Morphological, physiological, and menthol biosynthesis genes' expression responses in peppermint (Mentha piperita L.) under the influence of copper oxide nanoparticles

Given the importance of the medicinal plant peppermint and the antimicrobial and anti-inflammatory properties of menthol, as well as considering the capability of copper oxide (CuO) nanoparticle elicitors in inducing physiobiological responses, this study was conducted at Payam Noor University, Tehran in ۲۰۲۵ to explore the effects of CuO nanoparticles (NPs) treatment on peppermint traits in a completely randomized design with ۳ repeats in the greenhouse. The first foliar application of CuO NPs at concentrations of ۵, ۱۰, and ۲۰ mg/L was performed on peppermint approximately four months after stolon planting, and the second foliar application was conducted one month after the first application. The concentration of ۵ mg/L increased plant height, fresh weight, and dry weight, whereas ۱۰ and ۲۰ mg/L led to a decrease in these traits. All nanoparticle concentrations had a negative effect on chlorophyll, causing a reduction in this pigment. In contrast, carotenoid, protein, and ascorbate peroxidase (APX) enzyme activity increased with rising nanoparticle concentrations, exhibiting a concentration-dependent response. Regarding anthocyanin, catalase, and superoxide dismutase (SOD), the ۵ mg/L concentration had no significant effect on these traits, while ۱۰ and ۲۰ mg/L concentrations increased them. Essential oil percentage and the expression of LS and MFS genes were also only affected at concentrations of ۱۰ and ۲۰ mg/L. Overall, the response of traits to CuO NPs was dependent on both nanoparticle concentration and the type of trait. Increasing the concentration of CuO NPs induced oxidative stress and activated both enzymatic and non-enzymatic antioxidant systems. Concurrent with this response, the essential oil percentage and the expression of menthol biosynthesis genes increased as metabolites. Therefore, a concentration of ۵ mg/L of CuO NPs is recommended for inducing positive growth responses in peppermint plants.

کلیدواژه ها:

Elicitor ، Essential oil ، Medicinal plants ، Secondary metabolite ، الیسیتور ، اسانس ، گیاهان دارویی ، متابولیت ثانویه