Mild abiotic stresses improve essential oils yield and composition of Mediterranean medicinal and aromatic plants with minimal impact on plant growth: A systematic literature review

Medicinal and Aromatic Plants (MAPs) are industrially relevant crops primarily valued for their production of bioactive secondary metabolites used across the pharmaceutical, cosmetic, and food sectors, and many species also exhibit good adaptability to marginal environments. Their ability to synthesize many bioactive compounds, such as essential oils (EOs; singular: EO), underlines their strategic importance in pharmaceutical, cosmetic, flavor, and food industries. The Mediterranean Basin, home to a wide variety of MAPs, is increasingly affected by drought and land degradation due to climate change. One major challenge lies in optimizing the yield, qualitative characters and quantitative composition of plant extracts, while ensuring sustainable and resilient cropping systems. Specifically, MAPs often increase the production of active compounds under abiotic stress. Exploiting this feature represents an opportunity for enhancing both yield and composition of EOs and cultivating MAPs in marginal areas, though outcomes depend on multiple factors. This systematic review evaluates the potential of applying mild abiotic stress to enhance EO yield and composition and examines the underlying hypothesis that mild stress can stimulate their biosynthesis. We critically analyzed a total of forty-nine articles identified through Web of Science and Scopus, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Findings show that mild stress can influence EO content and profile, while maintaining plant growth and highlighting the adaptability of MAPs to Mediterranean conditions. We outlined that MAPs interact with the environment, affecting secondary metabolism and EOs production. Further research is needed to clarify the relationships between abiotic stress, compound synthesis, and environmental factors, aiming to stabilize EOs for industrial applications. Enhancing the adaptation of MAPs to marginal lands may offer sustainable solutions for climate-resilient agriculture and natural product industries. • This review synthesizes evidence on mild abiotic stresses in MAPs. • We analyzed how mild abiotic stresses affect EOs biosynthesis and plant growth. • Stress intensity, duration, and genotype drive plant growth and EOs production. • Thresholds between mild and severe stress guide sustainable MAPs cultivation.