J Integr Plant Biol ›› 2017, Vol. 59 ›› Issue (4): 261-274.DOI: 10.1111/jipb.12525

• Molecular Physiology • Previous Articles     Next Articles

Transition from a maternal to external nitrogen source in maize seedlings

Kasra Sabermanesh1,2, Luke R. Holtham1,2, Jessey George1,2, Ute Roessner3,4, Berin A. Boughton4, Sigrid Heuer1,2, Mark Tester1,5, Darren C. Plett1,2* and Trevor P. Garnett1,2,6   

  1. 1Australian Centre for Plant Functional Genomics, Waite Research Institute, University of Adelaide, Adelaide, SA 5064, Australia
    2School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Adelaide, SA 5064, Australia
    3Australian Centre for Plant Functional Genomics, School of BioSciences, University of Melbourne, Parkville, Vic. 3010, Australia
    4Metabolomics Australia, School of BioSciences, University of Melbourne, Vic. 3010, Australia
    5King Abdullah University of Science and Technology, Center for Desert Agriculture, Thuwal 23955-6900, Kingdom of Saudi Arabia
    6The Australian Plant Phenomics Facility, The Plant Accelerator, Waite Campus, The University of Adelaide, Adelaide, SA 5064, Australia
  • Received:2016-11-28 Accepted:2017-01-04 Published:2017-02-07
  • About author:*Correspondence: Email: Darren C. Plett (darren.plett@acpfg.com.au)

Abstract:

Maximizing NO3 uptake during seedling development is important as it has a major influence on plant growth and yield. However, little is known about the processes leading to, and involved in, the initiation of root NO3 uptake capacity in developing seedlings. This study examines the physiological processes involved in root NO3 uptake and metabolism, to gain an understanding of how the NO3 uptake system responds to meet demand as maize seedlings transition from seed N use to external N capture. The concentrations of seed-derived free amino acids within root and shoot tissues are initially high, but decrease rapidly until stabilizing eight days after imbibition (DAI). Similarly, shoot N% decreases, but does not stabilize until 12–13 DAI. Following the decrease in free amino acid concentrations, root NO3 uptake capacity increases until shoot N% stabilizes. The increase in root NO3 uptake capacity corresponds with a rapid rise in transcript levels of putative NO3 transporters, ZmNRT2.1 and ZmNRT2.2. The processes underlying the increase in root NO3 uptake capacity to meet N demand provide an insight into the processes controlling N uptake.

Root NO3 uptake capacity is regulated to meet plant nitrogen demand. To develop a model detailing it, we exploited a seedling's transition from seed nitrogen use to external nitrogen capture.

Key words: Amino acids, nitrate uptake, nitrogen use efficiency, NPF, NRT, roots, seed, seedling

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