Abstract

Forest trees have access to diverse nitrogenous compounds in the soil such as ammonium, nitrate and amino acids. Recent progress has been made in the identification and characterization of ammonium and nitrate transporters. However, much more limited is our current knowledge of amino acid transport systems despite their relevance to fully understanding nitrogen nutrition in trees.In the present study, we have identified 10 genes encoding putative amino acid permeases of the AAP family in maritime pine (Pinus pinaster Ait.). Four members of this family, PpAAP1, PpAAP2, PpAAP3 and PpAAP4 were phylogenetically related to AtAAP5, involved in arginine transport in Arabidopsis thaliana. One of these genes, PpAAP1, exhibited enhanced expression levels in maritime pine roots when arginine was externally supplied. PpAAP1 was functionally characterized by complementation of a yeast mutant strain defective in the transport of arginine, allowing yeast to take up [¹⁴C]-arginine with high affinity. Furthermore, PpAAP1 was able to restore the severely affected root uptake of arginine displayed by AtAAP5 T-DNA mutants. Uptake rates of ¹⁵N-labelled arginine were significantly higher in PpAAP1-overexpressing plants when compared to wild-type and AtAAP5 mutant plants. Taken together, our results indicate that PpAAP1 is a high-affinity arginine transporter in maritime pine.

中文翻译：

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氨基酸渗透酶 PpAAP1 介导海松中的精氨酸转运

摘要

森林树木可以接触到土壤中的多种含氮化合物，例如铵、硝酸盐和氨基酸。最近在铵和硝酸盐转运蛋白的鉴定和表征方面取得了进展。然而，尽管氨基酸转运系统与充分了解树木中的氮营养相关，但我们目前对氨基酸转运系统的了解更为有限。在本研究中，我们已经确定了 10 个编码海松 ( Pinus pinaster ) 中 AAP 家族氨基酸通透酶的基因。哎呀。）。该家族的四个成员，PpAAP1、PpAAP2、PpAAP3 和 PpAAP4 在系统发育上与 AtAAP5 相关，参与拟南芥中的精氨酸转运。这些基因之一，PpAAP1，当外部供应精氨酸时，在海松根中表现出增强的表达水平。PpAAP1的功能特征在于与精氨酸转运缺陷的酵母突变株互补，使酵母以高亲和力吸收[ ^{14 C]-精氨酸。}此外，PpAAP1 能够恢复 AtAAP5 T-DNA 突变体显示的严重影响的精氨酸根吸收。与野生型和 AtAAP5 突变植物相比，过表达PpAAP1 的植物中¹⁵ N 标记的精氨酸的摄取率显着更高。总之，我们的结果表明 PpAAP1 是海松中的高亲和力精氨酸转运蛋白。