## 4 Discussion and Conclusions  
The multifaceted roles of VTs in abiotic stress responses have increasingly positioned them as central components of plant adaptation strategies. Beyond their traditional classification as ecological signals or chemical defenses, VTs, particularly isoprene, monoterpenes (e.g., \(\alpha\)-pinene and linalool), and sesquiterpen (e.g., \(\beta\)-caryophyllene)--demonstrate clear antioxidant capabilities by directly quenching ROS and enhancing cellular antioxidant enzyme systems. These functions are essential for maintaining redox homeostasis under heat, drought, ozone, and light stress conditions. Such findings expand the current understanding of VTs as endogenous protectants that dynamically support both local cellular stability and systemic plant resilience. These stress-related functions are tightly coupled with well-characterized biosynthetic routes, namely the MVA and MEP pathways, and their regulation through transcription factors (e.g., MYC2, ERF, and WRKY), phytohormone interactions (JA, SA, and ABA), and enzymatic controls (e.g., DXS, DXR, HMGR, and TPS isoforms). The spatiotemporal flexibility of these regulatory nodes underpins the plasticity of VT biosynthesis and explains their responsiveness under compound stress environments. Given these insights, VTs offer several actionable avenues for crop improvement. Key regulators identified in this review--such as MYC2, TPSs, and DXR--are promising molecular targets for CRISPR-based editing or transgenic strategies aimed at enhancing multi-trait stress tolerance. Furthermore, selecting or engineering cultivars with enhanced capacity to emit or accumulate specific VTs may enable the development of stress-resilient genotypes with optimized redox buffering and reduced damage under extreme conditions. From a production standpoint, the capacity of VTs to act as intrinsic protectants opens up new perspectives for reducing input dependence in agriculture. Their potential as markers in breeding programs, foliar biostimulants, or bio-derived protective compounds aligns with the goals of climate-resilient and sustainable crop systems. In conclusion, volatile terpenoids constitute a highly versatile and dynamic class of secondary metabolites that integrate environmental perception, metabolic regulation, and cellular protection in plants. This review synthesized recent advances in our understanding of VT biosynthesis, transcriptional and hormonal regulation, and abiotic stress responsiveness, with a particular focus on their emerging antioxidant functions. By bridging mechanistic knowledge with translational potential, we propose that key enzymes, transcription factors, and metabolic intermediates in VT pathways represent strategic entry points for improving plant performance under environmental constraints. Continued integration of multi-omics platforms and precision breeding tools will be pivotal in transforming VT-centered stress biology into actionable innovations for agriculture, enabling the next generation of stress-resilient crops and eco-compatible plant products. Looking ahead,several critical research directions can further advance our understanding and application of volatile terpenoids in plant stress adaptation and crop improvement. First, A critical avenue for future research involves elucidating the cascade mechanisms through which hormonal crosstalk regulates terpenoid biosynthesis. This issue is particularly relevant in long-lived woody species, where the temporal and spatial specificity of hormone signaling is closely linked to the maintenance of stress resilience over extended time scales. The ability of these plants to preserve metabolic plasticity and sustain energy balance under prolonged environmental stress is essential, especially in ornamental species and perennial crops, which require durable and coordinated regulatory systems. Second, the synergistic effects of multiple abiotic stressors, such as combined heat, drought, and high light, warrant deeper exploration.