Hormonal Regulation of Lateral Root Development in Arabidopsis Modulated byMIZ1and Requirement of GNOM Activity forMIZ1Function

Teppei Moriwaki,Chiaki Watanabe,Hideyuki Takahashi,Yutaka Miyazawa,Akie Kobayashi,Nobuharu Fujii,Mayumi Uchida

doi:10.1104/pp.111.186270

Teppei Moriwaki, Chiaki Watanabe + Show 5 more

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https://doi.org/10.1104/pp.111.186270

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Journal: Plant Physiology	Publication Date: Sep 22, 2011
Citations: 70	License type: CC BY 4.0

Affiliation: National Institute of Genetics

Abstract

Plant organ development is important for adaptation to a changing environment. Genetic and physiological studies have revealed that plant hormones play key roles in lateral root formation. In this study, we show that MIZU-KUSSEI1 (MIZ1), which was identified originally as a regulator of hydrotropism, functions as a novel regulator of hormonally mediated lateral root development. Overexpression of MIZ1 (MIZ1OE) in roots resulted in a reduced number of lateral roots being formed; however, this defect could be recovered with the application of auxin. Indole-3-acetic acid quantification analyses showed that free indole-3-acetic acid levels decreased in MIZ1OE roots, which indicates that alteration of auxin level is critical for the inhibition of lateral root formation in MIZ1OE plants. In addition, MIZ1 negatively regulates cytokinin sensitivity on root development. Application of cytokinin strongly induced the localization of MIZ1-green fluorescent protein to lateral root primordia, which suggests that the inhibition of lateral root development by MIZ1 occurs downstream of cytokinin signaling. Surprisingly, miz2, a weak allele of gnom, suppressed developmental defects in MIZ1OE plants. Taken together, these results suggest that MIZ1 plays a role in lateral root development by maintaining auxin levels and that its function requires GNOM activity. These data provide a molecular framework for auxin-dependent organ development in Arabidopsis (Arabidopsis thaliana).

Highlights

Plant organ development is important for adaptation to a changing environment
The MIZ1 loss-of-function mutant miz1-1 showed no defect in root system architecture, plants overexpressing MIZ1 (MIZ1OE) exhibited a short-root phenotype and drastically reduced lateral root formation (Fig. 1A)
To test that the phenotypes of MIZ1OE plants were dependent on MIZ1 mRNA abundance, we investigated the root phenotype of a more mildly overexpressed line, OE4

Summary

Introduction

Plant organ development is important for adaptation to a changing environment. Genetic and physiological studies have revealed that plant hormones play key roles in lateral root formation. It shows that MIZ1-dependent regulation of lateral root development requires GNOM activity. The MIZ1 loss-of-function mutant miz1-1 showed no defect in root system architecture, plants overexpressing MIZ1 (MIZ1OE) exhibited a short-root phenotype and drastically reduced lateral root formation (Fig. 1A).

Results

Conclusion