Nitrogen is a key macronutrient essential for plant growth and development, and its availability has a strong influence on biological processes. Nitrogen fertilizer has been widely applied in bamboo forests in recent decades; however, the mechanism of nitrogen metabolism in bamboo is not fully elucidated. Here, we characterized the morphological, physiological, and transcriptome changes of moso bamboo in response to different schemes for nitrogen addition to illuminate the regulation mechanism of nitrogen metabolism. The appropriate addition of nitrogen improved the chlorophyll content and Pn (net photosynthetic rate) of leaves, the nitrogen and ammonium contents of the seedling roots, the biomass of the whole seedling, the number of lateral roots, and the activity of enzymes involved in nitrogen metabolism in the roots. Based on the whole transcriptome data of the roots, a total of 8,632 differentially expressed mRNAs (DEGs) were identified under different nitrogen additions, such as 52 nitrate transporter genes, 6 nitrate reductase genes, 2 nitrite reductase genes, 2 glutamine synthase genes, 2 glutamate synthase genes (GOGAT), 3 glutamate dehydrogenase genes, and 431 TFs belonging to 23 families. Meanwhile, 123 differentially expressed miRNAs (DEMs) and 396 differentially expressed lncRNAs (DELs) were characterized as nitrogen responsive, respectively. Furthermore, 94 DEM-DEG pairs and 23 DEL-DEG pairs involved in nitrogen metabolism were identified. Finally, a predicted regulatory network of nitrogen metabolism was initially constructed, which included 17 nitrogen metabolic pathway genes, 15 TFs, 4 miRNAs, and 10 lncRNAs by conjoint analysis of DEGs, DEMs, and DELs and their regulatory relationships, which was supported by RNA-seq data and qPCR results. The lncRNA-miRNA-mRNA network provides new insights into the regulation mechanism of nitrogen metabolism in bamboo, which facilitates further genetic improvement for bamboo to adapt to the fluctuating nitrogen environment.

氮是植物生长和发育所必需的关键常量营养素，其有效性对生物过程有很大影响。近几十年来，氮肥在竹林中得到了广泛应用；然而，竹子中氮代谢的机制尚未完全阐明。在这里，我们描述了毛竹响应不同氮添加方案的形态、生理和转录组变化，以阐明氮代谢的调节机制。氮肥的适当添加提高了叶片叶绿素含量和Pn（净光合速率）、苗根的氮和铵含量、整苗的生物量、侧根的数量以及与氮有关的酶的活性。根部的新陈代谢。基于根的全转录组数据，在不同氮添加下共鉴定出8632个差异表达的mRNA（DEGs），如52个硝酸盐转运蛋白基因、6个硝酸盐还原酶基因、2个亚硝酸还原酶基因、2个谷氨酰胺合酶基因、2个谷氨酸合酶基因（GOGAT）、3个谷氨酸脱氢酶基因和23个家族的431个转录因子。同时，123 个差异表达的 miRNAs (DEMs) 和 396 个差异表达的 lncRNAs (DELs) 分别被表征为氮响应。此外，确定了 94 个 DEM-DEG 对和 23 个 DEL-DEG 对参与氮代谢。最后，初步构建了一个预测的氮代谢调控网络，通过对DEGs、DEMs、和 DEL 及其监管关系，这得到了 RNA-seq 数据和 qPCR 结果的支持。lncRNA-miRNA-mRNA网络为竹子氮代谢调控机制提供了新的见解，有助于竹子进一步遗传改良以适应波动的氮环境。