Iron Lung: How Rice Roots Induce Iron Redox Changes in the Rhizosphere and Create Niches for Microaerophilic Fe(II)-Oxidizing Bacteria
Iron Lung: How Rice Roots Induce Iron Redox Changes in the Rhizosphere and Create Niches for Microaerophilic Fe(II)-Oxidizing Bacteria
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DOI：
10.1021/acs.estlett.9b00403
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发表时间：
2019-10-01
影响因子：
10.9
通讯作者：
Schmidt, Caroline
中科院分区：
文献类型：
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作者：
Maisch, Markus;Lueder, Ulf;Schmidt, Caroline
虽然淹水稻田的特点是缺氧条件下，径向氧损失（ROL）从水稻根暂时氧化土壤根际。ROL不仅触发亚铁（Fe（II））的非生物氧化，而且还为微需氧Fe（II）氧化细菌（microFeOx）提供电子受体。这两个过程都有助于在根表面形成三价铁（Fe（III））铁菌斑。单根的氧化还原相互作用已被深入研究。然而，目前对整个根际ROL的时间分辨空间变化及其对氧化还原形态地球化学的影响知之甚少。在这里，我们展示了ROL如何时空演变和相关的Fe-氧化还原转换。应用非侵入性测量在一个透明的人工土壤中，我们能够看到相反的O-2和Fe（II）的梯度，从根表面延伸到根际10-25毫米。微氧区在整个根际范围内呈指数级扩大，为microFeOx创造了生态位。铁矿物形成和pH值，我们表明，根相关的ROL诱导铁氧化还原转化和周围的根和根际酸化相关。这些研究结果突出了水稻根际根系的动态性质，我们的方法时空解决了它们对水稻根际铁氧化还原化学和微生物生态位形成的影响。
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 O-2 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.