Salinity-Induced VOC Modulation and Physiological Adaptations in Adenosma indiana

Saline environments shape plant metabolism, driving ecological and biochemical adaptations. This study investigated the impact of salinity on Adenosma indiana (Indian scent-wort), a medicinal herb known for its volatile organic compounds (VOCs) and anti-inflammatory and antimicrobial properties, to elucidate its adaptive strategies. During the flowering stage, samples were collected from four saline microhabitats in Kalasin Province, Thailand. We analyzed soil properties, plant growth, photosynthetic pigments, compatible solutes (anthocyanins, proline, total sugars), and elemental concentrations (K, Na, Ca, Mg) across different tissues. Results showed that A. indiana maintained stable growth while enhancing chlorophyll and β-carotene levels under increasing salinity. GC-MS identified 47 VOCs, including 3-cyclopenten-1-one (first reported in this species) and β-bisabolene, both strongly linked to soil salinity. In low-salinity soils, leaves accumulated high sodium, inducing osmoprotectants (proline, total sugars) and VOCs (D-limonene, α-pinene, terpinolene, 1-octen-3-ol) in peltate glandular trichomes. Conversely, in high-salinity soils, lower leaf sodium levels were associated with increased β-bisabolene and β-caryophyllene production, suggesting distinct biochemical pathways. These findings reveal salinity-driven VOC modulation in A. indiana, highlighting its adaptive potential for medicinal applications in saline environments and its role as a source of salt-tolerant bioactive compounds.