Nanoparticle-induced modulation of indole alkaloid biosynthesis and gene expression in Catharanthus roseus in vitro cultures

Abstract

Catharanthus roseus (L.) G. Don is a key medicinal plant producing pharmacologically important terpenoid indole alkaloids (TIAs). This study aimed to enhance the biosynthesis of three major TIAs; catharanthine (CAT), vincristine (VCR), and vinblastine (VBL) through a stepwise in vitro approach involving callus culture, hairy roots (HRs) induction via Agrobacterium rhizogenes , and elicitation with zinc oxide (ZnO) and chitosan (CH) nanoparticles (NPs) in solid and liquid media. Two HR lines (L1, derived from K599/p35SGFPGUS⁺, and L2, from disarmed K599) and stem-derived calli were treated with 50 and 100 mg/L of ZnO- and CH-NPs. Nanoparticle treatments had limited effects on callus growth, except 100 mg/L CH-NPs, which reduced biomass in solid medium. In suspension culture, 50 mg/L ZnO-NPs enhanced fresh weight, whereas CH-NPs reduced it. Among HRs, the highest biomass occurred with 100 mg/L ZnO-NPs. HPLC analysis revealed higher VCR levels in cultured tissues than in field-grown leaves. In solid-grown HRs, CAT increased with 100 mg/L CH-NPs, and VCR rose significantly with 100 mg/L of either NP type. In liquid-grown HRs, CAT increased with 100 mg/L CH-NPs, VCR with 100 mg/L ZnO-NPs, and VBL with 50 mg/L CH-NPs. In callus cultures, ZnO-NPs promoted CAT and VCR accumulation in solid media, while VCR increased in suspension cultures treated with 100 mg/L ZnO-NPs or 50 mg/L CH-NPs. Gene expression analysis confirmed NP-induced modulation of STR , DAT , PRX1 , and SLS , correlating with alkaloid accumulation. Overall, ZnO and CH nanoparticles effectively elicited TIA biosynthesis in C. roseus cultures, highlighting their potential for enhanced alkaloid production.

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