Enhanced production of bioactive plumbagin in hairy root cultures and adventitious root cultures of Plumbago zeylanica L. by a novel apocarotenoid elicitor, α-ionone

Abstract

Plumbagin, a medicinally important secondary metabolite is produced in the roots of Plumbago zeylanica Linn. Natural harvest of plumbagin from roots is a destructive process that destroys the entire plant. The aim of this study was the in vitro production of plumbagin at high concentrations. For this purpose, hairy root cultures (HRCs) and adventitious root cultures (ARCs) were induced from P. zeylanica leaf explants. Additionally, first-time α-ionone was used as an elicitor to trigger plumbagin biosynthesis. HRCs were developed using the two different strains of Agrobacterium rhizogenes (LBA1334, and R1000). R1000 strain showed the highest HR induction efficiency. ARCs were induced from the leaf explants growing in Murashige and Skoog (MS) solid media supplemented with 1 mg/L indole-3-butyric acid. Newly emerged adventitious roots were used to develop root suspension cultures in a liquid MS medium. Plumbagin content was determined by HPLC/DAD. Both HRCs and ARCs showed fast growth kinetics. The greatest increase in the production of plumbagin was achieved with 10 µM α-ionone. As compared to untreated controls, the optimum α-ionone dose resulted in a 3.6-fold and 3.1-fold increase in plumbagin in HRCs, and ARCs, respectively. These results support that α-ionone elicitor-treated HRCs and ARCs are promising technology for improved production of plumbagin to meet commercial demand.