Optimization of shoot cultures and bioactive compound accumulation in Rosa rugosa during acclimatization

Rosa rugosa is a medicinal, ornamental, and edible plant native to Eastern Asian countries, including Korea, Japan, and China. The aim of this study was to establish a system for biomass production and secondary metabolite accumulation during in vitro culture and acclimatization of Rosa rugosa. The highest rate of multiple shoot proliferation was achieved with $8.8{\mu}M$ benzyladenine (BA) (83.3%). However, the number of shoots (14.4 per explant) at $4.4{\mu}M$ BA was higher than that at $8.8{\mu}M$ BA. Compared to BA, a combination of thidiazuron (TDZ) and indole butyric acid (IBA) exhibited significantly lower shoot induction, with only 50.0~79.2% and 4.2~16.7% relative shoot formation, respectively. During acclimatization, shoots were sampled every week and their total phenolic contents were analyzed. Among various growth factors, fresh weight showed the most dramatic increase from the 3rd week (88.0 mg/plant) to 4th week (132.7 mg/plant). Total phenolics and flavonoids contents were the highest at $1^{st}$ week of acclimatization. Depending on developmental stages, total phenolics and flavonoids contents were higher in 1-yr-old shoots grown ex vitro than in those of older field-grown or in vitro-grown plants. Amongst different ages of field grown plants, 6-year-old plants, the oldest in this study, showed the lowest content in total phenolics.