The indica nitrate reductase gene OsNR2 allele enhances rice yield potential and nitrogen use efficiency

Abstract

AbstractTheindicaandjaponicarice (Oryza sativa) subspecies differ in nitrate (NO3−) assimilation capacity and nitrogen (N) use efficiency (NUE). Here, we show that a major component of this difference is conferred by allelic variation atOsNR2, a gene encoding a NADH/NADPH-dependent NO3−reductase (NR). Selection-driven allelic divergence has resulted in variantindicaandjaponica OsNR2alleles encoding structurally distinct OsNR2 proteins, withindicaOsNR2 exhibiting greater NR activity.Indica OsNR2also promotes NO3−uptake via feed-forward interaction withOsNRT1.1B, a gene encoding a NO3−uptake transporter. These properties enableindica OsNR2to confer increased effective tiller number, grain yield and NUE onjaponicarice, effects enhanced by interaction with an additionally introgressedindica OsNRT1.1Ballele. In consequence,indica OsNR2provides an important breeding resource for the sustainable increases injaponicarice yields necessary for future global food security.