Nitrogen as a regulator for flowering time in plant

Flowering is the transition process from vegetative to reproductive growth determined by many endogenous and exogenous factors. Nitrogen (N), as a dominant macronutrient for plant growth, can largely affect flowering time. A complex network integrates multiple environmental signals consisting of N status and photoperiod condition into internal regulation of flowering time in plants. So far, several transcription factors, kinases, N transporters and N assimilation enzymes have been identified to participate in the N-dependent regulation of flowering time. In this review, we summarize prominent mechanisms and key players that govern the N-dependent response of flowering time, and further discuss the interaction between N utilization and growth phase transitions in plants. Since the impact of N status on flowering time varies over plant species and shows large genetic diversities, we focus on current state of knowledge on regulatory pathways of N-determined flowering time in Arabidopsis and graminaceous plants, especially in rice. These understanding of the N-dependent flowering response can provide valuable inspirations and novel strategies to coordinate growth period with N availability for improving N use efficiency and crop productivity.