Knock-Down of CsNRT2.1, a Cucumber Nitrate Transporter, Reduces Nitrate Uptake, Root length, and Lateral Root Number at Low External Nitrate Concentration.

Wenqian Liu,Lihong Gao,Wenna Zhang,Yongqiang Tian,Juanqi Li,Yan Yan,Yang Li

doi:10.3389/fpls.2018.00722

Wenqian Liu, Lihong Gao + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2018.00722

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Abstract

Nitrogen (N) is a macronutrient that plays a crucial role in plant growth and development. Nitrate () is the most abundant N source in aerobic soils. Plants have evolved two adaptive mechanisms such as up-regulation of the high-affinity transport system (HATS) and alteration of the root system architecture (RSA), allowing them to cope with the temporal and spatial variation of . However, little information is available regarding the nitrate transporter in cucumber, one of the most important fruit vegetables in the world. In this study we isolated a nitrate transporter named CsNRT2.1 from cucumber. Analysis of the expression profile of the CsNRT2.1 showed that CsNRT2.1 is a high affinity nitrate transporter which mainly located in mature roots. Subcellular localization analysis revealed that CsNRT2.1 is a plasma membrane transporter. In N-starved CsNRT2.1 knock-down plants, both of the constitutive HATS (cHATS) and inducible HATS (iHATS) were impaired under low external concentration. Furthermore, the CsNRT2.1 knock-down plants showed reduced root length and lateral root numbers. Together, our results demonstrated that CsNRT2.1 played a dual role in regulating the HATS and RSA to acquire effectively under N limitation.

Highlights

Nitrogen (N) is considered to be one of the most important macro-elements limiting plant growth in most agricultural systems
Two NRT families (i.e., NRT1 and nitrate transporter 2 (NRT2)) have been identified to be involved in NO−3 uptake by roots, and the high-affinity transport system (HATS)-type NRT2 is more important for plants grown in soils with relatively low and changeable NO−3
Several NRT2 genes have been isolated in the model plant Arabidopsis, little information is available regarding cucumber, an important vegetable crop in the world (FAO, 2017)

Summary

INTRODUCTION

Nitrogen (N) is considered to be one of the most important macro-elements limiting plant growth in most agricultural systems. Previous physiological studies have demonstrated that higher plants have developed two high-affinity transport systems (HATS) for the influx of NO−3 into roots (Clarkson, 1986; Glass and Siddiqui, 1995; Crawford and Glass, 1998; Daniel-Vedele et al, 1998), including constitutive (cHATS) and NO−3 -inducible (iHATS) systems. Both HATS systems are able to take up NO−3 at low NO−3 concentration (

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RESULTS

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DISCUSSION