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Author Britto, Dev T. ♦ Kronzucker, Herbert J.
Source SpringerLink
Content type Text
Publisher Springer-Verlag
File Format PDF
Copyright Year ©2001
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Plant Sciences ♦ Agriculture ♦ Ecology ♦ Forestry
Abstract Compartmental analysis with 13N was used to determine cytosolic nitrate (NO3 –) pools, and their turnover rates, in roots of intact barley (Hordeum vulgare L. cv Klondike) seedlings. Influx, efflux, flux to the vacuole and assimilation, and flux to the xylem, varied as much as 300-fold over a wide range of external NO3 – conditions. By contrast, the kinetic constant k c describing cytosolic NO3 – turnover varied by less than 4% from a mean value of 0.0407 min–1. Accordingly, cytosolic NO3 – pools varied linearly with influx. A literature survey showed that k c constancy is observed with both NO3 – and ammonium (NH4 +) fluxes in many plant species, including H. vulgare, Arabidopsis thaliana, Picea glauca, and Oryza sativa. The regulatory system implied by this phenomenon is fundamentally different from that of potassium (K+) fluxes, in which cytosolic pool size is held constant while k c varies with external K+ concentrations. We further present data showing that barley plants, grown on one steady-state concentration of NH4 +, restore k c within minutes of exposure to new, non-steady-state, NH4 + concentrations. We propose the existence of a high-fidelity mechanism governing the timing of cytosolic N turnover, and discuss its implications for attempts to improve plants biotechnologically.
ISSN 00320935
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2014-02-15
Publisher Place Berlin/Heidelberg
e-ISSN 14322048
Journal Planta
Volume Number 213
Issue Number 2
Page Count 7
Starting Page 175
Ending Page 181


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Source: SpringerLink