Regulation of amino acid uptake by carbon and nitrogen in Pinus sylvestris

摘要

The simultaneous uptake of 13 different amino acids by Scots pine (Pinus sylvestris L.) was characterized and its regulation investigated after pre-treatments with a range of C and N metabolites. The uptake system exhibited a broad substrate specificity, acquiring all tested amino acids at similar uptake rates. Uptake of all tested amino acids by excised roots was linear over a time period of 150 min and exhibited pH-dependency, showing a peak at pH 4.0–5.0. Uptake was increased following pre-treatments with glucose and sucrose, while ammonium pre-treatments had a negative effect on amino acid acquisition. Pre-treatments with the important Krebs cycle intermediates oxaloacetate or 2-oxoglutarate did not result in altered amino acid uptake. It is speculated that the up-regulation of uptake may be due to an increased flow of glucose through a sensor mechanism, such as hexokinase. The regulation of transport by N and C suggests a function for amino acid uptake in the N nutrition of the plant, thus further highlighting the importance of organic nitrogen for plant N nutrition suggested by an increasing amount of research.