There is a link between PAP/SAL retrograde pathway, ethylene signaling and Fe metabolism in Arabidopsis. Nuclear gene expression is regulated by a diversity of retrograde signals that travel from organelles to the nucleus in a lineal or classical model. One such signal molecule is 3'-phosphoadenisine-5'-phosphate (PAP) and it's in vivo levels are regulated by SAL1/FRY1, a phosphatase enzyme located in chloroplast and mitochondria. This metabolite inhibits the action of a group of exorribonucleases which participate in post-transcriptional gene expression regulation. Transcriptome analysis of Arabidopsis thaliana mutant plants in PAP-SAL1 pathway revealed that the ferritin genes AtFER1, AtFER3, and AtFER4 are up-regulated. In this work we studied Fe metabolism in three different mutants of the PAP/SAL1 retrograde pathway. Mutant plants showed increased Fe accumulation in roots, shoots and seeds when grown in Fe-sufficient condition, and a constitutive activation of the Strategy I Fe uptake genes. As a consequence, they grew more vigorously than wild type plants in Fe-deficient medium. However, when mutant plants grown in Fe-deficient conditions were sprayed with Fe in their leaves, they were unable to deactivate root Fe uptake. Ethylene synthesis inhibition revert the constitutive Fe uptake phenotype. We propose that there is a link between PAP/SAL pathway, ethylene signaling and Fe metabolism.

中文翻译：

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PAP/SAL1 逆行信号通路参与铁稳态。

拟南芥 PAP/SAL 逆行途径、乙烯信号和铁代谢之间存在联系。核基因表达受多种逆行信号的调节，这些逆行信号在线性或经典模型中从细胞器传播到细胞核。一个这样的信号分子是 3'-磷酸腺苷-5'-磷酸 (PAP)，它的体内水平受 SAL1/FRY1 调节，SAL1/FRY1 是一种位于叶绿体和线粒体中的磷酸酶。该代谢物抑制一组参与转录后基因表达调节的外切核糖核酸酶的作用。PAP-SAL1 通路中拟南芥突变植物的转录组分析显示铁蛋白基因 AtFER1、AtFER3 和 AtFER4 上调。在这项工作中，我们研究了 PAP/SAL1 逆行途径的三种不同突变体中的铁代谢。当在铁充足的条件下生长时，突变植物在根、芽和种子中的铁积累增加，并且策略 I 铁摄取基因的组成型激活。结果，它们在缺铁培养基中比野生型植物生长得更旺盛。然而，当在缺铁条件下生长的突变植物在叶子中喷洒铁时，它们无法使根系对铁的吸收失活。乙烯合成抑制恢复组成型铁吸收表型。我们提出 PAP/SAL 通路、乙烯信号和铁代谢之间存在联系。当在缺铁条件下生长的突变植物在叶子中喷洒铁时，它们无法使根系对铁的吸收失活。乙烯合成抑制恢复组成型铁吸收表型。我们提出 PAP/SAL 通路、乙烯信号和铁代谢之间存在联系。当在缺铁条件下生长的突变植物在叶子中喷洒铁时，它们无法使根系对铁的吸收失活。乙烯合成抑制恢复组成型铁吸收表型。我们提出 PAP/SAL 通路、乙烯信号和铁代谢之间存在联系。