Abstract:

Nitrogen use efficiency is an important factor affecting the yield and quality of millet. It is of great significance to screen millet varieties with high nitrogen efficiency and explore the important genes controlling nitrogen use efficiency and their mechanism for improving nitrogen use efficiency of millet， reducing fertilizer use， protecting the environment and ensuring food security. By comparing phenotypic traits， nitrogen absorption capacity， it showed that nitrogen-efficient varieties had high ammonium nitrogen and nitrate nitrogen absorption capacity than nitrogen inefficient varieties. 3 nitrogen level treatments were set， 0， 3 and 6 mmol·L^-1 and after the rice seedlings at two-leaf one-stage were treated for 7 d. Taking 0 mmol·L^-1 nitrogen treatment as control， a total of 16 000 differential expression genes （DEGs） were obtained by RNA-seq. Through GO and KEGG enrichment analysis， it was found that amino acid synthesis and metabolism， defense-related metabolism， acetaldehyde acid and dicarboxylic acid metabolism， and carbon fixation of photosynthetic organisms， pyruvate metabolism， porphyrin and chlorophyll metabolism， MAPK signaling pathway-plant， amino sugar and nucleotide sugar metabolism played important roles in regulating the biological reaction of nitrogen metabolism. 3 348 transcription factors were predicted， which belonged to 46 families， among which the largest number of predicted transcription factors is the MYB-related family （189）， followed by the bHLH family （182）， the WRKY family （158）， the MYB family （156） and HB- Other families （153）. Through WGCNA analysis， the top 30 genes with K_ME values were screened， and 7 of them were annotated to genetic information. RT-qPCR results showed that the expression trends of Seita.9G488700， Seita.2G368800 and Seita.5G063300 were basically same as RNA-seq results， which mainly regulated the transportation and metabolism of glucose transporters and carbohydrates. .

Key words: millet, nitrogen efficiency, transcriptomics, nitrogen efficient genes

摘要：

氮利用效率是影响谷子产量和品质的重要因素。筛选氮高效谷子品种、挖掘控制氮利用效率的重要基因及解析其作用机制对于提高谷子氮利用效率、减少肥料使用、保护环境和保障粮食安全具有重要意义。通过比较氮高效和氮低效谷子品种在不同氮水平条件下表型性状和氮吸收能力发现，氮高效品种比低效品种具有较高的铵态氮和硝态氮吸收能力。设置3个氮素水平（0、3和6 mmol·L^-1），在谷苗两叶一心期处理7 d后，运用转录组测序（RNA-seq）技术比较不同品种在各个处理之间的差异表达基因（differentially expressed genes，DEGs）。结果表明，以0 mmol·L^-1氮处理为对照，共获得16 000个DEGs。通过GO和KEGG富集分析发现，氨基酸合成与代谢、防御相关代谢、乙醛酸和二羧酸代谢、光合生物的碳固定、丙酮酸代谢、卟啉与叶绿素代谢、MAPK信号通路-植物、氨基糖和核苷酸糖代谢在调控氮代谢生物反应过程中发挥重要作用。并预测到3 348个转录因子，分属46个家族，其中预测转录因子数量最多的是MYB-related家族（189个），其次为bHLH家族（182个）、WRKY家族（158个）、MYB家族（156个）和HB-other家族（153个）。通过WGCNA分析筛选出K_ME值排名前30位的基因，其中有7个基因被注释到基因信息。RT-qPCR结果显示，Seita.9G488700、Seita.2G368800和Seita.5G063300表达趋势与RNA-seq结果一致，主要调控糖转运蛋白和碳水化合物运输与代谢过程。说明氨基酸合成与代谢、光合生物的碳固定、乙醛酸和二羧酸代谢途径等信号通路在谷子氮高效利用方面发挥重要作用。研究结果筛选到3个与氮高效利用相关的基因，完善了谷子氮高效基因组注释信息，为氮高效基因资源的挖掘利用提供理论指导。

关键词: 谷子, 氮高效, 转录组学, 氮高效基因