Although previous researches have greatly increased our general knowledge on plant responses to nitrogen (N) stress, a comprehensive understanding of the different responses in crop genotypes is still needed. This study evaluated 304 maize accessions for low-N tolerance under field conditions, and selected the low-N sensitive Ye478 and low-N tolerant Qi319 for further investigations. After a 5-day low-N treatment, the typical N-deficient phenotype with yellowing older leaves was observed in Ye478 but not in Qi319. After the 5-day low-N stress, 16 RNA libraries from leaf and root of Ye478 and Qi319 were generated. The differentially expressed genes (DEGs) in the root of Qi319 up-regulated by special N deficiency were mainly enriched in energy-related metabolic pathways, including tricarboxylic acid metabolic process and nicotinamide metabolic process. Consistent with yellowing older leaves only observed in Ye478, the special N deficiency-responsive DEGs related to thylakoid, chloroplast, photosynthetic membrane, and chloroplast stroma pathways were repressed by low-N stress in Ye478. A total of 216 transcription factors (TFs), including ZmNLP5, were identified as special N deficiency-responsive TFs between Qi319 and Ye478, indicating the importance of transcriptional regulation of N stress-responsive pathway in different tolerance to low-N stress between crop genotypes. In addition, 15 miRNAs were identified as DEGs between Qi319 and Ye478. Taken together, this study contributes to the understanding of the genetic variations and molecular basis of low-N tolerance in maize.

尽管之前的研究大大增加了我们对植物对氮 (N) 胁迫反应的一般知识，但仍需要全面了解作物基因型的不同反应。本研究评估了 304 个玉米种质在田间条件下的低氮耐受性，并选择了低氮敏感的 Ye478 和低氮耐受的 Qi319 进行进一步调查。经过 5 天的低氮处理后，在 Ye478 中观察到典型的缺氮表型，老叶变黄，但在 Qi319 中未观察到。经过5天的低氮胁迫，Ye478和Qi319的叶和根产生了16个RNA文库。Qi319 根中差异表达基因 (DEGs) 被特殊 N 缺乏上调，主要富集在能量相关的代谢途径中，包括三羧酸代谢过程和烟酰胺代谢过程。与仅在 Ye478 中观察到的变黄老叶一致，与类囊体、叶绿体、光合膜和叶绿体基质途径相关的特殊 N 缺乏响应性 DEG 在 Ye478 中被低氮胁迫抑制。共有 216 个转录因子 (TF)，包括ZmNLP5被鉴定为 Qi319 和 Ye478 之间的特殊 N 缺乏响应 TF，表明 N 应激响应途径的转录调控在作物基因型之间对低氮胁迫的不同耐受性中的重要性。此外，有 15 个 miRNA 被鉴定为 Qi319 和 Ye478 之间的 DEG。总之，本研究有助于了解玉米耐低氮的遗传变异和分子基础。