Improving root growth and cichoric acid derivatives production in hairy root culture of Echinacea purpurea by ultrasound treatment

An efficient ultrasound-stimulation strategy was developed for improving the hairy root growth and caffeic acid derivatives (CADs) biosynthesis in the hairy root cultures of Echinacea purpurea L. The 15-day-old hairy roots stimulated every 5 days by ultrasound for 6 min produced the highest amount of CADs after 30 days of culture among all ultrasound treatment experiments. The obvious increase of CADs production in E. purpurea hairy roots stimulated by ultrasound was related to the increase of both rolB-regulated endogenous indole-3-acetic acid biosynthesis and phenylalanine ammonium lyase (PAL) activity. These results provided a basis for understanding of improving growth and secondary metabolism in the process of hairy root culture stimulated by ultrasound.

► An efficient ultrasound-intensified strategy has been developed for improving CADs biosynthesis in E. purpurea hairy roots.
► The ultrasound-stimulated root growth was related to the increase of rolB gene expression for endogenous IAA biosynthesis.
► The ultrasound-stimulated CADs accumulation in the hairy roots was due to increasing phenylalanine ammonium lyase activity.
► The results presented new opportunities for understanding the hairy root culture process by ultrasound stimulation.