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

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

doi:10.3389/fpls.2018.00722

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

Front Plant Sci. 2018 Jun 1:9:722. doi: 10.3389/fpls.2018.00722. eCollection 2018.

Authors

Yang Li¹, Juanqi Li², Yan Yan¹, Wenqian Liu¹, Wenna Zhang¹, Lihong Gao¹, Yongqiang Tian¹

Affiliations

¹ Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing, China.
² College of Horticulture, Henan Agricultural University, Zhengzhou, China.

Abstract

Nitrogen (N) is a macronutrient that plays a crucial role in plant growth and development. Nitrate ( ${NO}_{3}^{-}$ ) 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 ${NO}_{3}^{-}$ . 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 ${NO}_{3}^{-}$ 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 ${NO}_{3}^{-}$ effectively under N limitation.

Keywords: CsNRT2.1; cucumber; nitrate; root growth; transporter.