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Maximizing NO_3~- 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 NO_3~- uptake capacity in developing seedlings.This study examines the physiological processes involved in root NO_3~- uptake and metabolism,to gain an understanding of how the NO_3~- uptake system responds to meet demand as maize seedlings transition from seed N use to external N capture.The concentrations of seedderived 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 NO_3~- uptake capacity increases until shoot N%stabilizes.The increase in root NO_3~- uptake capacity corresponds with a rapid rise in transcript levels of putative NO_3~- transporters,Zm NRT2.1 and Zm NRT2.2.The processes underlying the increase in root NO_3~- uptake capacity to meet N demand provide an insight into the processes controlling N uptake.
Maximizing NO_3 ~ 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 NO_3 uptake capacity in developing seedlings. This study examines the physiological processes involved in root NO_3 ~ - uptake and metabolism, to gain an understanding of how the NO_3 ~ - 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 decreasing immediately until stabilizing eight days after imbibition (DAI) .Similarly, shoot N% decreases, but does not stabilize until 12-13 DAI. What the decrease in free amino acid concentrations, root NO_3 ~ uptake capacity increases until shoot N% stabilizes. increase in root NO_3 ~ uptake capacity corresponds with a rapid rise in transcript levels of putative NO_3 ~ transporters, Zm NRT2 .1 and Zm NRT2.2.The processes underlying the increase in root NO_3 ~ - uptake capacity to meet N demand provide insight into the processes controlling N uptake.