Putrescine-enhanced essential oil and phytochemicals in Melissa officinalis L. : a sustainable approach.

Amine-rich compounds play a pivotal role in plant metabolism, influencing growth, development, and defense mechanisms. Among these, polyamines such as putrescine have gained attention for their ability to enhance plant resilience and stimulate the biosynthesis of secondary metabolites. This study investigates the impact of foliar-applied putrescine on the essential oil yield and composition, and on the accumulation of phenolic compounds in Melissa officinalis, as well as on its antioxidant properties. Putrescine was applied at four concentrations: a control (no treatment) and three treatment levels (500 mg/L, 1000 mg/L, and 1500 mg/L) across five independent trials. Putrescine application significantly improved the phytochemical profile and antioxidant capacity of M. officinalis. The predominant essential oil constituents in treated plants were geranial (40.96%), neral (27.71%), caryophyllene oxide (6.00%), geranyl acetate (4.24%), and trans-thujone (2.78%). Notably, the 500 mg/L treatment led to a remarkable increase in phenolic content, particularly catechin, rosmarinic acid, and coumarin levels, reinforcing its potential as a natural elicitor. These findings underscore the potential of putrescine as an effective bio stimulant for enhancing both the yield and quality of medicinal and aromatic plants. By improving essential oil composition and boosting antioxidant compounds, putrescine application presents a promising strategy for optimizing the cultivation of M. officinalis. This approach offers valuable implications for the food and agricultural industries, supporting the development of high-value medicinal plants with enhanced functional properties.