Spatial distribution of organic N in the course of Zea mays L. roots development

Despite an importance of organic N for plant growth, it is uncertain how spatial distribution of the hotspots of organic N is affected by root development. We visualized amino-N content and leucine aminopeptidase (LAP) activity in seminal and lateral roots of maize (Zea mays L.) at the 4- and 6-leaves phases. Amino-N and LAP hotspots were strongly overlapped at seminal roots and root tips of maize. The intensity of amino-N hotspots was fertilization-, growth phase- and root-specific. Amino-N content decreased in seminal root tips at the 6- versus the 4-leaves phase irrespective of fertilization levels, while it increased in seminal roots and lateral root tips under full fertilization with root growth. This suggests a potential functional differentiation of seminal and lateral root tips in the N-acquisition strategy in the course of plant growth.