Heterologous Expression of Nitrate Assimilation Related-Protein DsNAR2.1/NRT3.1 Affects Uptake of Nitrate and Ammonium in Nitrogen-Starved <i>Arabidopsis</i>

• Main Authors: Hongping Ma, Junchao Zhao, Shuang Feng, Kun Qiao, Shufang Gong, Jingang Wang, Aimin Zhou
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: International Journal of Molecular Sciences
• Subjects: nitrogen; <i>DsNRT3.1</i>; heterologous expression; NO₃⁻ and NH₄⁺ uptake; seedling growth; <i>Arabidopsis</i>
• Online Access: https://www.mdpi.com/1422-0067/21/11/4027
• ISSN: 1661-6596; 1422-0067

Nitrogen (N) is an essential macronutrient for plant growth. Plants absorb and utilize N mainly in the form of nitrate (NO₃⁻) or ammonium (NH₄⁺). In this study, the nitrate transporter DsNRT3.1 (also known as the nitrate assimilation-related protein DsNAR2.1) was characterized from <i>Dianthus spiculifolius</i>. A quantitative PCR (qPCR) analysis showed that the <i>DsNRT3.1</i> expression was induced by NO₃⁻. Under N-starvation conditions, the transformed <i>Arabidopsis</i> seedlings expressing <i>DsNRT3.1</i> had longer roots and a greater fresh weight than the wild type. Subcellular localization showed that DsNRT3.1 was mainly localized to the plasma membrane in <i>Arabidopsis</i> root hair cells. Non-invasive micro-test (NMT) monitoring showed that the root hairs of N-starved transformed <i>Arabidopsis</i> seedlings had a stronger NO₃⁻ and NH₄⁺ influx than the wild-type seedlings, using with NO₃⁻ or NH₄⁺ as the sole N source; contrastingly, transformed seedlings only had a stronger NO₃⁻ influx when NO₃⁻ and NH₄⁺ were present simultaneously. In addition, the qPCR analysis showed that the expression of <i>AtNRT2</i> genes (<i>AtNRT2.1</i><i>–2.6</i>), and particularly of <i>AtNRT2.5</i>, in the transformed <i>Arabidopsis</i> differed from that in the wild type. Overall, our results suggest that the heterologous expression of <i>DsNRT3.1</i> affects seedlings’ growth by enhancing the NO₃⁻ and NH₄⁺ uptake in N-starved <i>Arabidopsis</i>. This may be related to the differential expression of <i>AtNRT2</i> genes.