Transition from a maternal to external nitrogen source in maize seedlings

by Kasra Sabermanesh, Luke R. Holtham, Jessey George, Ute Roessner, Berin A. Boughton, Sigrid Heuer, Mark Tester, Darren C. Plett, And Trevor P. Garnett
Year: 2017 ISSN: 1744-7909

Bibliography

Kasra Sabermanesh, Luke R. Holtham, Jessey George, Ute Roessner, Berin A. Boughton, Sigrid Heuer, Mark Tester, Darren C. Plett, and Trevor P. Garnett. Transition from a maternal to external nitrogen source in maize seedlings. Journal of Integrative Plant Biology. DOI: 10.1111/jipb.12525

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.

Keywords

Seedling Seed Roots Nitrogen use efficiency Nitrate uptake Zea mays NRT NPF Amino acids