Modulation of artemisinin biosynthesis by elicitors, inhibitor, and precursor in hairy root cultures of Artemisia annua L.

Artemisinin is frequently used in the artemisinin-based combination therapy to cure drug-resistant malaria in Asian subcontinent and large swath of Africa. The hairy root system, using the Agrobacterium rhizogenes LBA 9402 strain to enhance the production of artemisinin in Artemisia annua L., is developed in our laboratory. The transgenic nature of hairy root lines and the copy number of transgene (rol B) were confirmed using polymerase chain reaction and Southern Blot analyses, respectively. The effect of different concentrations of methyl jasmonate (MeJA), fungal elicitors (Alternaria alternate, Curvularia limata, Fusarium solani, and Piriformospora indica), farnesyl pyrophosphate, and miconazole on artemisinin production in hairy root cultures were evaluated. Among all the factors used individually for their effect on artemisinin production in hairy root culture system, the maximum enhancement was achieved with P. indica (1.97 times). Increment of 2.44 times in artemisinin concentration by this system was, however, obtained by combined addition of MeJA and cell homogenate of P. indica in the culture medium. The effects of these factors on artemisinin production were positively correlated with regulatory genes of MVA, MEP, and artemisinin biosynthetic pathways, viz. hmgr, ads, cyp71av1, aldh1, dxs, dxr, and dbr2 in hairy root cultures of A. annua L.