Nitrogen (N) is essential for the growth and development of tea plants, and ammonium (NH4+) and nitrate (NO3-) are crucial N sources for tea yield and amino acid contents. However, the uptake and utilization of different N forms in tea plants are different. Reasonable N form is an important means to enhance the growth and development of tea plants. Therefore, supplying suitable N forms may be effective way to optimize N use efficiency. A hydroponic trial was conducted with 'Chuancha No.2′ (CC) and 'Emeiwenchun' (EW) tea cultivars with N form treatments: NH4+ and NO3-. The results showed that there were significant difference in the NH4+/NO3- uptake kinetics, dynamic changes in 15N abundance, enzyme activities, and related gene expression in N metabolism between CC and EW after NH4+/NO3- treatment. In CC and EW, NH4+ and NO3- uptake followed Michaelis-Menten kinetics at low N concentrations (< 1 mmol l-1), but CC exhibited a slightly higher uptake rate than EW when supplied with 2 mmol l-1 NH4+. In a 0–24 h 15N tracing experiment, CC roots accumulated 15N faster than EW under NH4+. NH4+-fed CC exhibited higher GS activities and higher expression levels of CsAMTs and genes involved in N utilization, such as CsNR, CsGS2, CsGDH1, and CsTS1, compared to EW. When NO3- was provided, EW roots accumulated more 15N than CC roots from 8 to 24 h, which could be attributed to the higher NR activities and higher expression levels of CsNRT1.5, CsNR, CsGS1.1 and CsGS1.2 than those in CC. In summary, the two tea varieties exhibited distinct characteristics of N uptake and utilization, as well as gene expression patterns under NH4+/NO3- treatments. CC demonstrated an advantage in NH4+ uptake and assimilation, while EW exhibited an advantage in NO3-.

中文翻译：

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氮形式对两个茶品种之间氮的吸收和利用以及相关基因表达的调节作用不同


氮 （N） 对茶树的生长发育至关重要，铵态氮 （NH4+） 和硝酸盐 （NO3-） 是茶叶产量和氨基酸含量的重要氮来源。然而，茶树对不同形式的 N 的吸收和利用是不同的。合理的氮型是促进茶树生长发育的重要手段。因此，提供合适的 N 形式可能是优化 N 使用效率的有效方法。对 'Chuancha No.2' （CC） 和 'Emeiwenchun' （EW） 茶品种进行了水培试验，采用 N 型处理：NH4+ 和 NO3-。结果表明，NH4+/NO3- 处理后 CC 和 EW 的 NH4+/NO3- 摄取动力学、15N 丰度动态变化、酶活性以及 N 代谢相关基因表达存在显著差异。在 CC 和 EW 中，NH4+ 和 NO3- 在低 N 浓度 （< 1 mmol l-1） 下遵循 Michaelis-Menten 动力学，但当提供 2 mmol l-1 NH4+ 时，CC 表现出略高于 EW 的摄取率。在 0–24 h 15N 示踪实验中，在 NH4+ 下，CC 根的积累速度比 EW 快 15N。与 EW 相比，NH4 + 喂养的 CC 表现出更高的 GS 活性和更高的 CsAMT 和参与氮利用的基因（如 CsNR、CsGS2、CsGDH1 和 CsTS1）的表达水平。当提供 NO3- 时，EW 根在 8 —24 h 内积累的 15N 比 CC 根多，这可能是由于 CC 具有更高的 NR 活性和更高的 CsNRT1.5 、 CsNR 、 CsGS1.1 和 CsGS1.2 表达水平。综上所述，在 NH4+/NO3- 处理下，2 个茶品种表现出不同的氮吸收和利用特征，以及基因表达模式。CC 在 NH4+ 吸收和同化方面表现出优势，而 EW 在 NO3- 方面表现出优势。