Transcription Factor WRKY33 Mediates the Phosphate Deficiency-Induced Remodeling of Root Architecture by Modulating Iron Homeostasis in Arabidopsis Roots.

Nuo Shen,Sifan Hou,Yanping Jing,Wenzhi Lan,Guoqing Tu

doi:10.3390/ijms22179275

Abstract

The remodeling of root architecture is regarded as a major development to improve the plant’s adaptivity to phosphate (Pi)-deficient conditions. The WRKY transcription factors family has been reported to regulate the Pi-deficiency-induced systemic responses by affecting Pi absorption or transportation. Whether these transcription factors act as a regulator to mediate the Pi-deficiency-induced remodeling of root architecture, a typical local response, is still unclear. Here, we identified an Arabidopsis transcription factor, WRKY33, that acted as a negative regulator to mediate the Pi-deficiency-induced remodeling of root architecture. The disruption of WRKY33 in wrky33-2 mutant increased the plant’s low Pi sensitivity by further inhibiting the primary root growth and promoting the formation of root hair. Furthermore, we revealed that WRKY33 negatively regulated the remodeling of root architecture by controlling the transcriptional expression of ALMT1 under Pi-deficient conditions, which further mediated the Fe3+ accumulation in root tips to inhibit the root growth. In conclusion, this study demonstrates a previously unrecognized signaling crosstalk between WRKY33 and the ALMT1-mediated malate transport system to regulate the Pi deficiency responses.

Highlights

Phosphorus (P) is an essential macronutrient required for constitution of several biomolecules and for regulation of biological and metabolic processes in plants [1]
We revealed that Arabidopsis WRKY33 acted as a negative regulator to mediate the Pi deficiency-induced remodeling of root system architecture (RSA), including to inhibit the primary root growth and to enhance the root hair density and length
The WRKY33 transcription factor belongs to the WRKY superfamily and plays an important role to regulate the biotic and abiotic stress in Arabidopsis [33,34,35]

Summary

Introduction

Phosphorus (P) is an essential macronutrient required for constitution of several biomolecules and for regulation of biological and metabolic processes in plants [1]. The phosphorus is acquired by plants in the form of inorganic phosphate (Pi) [2]. Pi exists at low available concentrations (typically around 1–10 μM in the soil solution) due to its ability to form insoluble complexes with cations, especially with aluminum and iron under acidic conditions and with calcium under alkaline conditions [2,3,4]. Phosphate deficiency triggers a series of Pi starvation responses (PSRs) in plants to reduce the phosphorus usage and increase the phosphorus uptake and recycling [7,8,9,10,11].

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Conclusion