Lobularia maritima essential oil modulates heavy-metal transporter expression and mitigates cadmium stress in durum...

Cadmium (Cd) pollution has emerged as a critical global environmental concern due to its significant toxicity, environmental persistence, and the pervasiveness of contamination. In recent years, essential oils (EOs) have been recognized as a promising, environmentally friendly substitute for traditional chemical treatments to counteract metal toxicity in plants. Moreover, these naturally derived compounds improve plant resilience when facing challenging environmental conditions. This study explores the potential of EOs extracted from the aerial tissues (flowering shoots and leaves) of the halophyte plant Lobularia maritima to alleviate Cd toxicity in durum wheat exposed for 10 days to 30 µM CdCl₂. GC-MS analysis revealed that L. maritima essential oil (LmEO) was predominantly composed of oxygenated monoterpenes (74.40%). The impact of various LmEO concentrations (2, 4, 6, and 8 ppm) on seed germination and early growth of durum wheat identified 4 ppm as the most effective. Application of LmEO (at 4 ppm) significantly enhanced seedling tolerance to Cd by promoting growth, reducing Cd accumulation in shoots by approximately 41%, and malondialdehyde content (a marker membrane damage) by 43% compared to the Cd-stressed plants. LmEO treatment also reduced oxidative stress by boosting antioxidant enzyme activity and reducing ROS accumulation. Furthermore, RT-qPCR analysis of six genes encoding heavy metal transporters in roots (TdNRAMP, TdHMA5, TdHMT1, TdZIF1, TdZIFL2, and TdZTP29) revealed that several key genes were upregulated by approximately twofold in durum wheat seedlings treated with LmEO, suggesting a potential link to improved Cd tolerance. Our findings suggest that exogenous LmEO application is associated with enhanced Cd stress resilience through reduced metal accumulation and improved antioxidant defense in durum wheat. These results indicate the potential of LmEO as a natural biostimulant to improve crop growth in contaminated soils.