Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68583-0915, USA.
J Exp Bot. 2012 Oct;63(16):5903-18. doi: 10.1093/jxb/ers239. Epub 2012 Sep 7.
Iron (Fe) is an essential plant micronutrient, and its deficiency limits plant growth and development on alkaline soils. Under Fe deficiency, plant responses include up-regulation of genes involved in Fe uptake from the soil. However, little is known about shoot responses to Fe deficiency. Using microarrays to probe gene expression in Kas-1 and Tsu-1 ecotypes of Arabidopsis thaliana, and comparison with existing Col-0 data, revealed conserved rosette gene expression responses to Fe deficiency. Fe-regulated genes included known metal homeostasis-related genes, and a number of genes of unknown function. Several genes responded to Fe deficiency in both roots and rosettes. Fe deficiency led to up-regulation of Cu,Zn superoxide dismutase (SOD) genes CSD1 and CSD2, and down-regulation of FeSOD genes FSD1 and FSD2. Eight microRNAs were found to respond to Fe deficiency. Three of these (miR397a, miR398a, and miR398b/c) are known to regulate transcripts of Cu-containing proteins, and were down-regulated by Fe deficiency, suggesting that they could be involved in plant adaptation to Fe limitation. Indeed, Fe deficiency led to accumulation of Cu in rosettes, prior to any detectable decrease in Fe concentration. ccs1 mutants that lack functional Cu,ZnSOD proteins were prone to greater oxidative stress under Fe deficiency, indicating that increased Cu concentration under Fe limitation has an important role in oxidative stress prevention. The present results show that Cu accumulation, microRNA regulation, and associated differential expression of Fe and CuSOD genes are coordinated responses to Fe limitation.
铁（Fe）是植物必需的微量元素，其缺乏会限制植物在碱性土壤中的生长和发育。在缺铁的情况下，植物的反应包括上调参与从土壤中摄取铁的基因。然而，对于植物地上部分对缺铁的反应，人们知之甚少。利用微阵列探测拟南芥 Kas-1 和 Tsu-1 生态型的基因表达，并与现有的 Col-0 数据进行比较，揭示了拟南芥对缺铁的保守的莲座叶基因表达反应。受 Fe 调控的基因包括已知的金属稳态相关基因，以及许多功能未知的基因。一些基因在根和莲座叶中对 Fe 缺乏都有反应。缺铁导致 Cu、Zn 超氧化物歧化酶（SOD）基因 CSD1 和 CSD2 的上调，以及 FeSOD 基因 FSD1 和 FSD2 的下调。发现了 8 个 microRNA 对 Fe 缺乏有反应。其中 3 个（miR397a、miR398a 和 miR398b/c）已知可调节含 Cu 蛋白的转录物，并且受 Fe 缺乏的下调，这表明它们可能参与植物对 Fe 限制的适应。事实上，缺铁导致 Cu 在莲座叶中的积累，而 Fe 浓度在任何可检测到的下降之前。缺乏功能 Cu、ZnSOD 蛋白的 ccs1 突变体在缺铁时更容易受到更大的氧化应激，这表明在 Fe 限制下增加的 Cu 浓度在预防氧化应激方面起着重要作用。本研究结果表明，Cu 积累、microRNA 调控以及与 Fe 和 CuSOD 基因的差异表达相关联的是对 Fe 限制的协调反应。
