Nickel Uptake and its Effect on Some Nutrient Levels, Amino Acid Contents and Oxidative Status in Matricaria chamomilla Plants

The effect of nickel (Ni) excess on selected aspects of chamomile (Matricaria chamomilla L.) metabolism was studied. Water-soluble Ni represented 27%, 46%, and 47%, and the methanol-soluble fraction 54%, 70%, and 88% of total shoot Ni content after 10 days of treatments with 3, 60, and 120 μM Ni, respectively. “Intra-root” Ni content represented 72% (3 μM), 96% (60 μM), and 78% (120 μM) of total root Ni. Leaf rosettes treated with 120 μM contained 137 μg Ni g−1 DW after 10 days of treatment. The highest Ni concentration particularly affected the content of mineral nutrients (e.g., decrease of K and increase of Fe) and activity of selected antioxidative enzymes (increase of ascorbate peroxidase and guaiacol peroxidase activities). Malondialdehyde accumulation was not influenced (measured in methanol extracts). Among 17 detected free amino acids, accumulation of histidine, proline, methionine, and cysteine was most distinct in the leaf rosettes and/or roots, indicating their involvement in Ni detoxification. Lower Ni toxicity in comparison to previously tested metals is also discussed.