Regulatory Network of Ammonium and Nitrate Uptake and Utilization in Rice

Xiaoli Guo¹Ju Zhang¹Feilong Ma¹Pengxiang Li¹Yunlong Ma¹Kedong Xu^1*Ti Liu^2*

• ¹Key Laboratory of Plant Genetics and Molecular Breeding, Henan Key Laboratory of Crop Molecular Breeding and Bioreactor, Zhoukou Normal University, Zhoukou, China
• ²Henan Agricultural University, Zhengzhou, China

Nitrogen (N) plays a crucial role in various aspects of crop growth, development, yield, and quality.It is essential for processes ranging from protein synthesis and photosynthesis to crop adaptation and stress tolerance, thereby having a profound impact on crop production. Crops primarily absorb N in the forms of ammonium (NH₄⁺) and nitrate (NO3 -), with NH₄⁺ being the predominant form absorbed by flooded crops such as rice. This review focuses on rice and highlights recent significant advances in the mechanisms of N uptake and utilization, including the roles of NO3 -and NH₄⁺ transporters. Key transporters such as OsAMT1.1 and OsNRT1.1B play central roles in enhancing N uptake and improving N use efficiency (NUE). Furthermore, natural allelic variations in genes such as DNR1 and OsWRKY23 underlie the differences in NUE between indica and japonica subspecies.We also discuss the potential of multi-gene pyramiding strategies, such as OsAMT1.2×OsGS1.2× OsAS1, to synergistically improve NUE through coordinated regulation of N uptake, assimilation, and remobilization. Collectively, this review systematically summarizes the functions and regulatory mechanisms of key NUE-related genes in rice, providing valuable gene resources and a theoretical foundation for the molecular breeding of N-efficient rice varieties.