Application of low intensity ultrasound in order to promote H2O2signaling and production of secondary metabolites in suspension-cultured parsley (Petroselinum crispum L.) cells

Collapse of cavitation bubbles and formation of free radicals are of routine consequence of ultrasound in liquid media. Generation of reactive oxygen species has been proposed to activate the cell signaling pathway in plant cell to get ready to protectfrom stress. Among different reactive oxygen species, H2O2 has a potential to act as a secondary messenger to promote subsequent defense reactions in plants and is capable of triggering changes in the plant cell which leads to a cascade of reactions, ultimately resulting in the formation and accumulation of secondary metabolites. In the present research suspension-cultured parsley cells were treated with ultrasound at 29 kHz with the power of 455 mW/cm2, for 10, 20, and 40 min. The viability of cells, PAL activity, certain flavonoids of parsley cells i.e., apigenin and quercetin and H2O2 content of the cells were assessed. According to the results, exposure of parsley cells to ultrasound increased the amount of quercetin, apigenin and PAL activity. Induction of phenyl propanoid metabolism was accompanied by increase of H2O2 production after exposure to ultrasound. The results implied a stimulatory effects of ultrasound on secondary metabolism of parsley cells which is mediated by signaling role of hydrogen peroxide.