水稻根际细胞外活性氧产量的日变化,Environmental Science & Technology

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水稻根际细胞外活性氧产量的日变化
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-05-20 , DOI: 10.1021/acs.est.2c00005
Hengyi Dai _{1,

2,

3,

4} , Binbin Wu ₁ , Baoliang Chen ₁ , Bin Ma _{1,

2,

3,

4} , Chiheng Chu ₁

Affiliation

活性氧（ROS）在地球上无处不在，并驱动着许多以氧化还原为中心的生物地球化学过程。湿地植物的根际是氧和电子交换的高度动态界面，为产生活性氧的先例奠定了基础，但根际是否产生细胞外活性氧仍是未知数。在这里，我们设计了一种微流控芯片装置，以空间和时间分辨率检测水稻根际的原位ROS 产生。荧光成像清楚地显示了根际 ROS 生成的热点。羟基自由基的形成浓度 ( ^• OH, 一种代表性的 ROS, 10 ^–6 M) 与经典光化学途径 (10 ^–6–10 ^–7M）在水生系统中，因此强调根际作为 ROS 生产的一个未被识别的热点。此外，根际活性氧的产生表现出昼夜波动，同时随着溶解氧、氧化还原电位和 pH 值的波动，这些波动都是由白天根部附近的径向氧损失驱动的。在天然土壤中培养的水稻根际证实了 ROS 的产生和昼夜波动。我们证明了细胞外 ROS 的产生是由根释放的氧气和微生物呼吸释放细胞外电子之间的相互作用触发的，而铁矿物和有机物可能在储存和穿梭电子中起关键作用。我们的研究结果强调根际是一个广泛但以前未被重视的 ROS 生产热点，

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Diel Fluctuation of Extracellular Reactive Oxygen Species Production in the Rhizosphere of Rice

Reactive oxygen species (ROS) are ubiquitous on earth and drive numerous redox-centered biogeochemical processes. The rhizosphere of wetland plants is a highly dynamic interface for the exchange of oxygen and electrons, presenting the basis of the precedent for ROS production, yet whether extracellular ROS are produced in the rhizosphere remains unknown. Here, we designed a microfluidic chip setup to detect in-situ ROS productions in the rhizosphere of rice with spatial and temporal resolutions. Fluorescence imaging clearly displayed the hot spots of ROS generation in the rhizosphere. The formation concentration of the hydroxyl radical (^•OH, a representative ROS, 10^–6 M) was comparable to those by the classical photochemical route (10^–6–10^–7 M) in aquatic systems, therefore highlighting the rhizosphere as an unrecognized hotspot for ROS production. Moreover, the rhizosphere ROS production exhibits diel fluctuation, which simultaneously fluctuated with dissolved oxygen, redox potential, and pH, all driven by radial oxygen loss near the root in the daytime. The production and diel fluctuation of ROS were confirmed in the rhizosphere of rice root incubated in natural soils. We demonstrated that the extracellular ROS production was triggered by the interplay between root-released oxygen and microbial respiration released extracellular electrons, while iron mineral and organic matter might play key roles in storing and shuttling electrons. Our results highlight the rhizosphere as a widespread but previously unappreciated hotspot for ROS production, which may affect pollutant redox dynamics and biogeochemical processes in soils.

更新日期：2022-05-20

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