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Keywords:

  • maize;
  • nitrate;
  • nitrogen;
  • nitrogen use efficiency (NUE);
  • uptake

Summary

  • An understanding of nitrate (inline image) uptake throughout the lifecycle of plants, and how this process responds to nitrogen (N) availability, is an important step towards the development of plants with improved nitrogen use efficiency (NUE).
  • inline image uptake capacity and transcript levels of putative high- and low-affinity inline image transporters (NRTs) were profiled across the lifecycle of dwarf maize (Zea mays) plants grown at reduced and adequate inline image.
  • Plants showed major changes in high-affinity inline image uptake capacity across the lifecycle, which varied with changing relative growth rates of roots and shoots. Transcript abundances of putative high-affinity NRTs (predominantly ZmNRT2.1 and ZmNRT2.2) were correlated with two distinct peaks in high-affinity root inline image uptake capacity and also N availability. The reduction in inline image supply during the lifecycle led to a dramatic increase in inline image uptake capacity, which preceded changes in transcript levels of NRTs, suggesting a model with short-term post-translational regulation and longer term transcriptional regulation of inline image uptake capacity.
  • These observations offer new insight into the control of inline image uptake by both plant developmental processes and N availability, and identify key control points that may be targeted by future plant improvement programmes to enhance N uptake relative to availability and/or demand.