Boosted centellosides production in Gotu kola (Centella asiatica) transgenic hairy roots elicited by gold and zinc nanoparticles
Maryam Khalili Hassanabad, Mohammad Hossein Mirjalili, Mohammad Mohajeri
Abstract
Valuable triterpenoids i.e., asiaticoside , madecasoside, madecassic acid , and asiatic acid , named centellosides, are well-known active compounds of Gotu kola ( Centella asiatica ) that are interestingly considered by pharmaceutical and cosmetic industries. Centellosides are biosynthesized by the specific squalene precursor catalyzed by squalene synthase (SQS). Biosynthesis and accumulation enhancement of centellosides in both wild type (A4) and transgenic hairy roots carrying Arabidopsis thaliana SQS1 gene elicited by Zn (0, 50, 100, and 200 µg/mL) and Au (0, 1, 2, and 4 µg/mL) nanoparticles (NPs) at 24 and 72 h was aimed. The highest hairy root induction frequency (87.52 %) was obtained from the leaf samples infected with transgenic bacterial strain . The doubling time of wild type A4 hairy root line (HRL9) and SQS1HRL (HRL3) was at the 8 and 6 days of culture, and their maximum biomass was measured 35 and 28 days after culture, respectively. Fresh weight of the selected HRLs treated with different NPs levels were increased in comparison with untreated ones. The highest biomass was obtained from the HRL3 treated with 100 μg/mL of ZnNPs. The transgenic hairy root line (HRL3) produced madecassoside (0.97 mg/g) and asiaticoside (0.36 mg/g DW) 2.71 and 1.76 times higher than untreated lines, respectively. The total centellosides content was maximum in the HRL3 (1.9 mg/g DW) treated with AuNPs (2 μg/mL). This finding can be developed in the bioreactors to produce of these valuable compounds at commercial scale.