UVC light-induced metabolic modifications at the level of the plant cells and tissue determined by FTIR and Raman...

This study investigates the biochemical and structural responses of Reynoutria japonica Houtt. (Japanese knotweed) to ultraviolet-C (UVC) radiation as a model abiotic stress. Using a combination of ATR-FTIR spectra, transmission FTIR, and confocal Raman microspectroscopic imaging, we provided the first multi-level, spatially resolved insight into acute stress-related metabolic alterations and modifications from tissue to cellular level. We characterized alterations in primary and secondary metabolism from tissue to the cellular level. Semi-quantitative ATR-FTIR analysis revealed stress-induced shifts in carbohydrate, protein, and lipid content, particularly in chloroplasts and photosynthetic tissues. FTIR and Raman hyperspectral imaging of leaf, stem, and root cross-sections, coupled with chemometric analyses, revealed spatial redistribution of metabolites and cell wall components, including cellulose depletion, pectin migration, and enhanced phenolic compound synthesis. These modifications occurred without anatomical damage, demonstrating strong biochemical plasticity. Our findings highlight that R. japonica employs coordinated biochemical remodelling-combining structural reinforcement, membrane lipid reorganisation, and phenolic accumulation, to preserve its functional integrity under acute UVC exposure. This multi-level insight establishes vibrational spectroscopy as a powerful diagnostic tool for studying plant adaptability to environmental stress.