9311 allele of OsNAR2.2 enhances nitrate transport to improve rice yield and nitrogen use efficiency

Summary Improving nitrogen use efficiency (NUE) in rice is a requirement for future sustainable agricultural production. However, key factors and regulatory networks involved in NUE remain unclear. Here, QTL analysis, fine‐mapping and functional validation demonstrated that qCR4 encodes a putative high‐affinity nitrate transporter‐activating protein 2.2 (OsNAR2.2). Located in the endoplasmic reticulum (ER), OsNAR2.2 was confirmed to regulate nitrate transport from root‐to‐shoot and control panicle number, grain yield and NUE in rice. RNA‐seq and RT‐qPCR revealed that OsNAR2.2 modulates nitrogen utilization by altering the expressions of some nitrogen metabolism‐related genes and auxin signal‐related genes. Furthermore, the 9311 allele of OsNAR2.2 significantly enhanced panicle number, grain yield and NUE, which provides a potential target for rice yield and NUE improvement.