Spatial and Temporal Dynamics of Phenylpropanoid Pathway-Derived Secondary Metabolites Under Abiotic Stress.

Plants, being sessile organisms, depend on finely tuned biochemical mechanisms to cope with environmental challenges. Among these, the phenylpropanoid pathway plays a central role in the production of a diverse array of secondary metabolites. These PAL-derived secondary metabolites accumulate in distinct spatiotemporal patterns across plant organs and adjust dynamically in response to environmental cues. Such spatiotemporal dynamics, regulated by distinct mechanisms, allow plants to maintain physiological function while improving tolerance to abiotic stresses. Recent advances in spatial and temporal omics technologies, such as imaging mass spectrometry (IMS) and spatial transcriptomics (ST), have revolutionized our ability to visualize the localization of secondary metabolites in plant tissues, providing insights into stress resilience. The spatial multi-omics reveals secondary metabolite accumulation and informs on the genes driving their production at each stage of the stress response. High-resolution, advanced computational, and emerging spatial multi-omics frameworks, coupled with machine-learning algorithms for spatial data interpretation, are rapidly enhancing our ability to visualize and model dynamic stress responses. However, significant challenges, including the structural complexity of plant tissues (e.g., rigid cell walls), metabolite diversity, and long life spans, complicate the exploration of secondary metabolite accumulation. Generally, the spatiotemporal accumulation of PAL-derived secondary metabolites under abiotic stress represents a sophisticated adaptive system that optimizes defence, signaling, and growth coordination in plants, aided by regulatory mechanisms such as transcriptional regulation, hormonal signaling, and secondary metabolite transport. This fundamental understanding offers practical insights into plant improvement, enabling targeted engineering and manipulation of phenylpropanoid metabolism to enhance stress tolerance.