Overexpression of OsPIN2 Regulates Root Growth and Formation in Response to Phosphate Deficiency in Rice.

Huwei Sun,Daxia Wu,Xiaoli Guo,Manman Lou,Guohua Xu,Feifei Luo,Xuhong Zhang,Fugui Xu,Yali Zhang

doi:10.3390/ijms20205144

Abstract

The response of root architecture to phosphate (P) deficiency is critical in plant growth and development. Auxin is a key regulator of plant root growth in response to P deficiency, but the underlying mechanisms are unclear. In this study, phenotypic and genetic analyses were undertaken to explore the role of OsPIN2, an auxin efflux transporter, in regulating the growth and development of rice roots under normal nutrition condition (control) and low-phosphate condition (LP). Higher expression of OsPIN2 was observed in rice plants under LP compared to the control. Meanwhile, the auxin levels of roots were increased under LP relative to control condition in wild-type (WT) plants. Compared to WT plants, two overexpression (OE) lines had higher auxin levels in the roots under control and LP. LP led to increased seminal roots (SRs) length and the root hairs (RHs) density, but decreased lateral roots (LRs) density in WT plants. However, overexpression of OsPIN2 caused a loss of sensitivity in the root response to P deficiency. The OE lines had a shorter SR length, lower LR density, and greater RH density than WT plants under control. However, the LR and RH densities in the OE lines were similar to those in WT plants under LP. Compared to WT plants, overexpression of OsPIN2 had a shorter root length through decreased root cell elongation under control and LP. Surprisingly, overexpression of OsPIN2 might increase auxin distribution in epidermis of root, resulting in greater RH formation but less LR development in OE plants than in WT plants in the control condition but levels similar of these under LP. These results suggest that higher OsPIN2 expression regulates rice root growth and development maybe by changing auxin distribution in roots under LP condition.

Highlights

Phosphorus (P) is essential nutrient for plant growth and development, and its deficiency dramatically affect crop productivity [1,2]
We evaluated the expression pattern of OsPIN2 in rice plants using the GUS reporter gene and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) in response to low-phosphate condition (LP) condition for 6 h
GUS location of OsPIN2 in root tips were more concentrated in epidermis under LP relative to control condition (Figure 1a)

Summary

Introduction

Phosphorus (P) is essential nutrient for plant growth and development, and its deficiency dramatically affect crop productivity [1,2]. The changes of plant morphology in response to P- deficiency are an important mechanism for crops to optimize growth and productivity [3,4]. The changes in root morphology that occur under condition of P deficiency are complex and vary according to the experimental conditions and plant species. A deficiency in P markedly inhibits primary root elongation in Arabidopsis [5,6]. In contrast to Arabidopsis, in other plant species such as rice (Oryza sativa L.), elongation of the PRs occurs as a typical response to P deficiency [4,8]. Lateral root (LR) formation is modulated under P deficiency in Arabidopsis and rice [9,10]. The mechanism in the regulatory cascade leading to change in root growth and formation are still not fully understood

Methods

Results

Conclusion