Abstract
Plant secondary metabolites possess remarkable pharmacological properties and play a vital role in the treatment of diverse diseases. Due to their restricted biosynthesis, various strategies are required to boost their production. Although, nanotechnology offers a revolutionary technique to modulate plant metabolism, the molecular study underlaying silver nanoparticles (AgNPs) as nanoelicitors still remain poorly elucidated. In this study, AgNPs were biosynthesized using Catharanthus leaf extract and characterized by using different analytical techniques. The elicitation potential of AgNPs was evaluated in Ocimum tenuiflorum treated with five concentrations (20, 40, 60, 80, and 100 ppm). From the obtained results, 60 ppm was found the most effective concentration, that significantly elevating the accumulation of key metabolites and their associated gene expression. HPLC quantification indicated considerable enhancement in the content of both eugenol (57.89 µg/ml) and rosmarinic acid (50.40 µg/ml) in Tulsi leaves after treatment with AgNPs in comparison to the controls where the amount recorded was only 13.47 and 7.39 µg/ml, respectively. Furthermore, qRT-PCR analysis highlighted a notable increase in expression of biosynthetic pathway genes including EGS (6.40-fold), RAS (5.47-fold), CAD (4.71-fold), and 4CL (2.88-fold) in comparison to control. These experimental results establish, for the first time, a mechanistic link between AgNPs-induced nano-elicitation and expression of secondary metabolite pathways genes in O. tenuiflorum. The study thus bridges a critical knowledge gap and emphasizes the potential of green-synthesized AgNPs as efficient nanoelicitors to increase the high-value phytochemical production through nano-biotechnological approaches. GRAPHICAL ABSTRACT: Biosynthesis of AgNPs and its role as nanoelicitor to elevate secondary metabolites production in Ocimum as well as upregulation of related metabolic genes.