Jämtgård S, Näsholm T, Huss-Danell K
Characteristics of amino acid uptake in barley
Plant and Soil: 2008 302:221-231
Abstract
Plants have the ability to take up organic nitrogen (N) but this has
not been thoroughly studied in agricultural plants. A critical question
is whether agricultural plants can acquire amino acids in a soil
ecosystem. The aim of this study was to characterize amino acid uptake
capacity in barley (Hordeum vulgare L.) from a mixture of amino acids at concentrations relevant to field conditions. Amino acids in soil solution under barley
were collected in microlysimeters. The recorded amino acid composition, 0–8.2 μM of l-Serine, l-Glutamic acid, Glycine, l-Arginine and l-Alanine,
was then used as a template for uptake studies in hydroponically grown
barley plants. Amino acid uptake during 2Â h was studied at initial
concentrations of 2–25 μM amino acids and recorded as amino acid
disappearance from the incubation solution, analysed with HPLC. The
uptake was verified in control experiments using several other
techniques. Uptake of all five amino acids occurred at 2 μM and below.
The concentration dependency of the uptake rate could be described by
Michaelis–Menten kinetics. The affinity constant (K
m) was in the range 19.6–33.2 μM. These K
m values are comparable to reported values for soil micro-organisms.
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