Although water-logged rice paddies are characterized by anoxic conditions, radial oxygen loss (ROL) from rice roots temporarily oxygenates the soil rhizosphere. ROL not only triggers the abiotic oxidation of ferrous iron (Fe(II)) but also provides the electron acceptor for microaerophilic Fe(II)-oxidizing bacteria (microFeOx). Both processes contribute to the formation of ferric (Fe(III)) iron plaque on root surfaces. Redox interactions at single roots have been studied intensively. However, temporally resolved spatial changes of ROL in the entire rhizosphere and the impact on redoximorphic biogeochemistry are currently poorly understood. Here, we show how ROL spatiotemporally evolves and correlates with Fe-redox transformations. Applying noninvasive measurements in a transparent artificial soil, we were able to visualize opposing O₂ and Fe(II) gradients that extend from the root surface 10–25 mm into the rhizosphere. The microoxic zone expanded exponentially in size throughout the entire rhizosphere creating niches for microFeOx. Following iron mineral formation and pH, we show that root-related ROL induces iron redox transformations on and around roots and correlates with rhizosphere acidification. These findings highlight the dynamic nature of roots in the rice plant rhizosphere, and our approach spatiotemporally resolved their impact on iron redox chemistry and microbial niche formation in the rice plant rhizosphere.

中文翻译：

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铁肺：水稻根系如何诱导根际铁氧化还原变化并为微需氧Fe（II）氧化细菌创造壁Create

尽管淹水的稻田以缺氧条件为特征，但稻根的径向氧损失（ROL）暂时使土壤根际充氧。ROL不仅触发亚铁（Fe（II））的非生物氧化，而且还为微需氧的Fe（II）氧化细菌（microFeOx）提供电子受体。这两个过程都有助于在根部表面形成三价铁（Fe（III））铁斑。深入研究了单根的氧化还原相互作用。然而，目前还不太了解ROL在整个根际中的时间分辨空间变化及其对氧化还原形态生物地球化学的影响。在这里，我们展示了ROL如何时空演化并与Fe-redox转换相关。在透明的人造土壤中应用非侵入性测量，我们能够可视化相对的O₂和Fe（II）梯度从根表面延伸10到25 mm到根际。微氧区的大小在整个根际呈指数增长，为microFeOx创造了生态位。继铁矿物质的形成和pH值之后，我们表明与根相关的ROL诱导根上和根周围的铁氧化还原转化，并与根际酸化相关。这些发现凸显了水稻植物根际中根的动态性质，我们的方法在时空上解决了它们对水稻植物根际中铁氧化还原化学和微生物生态位形成的影响。