NRT2 family of nitrate transporters normally require a partner protein, NAR2 (nitrate assimilation related protein), to transport nitrate to a high-affinity (high affinity nitrate transport system, HATS), although its role is still not well understood. In this study, the CcNRT2.1 and CcNAR2 cDNAs from of Capsicum chinense were cloned and characterized in terms of their structure, phylogeny, and their organ-specific transcriptional regulation, and by ligh/dark cycle, N and sucrose. CcNRT2.1 (putative molecular mass 57.5 kDa) and CcNAR2 (22.66 kDa) retained the characteristic domains of NRT2 and NAR2 family, respectively. CcNRT2.1 is expressed exclusively in the root, and both western blot and protein immunolocalization, demonstrated its exclusive location in root epidermal and cortical cells. CcNAR2 is expressed mainly in the root, but also in fruits of 25 days post-anthesis (DPA). The presence of two protein bands (~60 and ~80 kDa) detected in the western blot, suggested that CcNRT2.1 monomer and CcNRT2.1/CcNAR2 heterodimer work together for nitrate transport function in roots. Both genes were induced by NO₃⁻, NH₄⁺ and glutamate, and CcNRT2.1 was induced by sucrose. The co-expression of both genes in the specific zone of the root (2–4 cm from the apex) in which the high-affinity nitrate transport occurs (evaluated by root NO₃⁻ endogenous content, extracellular pH alkalinization, and H⁺ net flux by MIFE technique), strongly supports that CcNRT2.1/CcNAR2 belong to a HATS, with a functional similarity to AtNRT2.1/AtNAR2.1 of Arabidopsis. These are the first components of a HATS characterized in the Capsicum genus.

中文翻译：

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CcNRT2.1 / CcNAR2的克隆和分子鉴定，是辣椒中公认的诱导性高亲和力硝酸盐转运系统。根源

NRT2硝酸盐转运蛋白家族通常需要伴侣蛋白NAR2（硝酸盐同化相关蛋白）将硝酸盐转运至高亲和力（高亲和力硝酸盐转运系统，HATS），尽管其作用尚不清楚。在这项研究中，辣椒的CcNRT2.1和CcNAR2 cDNAs被克隆并通过结构，系统发育，器官特异性转录调控以及轻/暗周期，N和蔗糖进行了表征。CcNRT2.1（推定分子量为57.5 kDa）和CcNAR2（22.66 kDa）分别保留了NRT2和NAR2家族的特征域。CcNRT2.1蛋白质仅在根中表达，蛋白质印迹和蛋白质免疫定位均证明其在根表皮和皮层细胞中的唯一位置。CcNAR2主要在根中表达，但在花后25天（DPA）的果实中也表达。在蛋白质印迹中检测到两个蛋白条带（〜60和〜80 kDa）的存在，表明CcNRT2.1单体和CcNRT2.1 / CcNAR2异二聚体共同作用于根中的硝酸盐转运功能。这两种基因通过诱导NO ₃ ^-，NH ₄ ⁺和谷氨酸，以及CcNRT2.1诱导蔗糖。两种基因在发生高亲和力硝酸盐转运的根的特定区域（距根尖2-4 cm）中共表达（通过根NO评估）₃ ^-内源性含量，细胞外pH碱化，和H ⁺通过MIFE技术净通量），强烈支持CcNRT2.1 / CcNAR2属于HATS，具有功能相似性到AtNRT2.1 / AtNAR2.1拟南芥。这些是以辣椒属为特征的HATS的第一部分。