Arid agroecosystems face escalating threats from soil-borne pathogens and heavy metals (HMs) contamination, which jointly disrupt plant redox homeostasis, immunity, and productivity. Innovative strategies capable of simultaneously mitigating biological and chemical hazards are urgently needed. Here, we investigated a de novo redox-based approach integrating dopamine hydrochloride (DHCl) with the rhizosphere bacterium Bacillus safensis to suppress Fusarium oxysporum f. sp. lycopersici (FOL) and modulate soil–plant HMs dynamics in tomato under arid land conditions. DHCl exhibited strong concentration-dependent antifungal activity against FOL, which was markedly enhanced when combined with B. safensis. Greenhouse experiments revealed that the integrated treatment significantly reduced Fusarium wilt severity (≈22%) compared with infected controls (> 80%), while improving plant growth, photosynthetic pigments, and membrane stability. Mechanistically, the combined treatment restored redox balance by elevating antioxidant enzymes catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and phenylalanine ammonia lyase (PAL), reducing lipid peroxidation, hydrogen peroxide accumulation, and electrolyte leakage. Transcriptional profiling demonstrated coordinated activation of defense-related genes linked to salicylic acid, jasmonic acid, ethylene, and reactive oxygen species (ROS) signaling pathways. Field validation across two growing seasons confirmed consistent disease suppression, strengthened root architecture, and significant yield enhancement. Importantly, the combined treatment reshaped soil-root HMs partitioning by significantly reducing the accumulation of non-essential toxic metals in roots while maintaining the uptake of essential micronutrients. This study establishes DHCl as a multifunctional redox-active elicitor that, in synergy with B. safensis, suppresses Fusarium wilt and stabilizes HMs dynamics. This integrated strategy provides a sustainable, eco-compatible approach to safeguard tomato productivity in arid, hazard-prone agroecosystems.
Imran et al. (Fri,) studied this question.