Yuan Tingting, Zhu Chenglei, Li Guangzhu, Liu Yan, Yang Kebin, Li Zhen, Song Xinzhang, Gao Zhimin
Key Laboratory of National Forestry and Grassland Administration/Beijing for Bamboo and Rattan Science and Technology, Beijing, China.
International Center for Bamboo and Rattan, Institute of Gene Science and Industrialization for Bamboo and Rattan Resources, Beijing, China.
Front Genet. 2022 May 16;13:854346. doi: 10.3389/fgene.2022.854346. eCollection 2022.
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.
氮是植物生长发育必需的关键大量元素，其有效性对生物过程有很大影响。近几十年来，氮肥已在竹林中广泛施用；然而，竹子中氮代谢的机制尚未完全阐明。在此，我们对毛竹响应不同施氮方案的形态、生理和转录组变化进行了表征，以阐明氮代谢的调控机制。适当添加氮提高了叶片的叶绿素含量和净光合速率、幼苗根系的氮和铵含量、全株幼苗的生物量、侧根数量以及根系中参与氮代谢的酶的活性。基于根系的全转录组数据，在不同施氮条件下共鉴定出8632个差异表达的mRNA（DEG），如52个硝酸盐转运蛋白基因、6个硝酸还原酶基因、2个亚硝酸还原酶基因、2个谷氨酰胺合成酶基因、2个谷氨酸合成酶基因（GOGAT）、3个谷氨酸脱氢酶基因以及属于23个家族的431个转录因子。同时，分别鉴定出123个差异表达的miRNA（DEM）和396个差异表达的lncRNA（DEL）对氮响应。此外，还鉴定出94个参与氮代谢的DEM-DEG对和23个DEL-DEG对。最后，通过对DEG、DEM和DEL及其调控关系的联合分析，初步构建了一个氮代谢预测调控网络，其中包括17个氮代谢途径基因、15个转录因子、4个miRNA和10个lncRNA，该网络得到了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，有助于进一步对竹子进行遗传改良，以适应波动的氮环境。
