The Arabidopsis nitrate transporter NRT2.5 plays a role in nitrate acquisition and remobilization in nitrogen-starved plants
The Arabidopsis nitrate transporter NRT2.5 plays a role in nitrate acquisition and remobilization in nitrogen-starved plants
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DOI：
10.1111/tpj.12626
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发表时间：
2014-10-01
期刊：
影响因子：
7.2
通讯作者：
Krapp, Anne
中科院分区：
文献类型：
--
作者：
Lezhneva, Lina;Kiba, Takatoshi;Krapp, Anne
氮素是植物生长发育过程中重要的矿质营养元素。了解氮素饥饿时土壤中硝酸盐的吸收和分布机制是提高氮素吸收和利用效率以促进植物生长和生产力以及防止氮肥对环境和人类健康的负面影响的重要一步。在这项研究中，我们表明，拟南芥硝酸盐转运蛋白2.5（NRT2.5）是一个质膜定位的高亲和力硝酸盐转运蛋白在严重的氮饥饿下成年植物中起着至关重要的作用。NRT2.5的表达在氮饥饿下被诱导，并且NRT2.5在长期饥饿后的成年植物的芽和根中成为7个NRT2家族成员中最丰富的转录本。GUS报告基因分析表明，NRT 2.5在根毛区的根的表皮和皮层以及成熟叶片的小静脉中表达。NRT2.5表达的减少导致高亲和力硝酸盐摄取的减少，而不影响低亲和力摄取。在高亲和力硝酸盐转运蛋白突变体nrt2.4的背景下，nrt2.5突变降低了氮饥饿植物韧皮部中的硝酸盐水平，进一步比在单个nrt2.4突变体。NRT2.1，NRT2.2，NRT2.4和NRT2.5之间的多个突变体的生长分析表明，NRT2.5是必需的，以支持氮饥饿的成年植物的生长，通过确保有效的吸收硝酸盐集体与NRT2.1，NRT2.2和NRT2.4，并在硝酸盐再动员过程中参与到韧皮部的硝酸盐负荷。
Nitrogen is a key mineral nutrient playing a crucial role in plant growth and development. Understanding the mechanisms of nitrate uptake from the soil and distribution through the plant in response to nitrogen starvation is an important step on the way to improve nitrogen uptake and utilization efficiency for better growth and productivity of plants, and to prevent negative effects of nitrogen fertilizers on the environment and human health. In this study, we show that Arabidopsis NITRATE TRANSPORTER 2.5 (NRT2.5) is a plasma membrane-localized high-affinity nitrate transporter playing an essential role in adult plants under severe nitrogen starvation. NRT2.5 expression is induced under nitrogen starvation and NRT2.5 becomes the most abundant transcript amongst the seven NRT2 family members in shoots and roots of adult plants after long-term starvation. GUS reporter analyses showed that NRT2.5 is expressed in the epidermis and the cortex of roots at the root hair zone and in minor veins of mature leaves. Reduction of NRT2.5 expression resulted in a decrease in high-affinity nitrate uptake without impacting low-affinity uptake. In the background of the high-affinity nitrate transporter mutant nrt2.4, an nrt2.5 mutation reduced nitrate levels in the phloem of N-starved plants further than in the single nrt2.4 mutants. Growth analyses of multiple mutants between NRT2.1, NRT2.2, NRT2.4, and NRT2.5 revealed that NRT2.5 is required to support growth of nitrogen-starved adult plants by ensuring the efficient uptake of nitrate collectively with NRT2.1, NRT2.2 and NRT2.4 and by taking part in nitrate loading into the phloem during nitrate remobilization.