Athap5a Regulates Iron Translocation In Iron-Deficientarabidopsis Thaliana

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 inArabidopsis thaliana. Here, we show that a Histone- or heme-associated proteins (HAP) transcription factor (TF), HAP5A, is necessary for the response to Fe deficiency inArabidopsis. Its expression was induced under Fe deficiency, and the lack ofHAP5Asignificantly 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 thehap5amutant, regardless of the Fe status. Yeast-one-hybrid and ChIP analyses suggested that HAP5A directly binds to the promoter region ofNAS1. Moreover, overexpression ofNAS1could rescue the chlorosis phenotype ofhap5ain 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-deficientArabidopsis thaliana.