BACKGROUND Chloroplast is indispensable for plant response to environmental stresses, growth and development, whose function is regulated by different plant hormones. The chloroplast proteome is encoded by chloroplast genome and nuclear genome, which play essential roles in plant photosynthesis, metabolism and other biological processes. Ethylene response factors (ERFs) are key transcription factors in activating the ethylene signaling pathway and plant response to abiotic stress. But we know little about how ethylene regulates plastid function under drought stress condition. In this study we utilized tobacco overexpressing tomato ethylene responsive factor 1 (TERF1), an ERF transcription factor isolated from tomato, to investigate its effects on the plastid proteome under drought stress condition by method of iTRAQ technology. RESULTS Results show that TERF1 represses the genes encoding the photosynthetic apparatus at both transcriptional and translational level, but the genes involved in carbon fixation are significantly induced by TERF1. TERF1 regulates multiple retrograde signaling pathways, providing a new mechanism for regulating nuclear gene expression. TERF1 also regulates plant utilization of phosphorus (Pi) and nitrogen (N). We find that several metabolic and signaling pathways related with Pi are significantly repressed and gene expression analysis shows that TERF1 significantly represses the Pi transport from root to shoot. However, the N metabolism is upregulated by TERF1 as shown by the activation of different amino acids biosynthesis pathways due to the induction of glutamine synthetase and stabilization of nitrate reductase although the root-to-shoot N transport is also reduced. TERF1 also regulates other core metabolic pathways and secondary metabolic pathways that are important for plant growth, development and response to environmental stresses. Gene set linkage analysis was applied for the upregulated proteins by TERF1, showing some new potential for regulating plant response to drought stress by TERF1. CONCLUSIONS Our research reveals effects of ethylene signaling on plastid proteome related with two key biological processes, including photosynthesis and nutrition utilization. We also provide a new mechanism to regulate nuclear gene expression by ERF1 transcription factor through retrograde signals in chloroplast. These results can enrich our knowledge about ERF1 transcription factor and function of ethylene signaling pathway.

中文翻译：

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干旱胁迫下过量表达TERF1的烟草的叶绿体蛋白质组分析

背景技术叶绿体对于植物对环境胁迫，生长和发育的响应是必不可少的，其功能由不同的植物激素调节。叶绿体蛋白质组由叶绿体基因组和核基因组编码，它们在植物的光合作用，代谢和其他生物过程中起着至关重要的作用。乙烯反应因子（ERF）是激活乙烯信号传导途径和植物对非生物胁迫的关键转录因子。但是我们对乙烯在干旱胁迫条件下如何调节质体功能的了解甚少。在这项研究中，我们利用烟草中过量表达的番茄乙烯反应因子1（TERF1）（一种从番茄中分离出来的ERF转录因子），通过iTRAQ技术研究了干旱胁迫下它对质体蛋白质组的影响。结果结果表明，TERF1在转录和翻译水平上均抑制编码光合装置的基因，但与碳固定有关的基因被TERF1显着诱导。TERF1调节多个逆行信号通路，提供了调节核基因表达的新机制。TERF1还调节植物对磷（Pi）和氮（N）的利用。我们发现与Pi相关的几种代谢和信号传导途径均被显着抑制，基因表达分析表明TERF1显着抑制了Pi从根到芽的转运。然而，N的代谢由TERF1上调，这是由于谷氨酰胺合成酶的诱导和硝酸还原酶的稳定引起的不同氨基酸生物合成途径的激活所显示的，尽管从根到茎的N转运也减少了。TERF1还调节其他核心代谢途径和次生代谢途径，这些途径对于植物的生长，发育和对环境胁迫的响应都很重要。基因组连锁分析应用于TERF1上调的蛋白质，显示了一些新的潜力来调节TERF1对干旱胁迫的植物响应。结论我们的研究揭示了乙烯信号传导对质体蛋白质组的影响，这与两个关键的生物学过程有关，包括光合作用和营养利用。我们还提供了一种新的机制，通过叶绿体中的逆行信号通过ERF1转录因子调节核基因表达。这些结果可以丰富我们对ERF1转录因子和乙烯信号通路功能的了解。