Shoot-borne roots contribute to most of the nutrient uptake throughout the life cycle of maize. Compared with numerous studies with embryonic roots, detailed information on the phenotypic plasticity of shoot-borne roots in response to a heterogeneous nitrogen supply is scarce.
Yu et al. grow seedlings of maize (Zea mays) in a split-root system where nitrate supply is varied and examine the fine-scale morphological and anatomical traits of distinct root types. They find that axial and lateral roots respond differently to local high nitrate, and that the extent of morphological plasticity of lateral roots depends on the initiation time of the shoot-borne roots on which they develop. Morphological plasticity is higher on 2nd-order than on 1st-order lateral roots, suggesting that higher-order lateral root branching might be a potential target for genetic improvement in future maize breeding.