Abstract

Nitrogen (N) is an essential macronutrient and a key structural component of macromolecules in plants. N nutrients and metabolites can act as signals that impact on many aspects of plant biology. The plant life cycle involves a series of developmental phase transitions that must be tightly coordinated to external and internal cues in order to ensure plant survival and reproduction. N availability is one of the factors controlling phase changes. In this review, we integrate and summarize the known effects of N over different developmental stages in plants. Substantial advances have been made in our understanding of signalling and N-responsive gene regulatory networks. We focus on the molecular mechanisms underlying N regulation of developmental transitions and the role of putative new regulators that might link N availability to pathways controlling Arabidopsis growth and development from seed germination through the plant reproductive transition.