Author(s): Mohanad Mohammed Mahmood Almuhairi

Abstract: Abiotic stresses like drought, salinity, and heat pose significant threats to medicinal plant productivity and phytochemical quality, this study investigated the morphological, physiological, biochemical, and gene expression responses of a medicinal plant to varying intensities of drought, salinity ([NaCl]), and heat stress, and evaluated the ameliorative potential of salicylic acid (SA) and gibberellic acid (GA₃), differences between two geographical origins (Shuwan and Huwayjah) were also assessed. All stress factors significantly (p<0.001) reduced growth parameters (stem height, dry weight, leaf area) and photosynthetic efficiency, while increasing oxidative stress markers (MDA, H₂O₂), plants responded by upregulating antioxidant enzymes (SOD, CAT, POD) and accumulating secondary metabolites, including essential oil components (e.g., linalool, camphor), total phenolics, flavonoids (e.g., rosmarinic acid), coriandrin, and ursolic acid. Gene expression analysis revealed upregulation of key genes in the MEP (DXR, HDR) and phenylpropanoid (PAL, CHS) pathways, sA application (15-20% mitigation) effectively alleviated stress impacts, reducing oxidative damage by up to 40% and enhancing antioxidant enzyme activity, notably, SA combined with moderate salinity increased essential oil yield by 20% and provided the highest economic return ($915/ha). GA₃ promoted stem elongation but reduced root mass, the Shuwan origin exhibited significantly higher stress tolerance (e.g., 25% higher salt tolerance) compared to Huwayjah, correlating with more favorable native soil and climatic conditions, extracts from SA-treated, drought-stressed plants showed enhanced antimicrobial and antioxidant activities, these findings highlight SA's potential for improving stress resilience and phytochemical value in medicinal plants, and underscore the importance of ecotype selection for cultivation in stress-prone environments.

DOI: 10.22271/27889289.2025.v5.i2c.208

Pages: 192-205 | Views: 31 | Downloads: 13

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