title: Nitrate deficiency reduces cadmium and nickel accumulation in chamomile plants.
abstract: The effect of nitrogen (nitrate) deficiency (-N) on the accumulation of cadmium (Cd) and nickel (Ni) in chamomile ( Matricaria chamomilla ) plants was studied. Elimination of N from the culture medium led to decreases in N-based compounds (free amino acids and soluble proteins) and increases in C-based compounds (reducing sugars, soluble phenols, coumarins, phenolic acids, and partially flavonoids and lignin), being considerably affected by the metal presence. Proline, a known stress-protective amino acid, decreased in all -N variants. The activity of phenylalanine ammonia-lyase was stimulated only in -N control plants, whereas the activities of polyphenol oxidase and guaiacol peroxidase were never reduced in -N variants in comparison with respective +N counterparts. Among detected phenolic acids, chlorogenic acid strongly accumulated in all N-deficient variants in the free fraction and caffeic acid in the cell wall-bound fraction. Mineral nutrients were rather affected by a given metal than by N deficiency. Shoot and total root Cd and Ni amounts decreased in -N variants. On the contrary, ammonium-fed plants exposed to N deficiency did not show similar changes in Cd and Ni contents. The present findings are discussed with respect to the role of phenols and mineral nutrition in metal uptake.
authors.affiliation: Department of Botany, Institute of Biology and Ecology, Faculty of Science, P J Šafárik University, Košice, Slovak Republic. jozkovacik@yahoo.com
authors.forename: Jozef
authors.initials: J
authors.lastname: Kovácik
authors.forename: Borivoj
authors.initials: B
authors.lastname: Klejdus
authors.forename: Frantisek
authors.initials: F
authors.lastname: Stork
authors.forename: Josef
authors.initials: J
authors.lastname: Hedbavny
mesh_terms: D002104:Cadmium / Q000378:metabolism*; D020843:Chamomile / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*
chemical_list: D009566:Nitrates; D002104:Cadmium; D009532:Nickel