Researchers have identified a natural gene variant that improves nitrogen sensitivity and increases grain yields in modern rice cultivars, according to a study published in Nature Communications. Modern Green Revolution rice varieties generate high crop yields but require large amounts of nitrogen fertilizer and exhibit lowered nitrogen responsiveness, which reduces overall nitrogen-use efficiency.
To investigate the genetic mechanisms behind low nitrogen responsiveness, the research team conducted a genome-wide association study tracking biomass response to nitrogen across a diverse rice germplasm panel. The analysis identified the gene BRN1 as a central regulator of nitrogen-dependent biomass accumulation. The gene controls NLP3, a master transcription factor that directs plant nitrate signaling.
Under elevated nitrogen supply, the strigolactone signaling repressor protein D53 accumulates and binds to BRN1, which represses the transcription of NLP3 and weakens the plant's nitrogen response. The high-response BRN1H allele produces a more stable protein that relieves this D53-driven suppression. Breeding the BRN1H allele into modern rice cultivars significantly increased nitrogen sensitivity and boosted grain yield under both low and high nitrogen conditions.
Huwei Sun and Yake Chen contributed equally as lead authors on the paper alongside Chengcai Chu at South China Agricultural University in Guangzhou. Jiayang Li at the Chinese Academy of Sciences in Beijing supplied the d53 mutant used in the experiments, which received funding support from the National Natural Science Foundation of China and the Biological Breeding-National Science and Technology Major Project.
