A culture system for the stable and high-efficiency proliferation of adventitious roots of Panax notoginseng and ginsenoside accumulation

•Adventitious roots were efficiently induced from cotyledons of Panax notoginseng.•Two culture steps were used to initiate and then elongate new adventitious roots.•Culture conditions were optimized for root and ginsenoside production.•Ginsenoside Re concentration was 1.8-fold higher than in 3-year-old roots in the field.