Plants must tightly regulate iron (Fe) sensing, acquisition, transport, mobilization, and storage to ensure sufficient levels of this essential micronutrient. POPEYE (PYE) is an iron responsive transcription factor that positively regulates the iron deficiency response, while also repressing genes essential for maintaining iron homeostasis. However, little is known about how PYE plays such contradictory roles. Under iron-deficient conditions, pPYE:GFP accumulates in the root pericycle while pPYE:PYE-GFP is localized to the nucleus in all Arabidopsis (Arabidopsis thaliana) root cells, suggesting that PYE may have cell-specific dynamics and functions. Using scanning fluorescence correlation spectroscopy and cell-specific promoters, we found that PYE-GFP moves between different cells and that the tendency for movement corresponds with transcript abundance. While localization to the cortex, endodermis, and vasculature is required to manage changes in iron availability, vasculature and endodermis localization of PYE-GFP protein exacerbated pye-1 defects and elicited a host of transcriptional changes that are detrimental to iron mobilization. Our findings indicate that PYE acts as a positive regulator of iron deficiency response by regulating iron bioavailability differentially across cells, which may trigger iron uptake from the surrounding rhizosphere and impact root energy metabolism.

中文翻译：

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POPEYE 细胞间定位介导细胞特异性缺铁反应。

植物必须严格调节铁 (Fe) 的感应、获取、运输、动员和储存，以确保这种必需微量营养素的充足水平。POPEYE (PYE) 是一种铁反应性转录因子，可积极调节缺铁反应，同时抑制维持铁稳态所必需的基因。然而，人们对 PYE 如何扮演如此矛盾的角色知之甚少。在缺铁条件下，pPYE:GFP在根中柱鞘中积累，而pPYE:PYE-GFP在所有拟南芥(Arabidopsis thaliana)根细胞中定位于细胞核，这表明PYE可能具有细胞特异性的动力学和功能。使用扫描荧光相关光谱和细胞特异性启动子，我们发现 PYE-GFP 在不同细胞之间移动，并且移动趋势与转录本丰度相对应。虽然需要定位到皮质、内皮层和脉管系统来管理铁可用性的变化，但 PYE-GFP 蛋白的脉管系统和内皮层定位加剧了 pye-1 缺陷，并引发了一系列不利于铁动员的转录变化。我们的研究结果表明，PYE 通过差异调节细胞间铁的生物利用度，充当缺铁反应的正调节剂，这可能会触发周围根际的铁吸收并影响根部能量代谢。