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The formation of hydrogen peroxide (H2O2) and hydroxyl radicals after exposure of suspension-cultured hazel (Corylus avellana) cells to low intensity ultrasound and role of H2O2 signaling pathway in taxanes biosynthesis was investigated. Formation of reactive oxygen species was observed in the culture medium after sonication with 29 KHz continuous ultrasound at 4 mW/cm2 intensity for8–40 min. Sonication of the cells for 20 min remarkably increased the yields of three major taxanes, i.e., paclitaxel, 10-deacetyl baccatin, and baccatin III (up to 6.07, 2.76, and 1.7 mg/kg, respectively). Enhancement of lipoxygenase, phenylalanine ammonialyase, and 1-deoxy- d -xylulose-5-phosphate reductoisomerase activities was also observed in ultrasound-treated cells. The results suggest that formation of H2O2 in the extracellular medium is induced by ultrasound and might first be recognized by the membrane associated receptor which then induces taxanes production by activating the signaling pathway of the plant defense response to transmit the eliciting signal. |
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