The plasticity of root architecture is crucial for plants to acclimate unfavorable environments including low nitrogen (LN) stress. How maize roots coordinate the growth of axile roots and lateral roots (LRs), as well as longitudinal and radial cell behaviours in response to LN stress remains unclear. Maize plants were cultivated hydroponically under control (4 mM nitrate) and LN (40 μM) conditions. Temporal and spatial samples were taken to analyse changes in the morphology, anatomical structure, and carbon/nitrogen (C/N) ratio in the axile and lateral roots. LN stress increased axile root elongation, reduced the number of crown roots, and decreased LR density and length. LN extended cell elongation zones and increased the mature cell length in the roots. LN reduced the cell diameter and total area of vessels and increased the amount of aerenchyma, but the number of cell layers in the crown root cortex was unchanged. The C/N ratio was higher in axile roots than in LRs. Maize roots acclimate to LN by optimizing the anatomical structure and N allocation. As a result axile root elongation is favored to efficiently find available N in the soil.
Via Christophe Jacquet, Mary Williams