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Nitrate Deficiency Reduces Cadmium and Nickel Accumulation in Chamomile Plants

Kovacik, Jozef, Klejdus, Borivoj, Stork, Frantisek, Hedbavny, Josef
Journal of agricultural and food chemistry 2011 v.59 no.9 pp. 5139–5149
Matricaria chamomilla, cadmium, caffeic acid, catechol oxidase, chamomile, chlorogenic acid, coumarins, culture media, free amino acids, nickel, nitrates, nutrients, nutrition, peroxidase, phenols, phenylalanine ammonia-lyase, reducing sugars, shoots
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.