Department of Biosciences-Plant Biology, Saarland University, Saarbrucken, Germany.
Plant Cell. 2011 May;23(5):1815-29. doi: 10.1105/tpc.111.084715. Epub 2011 May 17.
Understanding the regulation of key genes involved in plant iron acquisition is of crucial importance for breeding of micronutrient-enriched crops. The basic helix-loop-helix protein FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT), a central regulator of Fe acquisition in roots, is regulated by environmental cues and internal requirements for iron at the transcriptional and posttranscriptional levels. The plant stress hormone ethylene promotes iron acquisition, but the molecular basis for this remained unknown. Here, we demonstrate a direct molecular link between ethylene signaling and FIT. We identified ETHYLENE INSENSITIVE3 (EIN3) and ETHYLENE INSENSITIVE3-LIKE1 (EIL1) in a screen for direct FIT interaction partners and validated their physical interaction in planta. We demonstrate that the ein3 eil1 transcriptome was affected to a greater extent upon iron deficiency than normal iron compared with the wild type. Ethylene signaling by way of EIN3/EIL1 was required for full-level FIT accumulation. FIT levels were reduced upon application of aminoethoxyvinylglycine and in the ein3 eil1 background. MG132 could restore FIT levels. We propose that upon ethylene signaling, FIT is less susceptible to proteasomal degradation, presumably due to a physical interaction between FIT and EIN3/EIL1. Increased FIT abundance then leads to the high level of expression of genes required for Fe acquisition. This way, ethylene is one of the signals that triggers Fe deficiency responses at the transcriptional and posttranscriptional levels.
了解植物铁吸收相关关键基因的调控对于培育富含微量营养素的作物至关重要。碱性螺旋-环-螺旋蛋白 FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR(FIT)是根中铁吸收的核心调节剂,它在转录和转录后水平上受到环境线索和铁的内部需求的调节。植物应激激素乙烯促进铁的吸收,但这一过程的分子基础尚不清楚。在这里,我们证明了乙烯信号与 FIT 之间存在直接的分子联系。我们在筛选 FIT 直接相互作用伙伴时鉴定了 ETHYLENE INSENSITIVE3(EIN3)和 ETHYLENE INSENSITIVE3-LIKE1(EIL1),并在体内验证了它们的物理相互作用。我们证明,与野生型相比,缺铁时 ein3 eil1 转录组的变化比正常铁时更为明显。EIN3/EIL1 的乙烯信号对于 FIT 积累的完全水平是必需的。在应用氨基乙氧基乙烯基甘氨酸和 ein3 eil1 背景下,FIT 水平降低。MG132 可以恢复 FIT 水平。我们提出,在乙烯信号作用下,FIT 对蛋白酶体降解的敏感性降低,这可能是由于 FIT 和 EIN3/EIL1 之间的物理相互作用。FIT 丰度的增加继而导致铁吸收所需基因的高水平表达。这样,乙烯是触发铁缺乏反应在转录和转录后水平的信号之一。