Iron (Fe) is an essential micronutrient for plant life and development. However, in soil, Fe bioavailability is often limited and variable in space and time, thus different regions of the same root system might be exposed to different nutrient provisions. Few studies showed that the response to variable Fe provision is controlled at local and systemic levels, albeit the identity of the signals involved is still elusive. Iron itself was suggested as local mediator, whilst hormones were proposed for the long-distance signalling pathway. Therefore, the aim of this work was to assess whether Fe, when localized in a restricted area of the root system, might be involved in both local and systemic signaling. The combination of resupply experiments in a split-root system, the use of 57Fe isotope and chemical imaging techniques allowed tracing Fe movement within cucumber plants. Soon after the resupply, Fe is distributed to the whole plant, likely to overcome a minimum Fe concentration threshold aimed at repressing the deficiency response. Iron was then preferentially translocated to leaves and, only afterwards, the root system was completely resupplied. Collectively, these observations might thus highlight a root-to-shoot-to-root Fe translocation route in cucumber plants grown on a patchy nutrient substrate.

中文翻译：

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在异质 Fe 条件下生长的黄瓜植株中的根-茎-根 Fe 易位

铁（Fe）是植物生命和发育必不可少的微量营养素。然而，在土壤中，铁的生物利用度通常是有限的，并且在空间和时间上是可变的，因此同一根系的不同区域可能暴露于不同的养分供应。很少有研究表明对可变 Fe 供应的反应是在局部和全身水平上控制的，尽管所涉及的信号的身份仍然难以捉摸。铁本身被认为是局部介质，而激素被认为是长距离信号通路。因此，这项工作的目的是评估 Fe，当定位在根系统的受限区域时，是否可能参与局部和全身信号传导。分根系统中再补给实验的组合，使用 57Fe 同位素和化学成像技术可以追踪黄瓜植物中 Fe 的运动。补给后不久，铁被分配到整个植物，可能会克服旨在抑制缺乏反应的最小铁浓度阈值。然后铁优先转移到叶子上，然后才完全重新供应根系。总的来说，这些观察结果可能因此突出了在斑驳营养基质上生长的黄瓜植物中根到茎到根的 Fe 易位途径。