Salicylic acid and ultrasonic stress modulated gene expression and ginsenoside production in differentially affected Panax quinquefolius (L.) and Panax sikkimensis (Ban.) cell suspensions

Biomass and in vitro ginsenoside accumulation in cell suspensions of Panax quinquefolius (L.) and P. sikkimensis (Ban.) are differentially affected, under influence of salicylic acid (SA; 100 and 200 µM) and ultrasonic stress (US; 120 W US power, 15 s). SA addition to P. quinquefolius , was observed to lead to decline in biomass accumulation; however SA100 treatment for 5 days led to a 2.6-fold increase in ginsenoside production and Rg3 induction and exudation (6.4 mg/L). Marginally declined growth and ginsenoside productivity was observed on US exposure (% BI or biomass increment = 150.2, ginsenoside = 24.9 mg/L) as compared to unchallenged cultures (% BI = 157.5, ginsenoside = 27.2 mg/L). Co-application of US to SA100 and SA200 treatments for 5 days, although had no significant effect on cell biomass, however led to a further decline in ginsenoside productivity (SA100 + US = 48.6 mg/L, SA200 + US = 27.9 mg/L), when compared to cultures treated only with SA (SA100 = 70.5 mg/L, SA200 = 39.4 mg/L). On the other hand, addition of SA100 and SA200 to P. sikkimensis for 1 week led to a sharp decline in biomass and ginsenoside production, when compared to control cultures. Interestingly, growth and ginsenoside productivity was significantly improved upon co-application of US. US exposure was probably “boosting” mechanism of SA action (SA100 + US = %BI = 124.3, ginsenoside = 57.7 mg/L, SA200 + US = % BI = 135.6, ginsenoside = 102.17 mg/L), when compared to cultures treated with only SA (SA100 = % BI = 96.6, ginsenoside = 19.6 mg/L, SA200 = % BI 103.4, ginsenoside = 36.3 mg/L). In brief, SA100 was the best treatment for maximum ginsenoside productivity specially ginsenoside Rg3 from P. quinquefolius , whereas, SA200 + US was observed to be optimal for P. sikkimensis cell suspensions.