Organic tea is more popular than conventional tea that originates from fertilized plants. Amino acids inorganic soils constitute a substantial pool nitrogen (N) available for plants. However, the amino-acid contents in soils of tea plantations and how tea plants take up these amino acids remain largely unknown. In this study, we show that the amino-acid content in the soil of an organic tea plantation is significantly higher than that of a conventional tea plantation. Glutamate, alanine, valine, and leucine were the most abundant amino acids in the soil of this tea plantation. When 15N-glutamate was fed to tea plants, it was efficiently absorbed and significantly increased the contents of other amino acids in the roots. We cloned seven CsLHT genes encoding amino-acid transporters and found that the expression of CsLHT1, CsLHT2, and CsLHT6 in the roots significantly increased upon glutamate feeding. Moreover, the expression of CsLHT1 or CsLHT6 in a yeast amino-acid uptake-defective mutant, 22∆10α, enabled growth on media with amino acids constituting the sole N source. Amino-acid uptake assays indicated that CsLHT1 and CsLHT6 are H+-dependent high- and low-affinity amino-acid transporters, respectively. We further demonstrated that CsLHT1 and CsLHT6 are highly expressed in the roots and are localized to the plasma membrane. Moreover, overexpression of CsLHT1 and CsLHT6 in Arabidopsis significantly improved the uptake of exogenously supplied 15N-glutamate and 15N-glutamine. Taken together, our findings are consistent with the involvement of CsLHT1 and CsLHT6 in amino-acid uptake from the soil, which is particularly important for tea plants grown inorganic tea plantations.

中文翻译：

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茶树 CsLHT1 和 CsLHT6 转运蛋白从有机茶园的土壤中吸收氨基酸作为氮源

有机茶比源自受精植物的传统茶更受欢迎。氨基酸无机土壤构成可用于植物的大量氮 (N)。然而，茶园土壤中的氨基酸含量以及茶树如何吸收这些氨基酸仍然很大程度上未知。在这项研究中，我们表明有机茶园土壤中的氨基酸含量明显高于传统茶园。谷氨酸、丙氨酸、缬氨酸和亮氨酸是该茶园土壤中最丰富的氨基酸。什么时候15将N-谷氨酸喂给茶树，它被有效吸收并显着增加了根中其他氨基酸的含量。我们克隆了七个CsLHT编码氨基酸转运蛋白的基因，发现CsLHT1,CsLHT2,和CsLHT6谷氨酸喂养后根中的含量显着增加。此外，表达CsLHT1要么CsLHT6在酵母氨基酸摄取缺陷突变体 22Δ10α 中，能够在氨基酸构成唯一 N 源的培养基上生长。氨基酸摄取测定表明 CsLHT1 和 CsLHT6 是 H+分别依赖于高亲和力和低亲和力氨基酸转运蛋白。我们进一步证明了CsLHT1和CsLHT6在根中高度表达并定位于质膜。此外，过度表达CsLHT1和CsLHT6在拟南芥显着提高了外源性供给的吸收15N-谷氨酸和15N-谷氨酰胺。综上所述，我们的研究结果与 CsLHT1 和 CsLHT6 参与土壤中氨基酸的吸收一致，这对于茶树种植的无机茶园尤为重要。