The transition from a maternal to external nitrogen source in maize seedlings

Abstract
Maximising 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 stabilising eight days after imbibition (DAI). Similarly, shoot N% decreases, but does not stabilise until 12-13 DAI. Following the decrease in free amino acid concentrations, root NO3 - uptake capacity increases until shoot N% stabilises. 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.

Citation
Sabermanesh K, Holtham LR, George J, Roessner U, Boughton BA, et al. (2017) The transition from a maternal to external nitrogen source in maize seedlings. Journal of Integrative Plant Biology. Available: http://dx.doi.org/10.1111/jipb.12525.

Acknowledgements
We thank Hanne Thompson, Yuan Li, Nenah Mackenzie, Priyanka Reddy and Chia Ng for the technical assistance provided for this study. We also thank Metabolomics Australia, School of BioSciences, The University of Melbourne, for sample preparation and amino acid analysis. Ute Roessner and Berin Boughton are also grateful to Victorian Node of Metabolomics Australia, which is funded through Bioplatforms Australia Pty Ltd, a National Collaborative Research Infrastructure Strategy, 5.1 Biomolecular Platforms and informatics investment, and co-investment from the Victorian State Government and The University of Melbourne. This project was supported by the Australian Centre for Plant Functional Genomics, the Australian Research Council (LP130101055), DuPont Pioneer and the Grains Research and Development Corporation (GRS10437).

Publisher
Wiley

Journal
Journal of Integrative Plant Biology

DOI
10.1111/jipb.12525

Additional Links
http://onlinelibrary.wiley.com/doi/10.1111/jipb.12525/abstract

Permanent link to this record