Nitrate uptake by Roots - Transporters and Root Development

With the exception of legumes and a few other species (actinorhizal plants) that develop N₂^-fixing symbioses, plants acquire N from the soil in the inorganic form, as NH⁺₄ or NO^-₃. The subjects of NH⁺₄ uptake and symbiotic fixation are addressed in chapters 2 and 4, respectively. Considering that in most soils NO^-₃ is the predominant inorganic soluble N form, the uptake of this ion by higher plant roots is the main pathway for entry of N into the global food chain. NO^-₃ uptake and its subsequent reduction in plant cells consume a significant portion of C and energy. For many plant species including crops, purely ammoniacal nutrition has unfavourable effects on plant growth, partly due to the fact that NH⁺₄ is a cation while NO^-₃ is an anion (Chaillou and Lamaze 2001). This chapter will focus on the determinants of NO3- acquisition by plant roots.