Journal Article

The bHLH Transcription Factor bHLH104 Interacts with IAA-LEUCINE RESISTANT3 and Modulates Iron Homeostasis in Arabidopsis

Liu, Bing, Wang, Peng, Xiong, Feng, Wang, Hong-Bin, Feng, Dongru, Jin, Honglei, Zhang, Jie, Li, Mengshu, Liu, Jun, Wang, Jinfa

2015

Overview

Iron (Fe) is an indispensable micronutrient for plant growth and development. The regulation of Fe homeostasis in plants is complex and involves a number of transcription factors. Here, we demonstrate that a basic helix-loop-helix (bHLH) transcription factor, bHLH104, belonging to the IVc subgroup of bHLH family, acts as a key component positively regulating Fe deficiency responses. Knockout of bHLH104 in Arabidopsis thaliana greatly reduced tolerance to Fe deficiency, whereas overexpression of bHLH104 had the opposite effect and led to accumulation of excess Fe in soil-grown conditions. The activation of Fe deficiency-inducible genes was substantially suppressed by loss of bHLH104. Further investigation showed that bHLH104 interacted with another IVc subgroup bHLH protein, IAA-LEUCINE RESISTANT3 (ILR3), which also plays an important role in Fe homeostasis. Moreover, bHLH104 and ILR3 could bind directly to the promoters of lb subgroup bHLH genes and POPEYE (PYE) functioning in the regulation of Fe deficiency responses. Interestingly, genetic analysis showed that loss of bHLH104 could decrease the tolerance to Fe deficiency conferred by the lesion of BRUTUS, which encodes an E3 ligase and interacts with bHLH104. Collectively, our data support that bHLH104 and ILR3 play pivotal roles in the regulation of Fe deficiency responses via targeting Ib subgroup bHLH genes and PYE expression.

• Publisher: American Society of Plant Biologists
• Subject: Adaptation, Physiological - drug effects / Arabidopsis / Arabidopsis - drug effects / Arabidopsis - genetics / Arabidopsis - growth & development / Arabidopsis - metabolism / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arabidopsis thaliana / Basic helix loop helix transcription factors / Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - genetics / Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism / Basic Helix-Loop-Helix Transcription Factors - genetics / Basic Helix-Loop-Helix Transcription Factors - metabolism / Bleeding time / Chromatin Immunoprecipitation / Gene expression regulation / Gene Expression Regulation, Plant - drug effects / Gene Knockout Techniques / Genes / Genes, Plant / Homeostasis / Homeostasis - drug effects / Iron - deficiency / Iron - pharmacology / Leaves / Models, Biological / Mutation - genetics / Nucleotide Motifs - genetics / nutrient deficiencies / Phenotype / Phenotypes / Plant cells / Plant roots / Plant Roots - drug effects / Plant Roots - genetics / Plants / Promoter Regions, Genetic - genetics / Protein Binding - drug effects / Real-Time Polymerase Chain Reaction / Soil / transcription (genetics) / transcription factors