Abstract Pteris vittata (PV) and Pteris quadriaurita (PQ) are reported to hyperaccumulate arsenic (As) when grown in As-rich soil. Yet, little is known about the impact of their unique As accumulation mechanisms on As transformations and cycling at the soil-root interface. Using a combined approach of two-dimensional (2D), sub-mm scale solute imaging of arsenite (AsIII), arsenate (AsV), phosphorus (P), manganese (Mn), iron (Fe) and oxygen (O2), we found localized patterns of AsIII/AsV redox transformations in the PV rhizosphere (AsIII/AsV ratio of 0.57) compared to bulk soil (AsIII/AsV ratio of ≤0.04). Our data indicate that the high As root uptake, translocation and accumulation from the As-rich experimental soil (2080 mg kg−1) to PV fronds (6986 mg kg−1) induced As detoxification via AsV reduction and AsIII root efflux, leading to AsIII accumulation and re-oxidation to AsV in the rhizosphere porewater. This As cycling mechanism is linked to the reduction of O2 and MnIII/IV (oxyhydr)oxides resulting in decreased O2 levels and increased Mn solubilization along roots. Compared to PV, we found 4-fold lower As translocation to PQ fronds (1611 mg kg−1), 2-fold lower AsV depletion in the PQ rhizosphere, and no AsIII efflux from PQ roots, suggesting that PQ efficiently controls As uptake to avoid toxic As levels in roots. Analysis of root exudates obtained from soil-grown PV showed that As acquisition by PV roots was not associated with phytic acid release. Our study demonstrates that two closely-related As-accumulating ferns have distinct mechanisms for As uptake modulating As cycling in As-rich environments.

中文翻译：

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Pteris vittata 和 Pteris quadriaurita 根际砷氧化还原转化和循环

摘要 Pteris vittata (PV) 和 Pteris quadriaurita (PQ) 据报道在富含砷的土壤中生长时会超积累砷 (As)。然而，人们对其独特的砷积累机制对土壤-根界面处砷转化和循环的影响知之甚少。使用亚砷酸盐 (AsIII)、砷酸盐 (AsV)、磷 (P)、锰 (Mn)、铁 (Fe) 和氧 (O2) 的二维 (2D)、亚毫米级溶质成像的组合方法，我们发现与大块土壤（AsIII/AsV 比率≤0.04）相比，PV 根际中 AsIII/AsV 氧化还原转化的局部模式（AsIII/AsV 比率为 0.57）。我们的数据表明，从富含 As 的实验土壤 (2080 mg kg-1) 到 PV 叶 (6986 mg kg-1) 的高 As 根吸收、易位和积累通过 AsV 减少和 AsIII 根外流诱导 As 解毒，导致 AsIII 在根际孔隙水中积累并重新氧化为 AsV。这种 As 循环机制与 O2 和 MnIII/IV（羟基）氧化物的减少有关，从而导致 O2 水平降低和沿根部的 Mn 溶解增加。与 PV 相比，我们发现对 PQ 叶的 As 易位降低了 4 倍（1611 mg kg-1），PQ 根际中 AsV 消耗降低了 2 倍，并且没有来自 PQ 根的 AsIII 流出，表明 PQ 有效地控制 As避免根中有毒的砷含量。从土壤生长的 PV 中获得的根系分泌物的分析表明，PV 根获得的砷与植酸释放无关。我们的研究表明，两种密切相关的 As 积累蕨类植物在富含 As 的环境中具有不同的 As 吸收调节 As 循环的机制。这种 As 循环机制与 O2 和 MnIII/IV（羟基）氧化物的减少有关，从而导致 O2 水平降低和沿根部的 Mn 溶解增加。与 PV 相比，我们发现对 PQ 叶的 As 易位降低了 4 倍（1611 mg kg-1），PQ 根际中 AsV 消耗降低了 2 倍，并且没有来自 PQ 根的 AsIII 流出，表明 PQ 有效地控制 As避免根中有毒的砷含量。从土壤生长的 PV 中获得的根系分泌物的分析表明，PV 根获得的砷与植酸释放无关。我们的研究表明，两种密切相关的 As 积累蕨类植物在富含 As 的环境中具有不同的 As 吸收调节 As 循环的机制。这种 As 循环机制与 O2 和 MnIII/IV（羟基）氧化物的减少有关，从而导致 O2 水平降低和沿根部的 Mn 溶解增加。与 PV 相比，我们发现对 PQ 叶的 As 易位降低了 4 倍（1611 mg kg-1），PQ 根际中 AsV 消耗降低了 2 倍，并且没有来自 PQ 根的 AsIII 流出，表明 PQ 有效地控制 As避免根中有毒的砷含量。从土壤生长的 PV 中获得的根系分泌物的分析表明，PV 根获得的砷与植酸释放无关。我们的研究表明，两种密切相关的 As 积累蕨类植物在富含 As 的环境中具有不同的 As 吸收调节 As 循环的机制。