Rice transcription factors OsNIGT2/3 regulate nitrogen acquisition by repressing OsNRTs and OsAMTs under high-nitrogen conditions

Hongyang Du¹Xihan Cong¹Xinmin Ruan¹Yang Yang²Fuzhi Shi¹Yanchang Luo¹Zhixiang Luo^1*

• ¹Anhui Academy of Agricultural Sciences (CAAS), Hefei, China
• ²College of Life Sciences, Zaozhuang University, Zaozhuang, Shandong, China

Nitrogen is a crucial nutrient for crop growth, yet its utilization efficiency is generally low, leading to resource waste and serious environmental problems. Future agricultural sustainability requires improved crop NUE. In this study, we investigated the functions of the rice transcription factors OsNIGT2 and OsNIGT3 in nitrate uptake under high-nitrogen conditions. Hydroponic experiments revealed that the double gene mutants presented significantly greater dry weights, nitrogen contents, total amino acid contents, and nitrate levels than did the wild type, whereas the single mutants presented no significant differences in these parameters. These findings indicate the functional redundancy of OsNIGT2 and OsNIGT3 in regulating nitrogen uptake and assimilation.Transcriptome analysis demonstrated that OsNIGT2 and OsNIGT3 act as transcriptional repressors, negatively regulating the expression of nitrogen absorption-related genes. Furthermore, DNA affinity purification sequencing (DAP-seq) identified potential targets bound by OsNIGT2, highlighting its role in the expression of several nitrogen and phosphorus utilization-related genes.Additionally, field tests shown that OsNIGT2 and OsNIGT3 knockout promotes both grain yield and NUE. In summary, OsNIGT2 and OsNIGT3 play critical roles in regulating nitrogen use efficiency in rice by coordinating nitrogen uptake, assimilation, and signaling. This study provides potential genetic targets for improving yield and NUE in rice and other crops, laying a significant foundation for future crop improvement.