# Nanoparticles Enhance In Vitro Micropropagation and Secondary Metabolite Accumulation in Origanum petraeum

## TL;DR

This study shows that silver and copper nanoparticles can boost the growth and essential oil production in Origanum petraeum, a medicinal plant from Jordan.

## Contribution

The first study to demonstrate nanoparticle-assisted growth and secondary metabolite enhancement in Origanum petraeum.

## Key findings

- AgNPs at 100 mg/L increased microshoot number and height in vitro.
- CuNPs at 50 mg/L enhanced monoterpenes like α-terpinyl acetate and geranyl acetate.
- Nanoparticles altered nutrient composition and volatile profiles in microshoots.

## Abstract

Origanum petraeum Danin, an endemic medicinal shrub from Jordan, belongs to the Lamiaceae family and possesses significant pharmaceutical potential, yet its secondary metabolite profile remains largely unexplored. This study evaluated the effects of two types of nanoparticles, silver (Ag) and copper (Cu), on in vitro propagation and secondary metabolite composition in O. petraeum microshoots. Sterilized buds were used to initiate in vitro cultures on Murashige and Skoog (MS) medium supplemented with gibberellic acid (GA3) at 0.5 mg/L. Microshoots were treated with nanoparticles at concentrations of 0, 25, 50, 100, and 150 mg/L. AgNPs at 100 mg/L promoted growth, increasing the number of microshoots to 11.6 and shoot height to 9.22 cm. Transmission electron microscopy confirmed nanoparticle uptake and translocation, with AgNPs observed in root cells as small particles (≤24.63 nm), while CuNPs formed aggregates in leaves (47.71 nm). GC-MS analysis revealed that nanoparticles altered the volatile composition; 50 mg/L CuNPs enhanced monoterpenes, including α-terpinyl acetate (29.23%) and geranyl acetate (12.76%), whereas 50 mg/L AgNPs increased sesquiterpenes, such as caryophyllene oxide (28.45%). Control in vitro cultures without nanoparticles showed simpler profiles dominated by caryophyllene oxide, while wild plants contained both monoterpenes and sesquiterpenes, with eudesm-7(11)-en-4-ol (25.10%) as the major compound. Nutrient analysis indicated that nanoparticles influenced nutrient composition in microshoots. This study is the first to report nanoparticle-assisted growth and essential oil composition in O. petraeum, demonstrating their potential to enhance growth and secondary metabolite production for pharmacological and biotechnological applications.