State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
J Integr Plant Biol. 2020 Dec;62(12):1910-1925. doi: 10.1111/jipb.12984. Epub 2020 Jul 20.
Iron (Fe) deficient plants employ multiple strategies to increase root uptake and root-to-shoot translocation of Fe. The identification of genes that are responsible for these processes, and a comprehensive understanding of the regulatory effects of transcriptional networks on their expression, including transcription factors (TFs), is underway in Arabidopsis thaliana. Here, we show that a Histone- or heme-associated proteins (HAP) transcription factor (TF), HAP5A, is necessary for the response to Fe deficiency in Arabidopsis. Its expression was induced under Fe deficiency, and the lack of HAP5A significantly decreased Fe translocation from the root to the shoot, resulting in substantial chlorosis of the newly expanded leaves, compared with the wild-type (WT, Col-0). Further analysis found that the expression of a gene encoding nicotianamine (NA) synthase (NAS1) was dramatically decreased in the hap5a mutant, regardless of the Fe status. Yeast-one-hybrid and ChIP analyses suggested that HAP5A directly binds to the promoter region of NAS1. Moreover, overexpression of NAS1 could rescue the chlorosis phenotype of hap5a in Fe deficient conditions. In summary, a novel pathway was elucidated, showing that NAS1-dependent translocation of Fe from the root to the shoot is controlled by HAP5A in Fe-deficient Arabidopsis thaliana.
缺铁植物采用多种策略来增加根部对铁的吸收和根到梢的铁转运。在拟南芥中，鉴定负责这些过程的基因，并全面了解转录网络对其表达的调控作用，包括转录因子（TFs），正在进行中。在这里，我们表明，组蛋白或血红素相关蛋白（HAP）转录因子（TF）HAP5A 是拟南芥对铁缺乏响应所必需的。其表达在缺铁条件下被诱导，并且缺乏 HAP5A 会显著降低铁从根部向梢部的转运，导致新扩展叶片出现明显的黄化，与野生型（WT，Col-0）相比。进一步分析发现，编码烟碱酸合成酶（NAS1）的基因的表达在 hap5a 突变体中显著降低，无论铁状态如何。酵母单杂交和 ChIP 分析表明，HAP5A 直接结合到 NAS1 的启动子区域。此外，在缺铁条件下，NAS1 的过表达可以挽救 hap5a 的黄化表型。总之，阐明了一条新的途径，表明在缺铁拟南芥中，NAS1 依赖的铁从根部向梢部的转运受 HAP5A 控制。
