Lignification and related parameters in copper-exposed Matricaria chamomilla roots: Role of H2O2 and NO in this process

▶ Dithiothreitol (H2O2 scavenger) prevented Cu-induced lignin accumulation and decreased the activities of guaiacol peroxidase, ascorbate peroxidase, cinnamyl alcohol dehydrogenase and polyphenol oxidase. ▶ Dithiothreitol elevated accumulation of total soluble phenols and phenolic acids in all three fractions investigated. ▶ The opposite trends were recorded after application of NO scavenger (PTIO). ▶ NO, in addition to H2O2, seems to be important for the regulation of PAL activity. ▶ H2O2 was found to be essential for complete lignin deposition during Cu excess.