Nitrogen (N) is the most important essential nutrient in soils and its reduced availability can limit plant growth and development in natural ecosystems as well as in agriculture. In some areas, N is the nutrient most often deficient for crop production. However, when N inputs to the soil system exceed crop needs, there is a possibility that excessive amounts of nitrate (NO3-) may enter either ground or surface water causing serious water pollution. Plants take up N from the soil through their root system and the way the root system is build can importantly contribute to the efficiency of N uptake. To perceive the external fluctuating availability of both N concentrations and forms, plants have developed complex regulatory transcriptional networks to adapt their root system architecture. These networks are up to present not well understood. Recently, a research collaboration between UGent and Nanjing Agricultural University resulted in the discovery of the “root clock”, a mechanism that patterns lateral roots along the primary axis in the plant model Arabidopsis. This root clock may represent a general mechanism in plants to coordinate primary root growth with root branching in order to optimize the uptake of nutrients from the soil. To access this hypothesis, the role of the root clock in response to nitrogen and the underlying molecular mechanism will be investigated in a joint project carried out by a team at UGent (Belgium) and NJAU (China) using the crop model rice.