Molecular mechanisms underlying nitrate responses in plants

Nitrate is an important source of inorganic nitrogen. Nitrate modulates many plant metabolic, physiological, and developmental processes. This minireview highlights recent findings on the intricate molecular wiring that allows plants to adapt to environmental nitrate conditions. We focus on the role of regulatory pathways and their components - transporters, receptors, second messengers, kinases, and transcription factors - in mediating plant metabolic and developmental responses to nitrate. Work is still needed to identify missing components of the nitrate signaling pathway and their interplay with known and well-characterized master regulators and to validate their molecular interactions to explain the complexity of phenotypical responses to nitrate. Understanding how plants perceive nitrate and transduce it into responses at the molecular level is crucial to optimize nitrogen-use efficiency, improve crop yield and mitigate the adverse environmental impacts of fertilizer overuse in a changing world.