The opposite nitric oxide modulators do not lead to the opposite changes of metabolites under cadmium excess

Responses of common medicinal herb Matricaria chamomilla to short-term cadmium (Cd) exposure (48 h) alone or in combination with nitric oxide (NO) scavenger (PTIO) or donor (SNP) were studied. Modulators revealed expected impact on NO formation (depletion under PTIO but elevation under SNP) and confirmed anomalous impact on Cd accumulation (stimulation by both modulators). Changes of proline and free amino acids in the roots and fatty acids (mainly α-linolenic acid) in the shoots indicate rather relation to elevated Cd uptake than to altered NO formation. On the contrary, root profile of fatty acids revealed the most prominent changes in response to PTIO (elevation of monounsaturated and polyunsaturated fatty acids) which confirm that NO depletion stimulates their biosynthesis. Soluble phenols were elevated by SNP co-application in the roots while accumulation of chlorogenic acid and umbelliferone revealed clear regulation by NO (i.e. enhancement in response to SNP and depletion in response to PTIO). Data indicate that quantities of some metabolites are affected by accumulated Cd or NO formation and that the opposite NO modulators do not automatically lead to the opposite changes of plant metabolites.

Keywords: Fatty acids; Heavy metals; Oxidative stress; Phenolic metabolism.