Optimization of culture conditions and cultivation phase for the growth of Salvia viridis transformed roots and polyphenolic compound production

Abstract

Salvia viridis transformed root culture was studied using MS, WP or B5 media (full or half-strength macro- and microelements: 1/2MS, 1/2WP, 1/2B5) under varying light conditions to optimize growth and polyphenolic compound production. The highest levels of root growth (154.6 g/l and 13.6 g/l, respectively, fresh and dry weight) were observed for hairy roots grown in WP medium in the dark. UPLC analysis found the polyphenolic acid content in plant material to range from 20.7 to 45.9 mg/g dry weight (DW) depending on the conditions. The highest metabolite content was observed in roots grown in B5 medium under photoperiods. A time-course study of the hairy roots cultured in WP medium in the dark examined the effect of culture period on biomass and polyphenolic compound yield every 5 days over a 60-day period. More than 1 g of dry weight per flask and 47.8 mg of metabolite per g DW were produced after 30 days, at the beginning of the stationary phase. However, maximum production was only observed for four of the 10 detected compounds during this growth phase, between days 30 and 40; one of which was rosmarinic acid: the predominant compound in all extracts. Under optimal conditions, production was almost 10 times higher than that observed in the roots of field growing plants, which suggests that the selected optimized transformed root culture of S. viridis may be a good approach for valuable polyphenol production.