transmission electron microscopy (TEM).
ResultsThe results demonstrated that an increase in the Fe2+ concentration or a decrease in the PO43- concentration in the nutrient solution led to improvements in various root growth indicators. There was an elevation in the DCB (dithionite-citrate–bicarbonate) iron content within the roots, enhanced root vitality, and a significant increase in the activities of the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) enzymes. Moreover, as the Fe2+ concentration increased, amorphous iron oxide minerals on the root surface were gradually transformed into ferrihydrite particles with sizes of approximately 200 nm and goethite particles with sizes of approximately 5 μm. This study showed that an increase in the Fe2+ concentration and a decrease in the PO43- concentration led to the formation of substantial iron plaque on the root surfaces. It is noteworthy that there was a distinct gap ranging from 0.5 to 3 μm between the iron plaque formed through PO43- treatment and the cellular layer of the root surface.
DiscussionThis study elucidated the impacts of Fe2+ and PO43- treatments on the formation, structure, and morphology of the iron plaque while discerning variations in the spatial proximity between the iron plaque and root surface under different treatment conditions.

引言
水稻（Oryza sativa L.）是全球至关重要的禾谷类粮食作物，其根系表面形成的铁膜对植株在多样环境下的最优生长与逆境抗性提升具有关键作用。
材料与方法
为探究水稻根系铁膜形成的晶体学特征，本研究控制了营养液中Fe²+与PO₄³-的浓度。通过涵盖根系生长状态、根表铁浓度、根系活力、酶活性及微观结构特征的综合分析，并采用根系分析、扫描电子显微镜（Scanning Electron Microscopy, SEM）、超薄切片透射电子显微镜（Transmission Electron Microscopy, TEM）等先进技术，对各处理的效应进行评估。
结果
结果表明，营养液中Fe²+浓度升高或PO₄³-浓度降低，可改善多项根系生长指标。根系内的连二亚硫酸钠-柠檬酸钠-碳酸氢盐（dithionite-citrate–bicarbonate, DCB）铁含量升高，根系活力增强，超氧化物歧化酶（Superoxide Dismutase, SOD）、过氧化物酶（Peroxidase, POD）及过氧化氢酶（Catalase, CAT）的活性均显著提升。此外，随着Fe²+浓度升高，根表的无定形氧化铁矿物逐渐转化为粒径约200 nm的水铁矿（ferrihydrite）颗粒与粒径约5 μm的针铁矿（goethite）颗粒。本研究发现，Fe²+浓度升高与PO₄³-浓度降低均可促使根表面形成大量铁膜。值得注意的是，经PO₄³-处理形成的铁膜与根表细胞层之间存在0.5至3 μm的明显间隙。
讨论
本研究阐明了Fe²+与PO₄³-处理对铁膜形成、结构与形貌的影响，并揭示了不同处理条件下铁膜与根表空间毗邻关系的差异。