Copper uptake and translocation in chicory (Cichorium intybus L. cv Grasslands Puna) and tomato (Lycopersicon esculentum Mill. cv Rondy) plants grown in NFT system. II. The role of nicotianamine and histidine in xylem sap copper transport

• Published in: Plant and soil Vol. 223; no. 1-2; p. 245
• Main Authors: Liao, M T, Hedley, M J, Woolley, D J, Brooks, R R, Nichols, M A
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.08.2000
• Subjects: Amino acids; Copper; Grasslands; Nutrient concentrations; Speciation; Tomatoes; Translocation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1004843505053

The effect of rooting media Cu concentration (0.05-20 mg Cu L^sup -1^) on amino acid concentrations and copper speciation in the xylem sap of chicory and tomato plants was measured using 6 week old plants grown in a nutrient film technique system (NFT). Irrespective of the Cu concentration in the nutrient solutions, more than 99.68% and 99.74% of total Cu in tomato and chicory xylem sap was in a bound form. When exposed to high Cu concentrations in the rooting media, amino acid concentrations in the sap increased. Relative to other amino acids, the concentrations of glutamine (Gln), histidine (His), asparagine (Asn), valine (Val), nicotianamine (NA) and proline (Pro) in tomato xylem saps, and His, γ-aminobutyric acid (Gaba), glutamic acid (Glu), leucine (Leu), NA and phenylalanine (Phe) in chicory xylem saps showed the greatest increases. The data indicate that induced synthesis of some free amino acids as a specific and proportional response to Cu treatment. For a single complexation amino acid, the solution Cu^sup 2+^concentration vs pH titration curve for NA at 0.06-0.07 mM was most similar, closely followed by His at 0.5-0.6 mM, to the solution Cu^sup 2+^concentration behaviour in both tomato and chicory xylem sap. It is concluded that increased Cu concentrations in the rooting media induced selective synthesis of certain amino acid which include NA, His, Asn and Gln which have high stability constants with Cu. NA and His have the highest binding constants for Cu and the concentrations of NA and His in chicory and tomato xylem saps can account for all the bound Cu carried in the sap.[PUBLICATION ABSTRACT]