title: Spatiotemporal variation of nitrate uptake kinetics within the maize (Zea mays L.) root system is associated with greater nitrate uptake and interactions with architectural phenes.
abstract: Increasing maize nitrogen acquisition efficiency is a major goal for the 21st century. Nitrate uptake kinetics (NUK) are defined by I max and K m, which denote the maximum uptake rate and the affinity of transporters, respectively. Because NUK have been studied predominantly at the molecular and whole-root system levels, little is known about the functional importance of NUK variation within root systems. A novel method was created to measure NUK of root segments that demonstrated variation in NUK among root classes (seminal, lateral, crown, and brace). I max varied among root class, plant age, and nitrate deprivation combinations, but was most affected by plant age, which increased I max, and nitrate deprivation time, which decreased I max K m was greatest for crown roots. The functional-structural simulation SimRoot was used for sensitivity analysis of plant growth to root segment I max and K m, as well as to test interactions of I max with root system architectural phenes. Simulated plant growth was more sensitive to I max than K m, and reached an asymptote near the maximum I max observed in the empirical studies. Increasing the I max of lateral roots had the largest effect on shoot growth. Additive effects of I max and architectural phenes on nitrate uptake were observed. Empirically, only lateral root tips aged 20 d operated at the maximum I max, and simulations demonstrated that increasing all seminal and lateral classes to this maximum rate could increase plant growth by as much as 26%. Therefore, optimizing I max for all maize root classes merits attention as a promising breeding goal.
authors.affiliation: Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA Intercollege Program in Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Larry M
authors.initials: LM
authors.lastname: York
authors.affiliation: Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA Ben-Gurion University of the Negev, J. Blaustein Institute for Desert Research/French Institute of Dryland Agricultural Biotechnology, Sede-Boqer Campus, 84990 Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Silberbush
authors.affiliation: Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA jpl4@psu.edu.
authors.forename: Jonathan P
authors.identifier: 0000-0002-7265-9790
authors.initials: JP
authors.lastname: Lynch
mesh_terms: D007700:Kinetics; D009566:Nitrates / Q000378:metabolism*; D010827:Physiology; D018521:Plant Physiological Phenomena; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*; D003313:Zea mays / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D009566:Nitrates
keywords: Acquisition; architecture; corn; depletion; nitrogen; plant; rhizosphere; soil.