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Plant Physiol. 2016 Apr;170(4):2478-93. doi: 10.1104/pp.15.01827. Epub 2016 Feb 26.

Two bHLH Transcription Factors, bHLH34 and bHLH104, Regulate Iron Homeostasis in Arabidopsis thaliana.

Author information

1
School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China (X.L., H.Z.);Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Kunming, Yunnan 650223, China (X.L., H.Z., Q.A., G.L., D.Y.); andUniversity of the Chinese Academy of Sciences, Beijing 100049, China (Q.A.).
2
School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China (X.L., H.Z.);Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Kunming, Yunnan 650223, China (X.L., H.Z., Q.A., G.L., D.Y.); andUniversity of the Chinese Academy of Sciences, Beijing 100049, China (Q.A.) lianggang@xtbg.ac.cn ydq@xtbg.ac.cn.

Abstract

The regulation of iron (Fe) homeostasis is critical for plant survival. Although the systems responsible for the reduction, uptake, and translocation of Fe have been described, the molecular mechanism by which plants sense Fe status and coordinate the expression of Fe deficiency-responsive genes is largely unknown. Here, we report that two basic helix-loop-helix-type transcription factors, bHLH34 and bHLH104, positively regulate Fe homeostasis in Arabidopsis (Arabidopsis thaliana). Loss of function of bHLH34 and bHLH104 causes disruption of the Fe deficiency response and the reduction of Fe content, whereas overexpression plants constitutively promote the expression of Fe deficiency-responsive genes and Fe accumulation. Further analysis indicates that bHLH34 and bHLH104 directly activate the transcription of the Ib subgroup bHLH genes, bHLH38/39/100/101 Moreover, overexpression of bHLH101 partially rescues the Fe deficiency phenotypes of bhlh34bhlh104 double mutants. Further investigation suggests that bHLH34, bHLH104, and bHLH105 (IAA-LEUCINE RESISTANT3) function as homodimers or heterodimers to nonredundantly regulate Fe homeostasis. This work reveals that plants have evolved complex molecular mechanisms to regulate Fe deficiency response genes to adapt to Fe deficiency conditions.

PMID:
26921305
PMCID:
PMC4825117
DOI:
10.1104/pp.15.01827
[Indexed for MEDLINE]
Free PMC Article

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