Effect Of Chilling On Accumulation Of Ginsenoside Rg₁ And Re In Panax Ginseng Adventitious Roots

Panax ginseng C.A.Meyer(ginseng)is a perennial medicinal herb and the king of herbs that is widely used because of its high medicinal value.Most of the pharmacological effects of ginseng are attributed to its secondary metabolites,known as ginsenosides,of which ginsenoside Rg1 and Re have many pharmacological effects such as antioxidant,antihyperglycemic,neuroprotectiion and hepatoprotection.Dammarendiol synthase(DDS)and protopanaxatriol synthase(PPTS)are the two key enzymes in the biosynthesis of ginsenoside Rg1 and Re.Adventitious root culture is one of the effective ways to obtain ginsenoside,but the content of ginsenoside Rg1 and Re in adventitious root is still low.In the present study,adventitious roots of ginseng were used as materials to study the effect of chilling on the accumulation of ginsenoside Rg1 and Re,which will lay a theoretical foundation for revealing the accumulation mechanism and large-scale production of ginsenoside Rg1 and Re.The results showed that compared to control,chilling elicited the accumulation of abscisic acid(ABA),increased the expression levels of DDS and PPTS,and promoted the accumulation of ginsenoside Rg1 and Re which was 1.45 times to that of control.The inhibition of ABA biosynthesis in chilling-exposed adventitious roots suppressed accumulation of ABA,expression levels of DDS and PPTS,and accumulation of ginsenoside Rg1 and Re;whereas exogenous addition of ABA restored accumulation of ABA,expression levels of DDS and PPTS,and accumulation of ginsenoside Rg1 and Re,indicating that ABA is involved in chilling-induced accumulation of ginsenoside Rg1 and Re.Then,the ABA concentration and treatment time were optimized to increase the content of ginsenoside Rg1 and Re in adventitious roots.The highest content(1.92 mg·g-1)and the yield(17.4 mg·L-1)of ginsenoside Rg1 and Re were obtained at 0.5 mmol·L-1 ABA treated with 6 d,which were 4.3 times and 3.7 times compared to that of the control.According to the above results,understanding the effect of chilling on the accumulation of ginsenoside Rg1 and Re in adventitious roots of ginseng will be helpful to improve the content of ginsenoside Rg1 and Re by using the accumulation rules.