Iron Availability within the Leaf Vasculature Determines the Magnitude of Iron Deficiency Responses in Source and Sink Tissues in Arabidopsis
Iron Availability within the Leaf Vasculature Determines the Magnitude of Iron Deficiency Responses in Source and Sink Tissues in Arabidopsis
复制标题
拟南芥叶脉管系统内的铁利用率决定了源组织和库组织缺铁反应的程度
DOI：
10.1093/pcp/pcac046
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发表时间：
2022
影响因子：
4.9
通讯作者：
Mendoza-Cozatl, David G.
中科院分区：
文献类型：
--
作者：
Nguyen, Nga T.;Khan, Mather A.;Castro–Guerrero, Norma A.;Chia, Ju-Chen;Vatamaniuk, Olena K.;Mari, Stephane;Jurisson, Silvia S.;Mendoza-Cozatl, David G.
铁（Fe）在植物中的吸收和转运是由尚未完全理解的复杂机制微调的。在拟南芥中，根水平铁稳态的局部调控已经被广泛研究，并且比系统的茎到根调控更容易理解。根系仅仅是一个吸收组织，依赖于从源组织转运的光合产物，而茎部系统是一个更复杂的组织，其中吸收组织和源组织同步发生。在本研究中，为了更好地了解叶片铁缺乏反应，我们在韧皮部加载细胞（proSUC2::AtZIP5）中过表达锌/铁调节转运蛋白样蛋白（ZIP5），一种铁/锌转运蛋白，并确定了汇（幼叶和根）和源组织（叶）铁缺乏反应的时间。在根生长试验中，伴细胞中过表达zip5的转基因系对缺铁的敏感性增加。此外，与野生型（WT）植物相比，幼叶和根（汇组织）对缺铁的转录反应延迟或减弱。我们还利用拟南芥突变体4x-1来探索铁在相反情况下的转录反应，在这种情况下，铁保留在脉管系统中，但以不可用的沉淀形式存在。与proSUC2:: atzip5植株相比，nas4x-1幼苗叶片和根系表现出强烈的铁缺乏响应，而成熟叶片则表现出延迟和抑制的铁缺乏响应。总之，我们的数据提供的证据表明，叶片内的铁感应也可能以特定于叶片的方式局部发生。
Iron (Fe) uptake and translocation in plants are fine-tuned by complex mechanisms that are not yet fully understood. InArabidopsis thaliana, local regulation of Fe homeostasis at the root level has been extensively studied and is better understood than the systemic shoot-to-root regulation. While the root system is solely a sink tissue that depends on photosynthates translocated from source tissues, the shoot system is a more complex tissue, where sink and source tissues occur synchronously. In this study, and to gain better insight into the Fe deficiency responses in leaves, we overexpressed Zinc/Iron-regulated transporter-like Protein (ZIP5), an Fe/Zn transporter, in phloem-loading cells (proSUC2::AtZIP5) and determined the timing of Fe deficiency responses in sink (young leaves and roots) and source tissues (leaves). Transgenic lines overexpressingZIP5in companion cells displayed increased sensitivity to Fe deficiency in root growth assays. Moreover, young leaves and roots (sink tissues) displayed either delayed or dampened transcriptional responses to Fe deficiency compared to wild-type (WT) plants. We also took advantage of theArabidopsismutantnas4x-1to explore Fe transcriptional responses in the opposite scenario, where Fe is retained in the vasculature but in an unavailable and precipitated form. In contrast to proSUC2::AtZIP5plants,nas4x-1young leaves and roots displayed a robust and constitutive Fe deficiency response, while mature leaves showed a delayed and dampened Fe deficiency response compared to WT plants. Altogether, our data provide evidence suggesting that Fe sensing within leaves can also occur locally in a leaf-specific manner.