Rice NIN-LIKE PROTEIN 1 Rapidly Responds to Nitrogen Deficiency and Improves Yield and Nitrogen Use Efficiency

Nitrogen (N) is indispensable for crop growth and yield, but excessive agricultural application of nitrogenous fertilizers has generated severe environmental problems. A desirable and economical solution to cope with these issues is to improve crop nitrogen use efficiency (NUE). Plant NUE has been a focal point of intensive research worldwide, yet much more has to be learned about its genetic determinants and regulation. Here, we show that rice NIN-LIKE PROTEIN 1 (OsNLP1) plays a fundamental role in N utilization. OsNLP1 protein localizes in nucleus and its transcript level is rapidly induced by N starvation. Overexpression of OsNLP1 improves plant growth, grain yield and NUE under different N conditions while knockout of OsNLP1 impairs grain yield and NUE under N limiting conditions. OsNLP1 regulates nitrate and ammonium utilization by cooperatively orchestrating multiple N uptake and assimilation genes. Chromatin immunoprecipitation and yeast-one-hybrid assays show that OsNLP1 can directly bind to the promoter of these genes to activate their expression. Therefore, our results demonstrate that OsNLP1 is a key regulator of N utilization and represents a potential target for improving NUE and yield in rice. One-sentence summaryOsNLP1 rapidly responds to N availability, enhances N uptake and assimilation, and holds great potential in promoting high yield in rice.