Resonance Raman and EPR spectroscopy studies of untreated spring wheat leaves

Leaves are the structures in plants that have evolved primarily to absorb sunlight and to convert this energy into carbohydrates, which is the essence of the photosynthesis process. In the current study Raman and electron paramagnetic resonance (EPR) spectroscopic methods were applied to investigate the drought stress occurring in the fresh wheat leaves immediately after cutting them off from the rest of the plant. Resonance Raman microspectroscopy mapping allowed us to visualize the changes in concentrations of carotenoids, playing an important role in the photosynthetic membrane, as well as quinones and carbohydrates in the selected areas in plant tissues. EPR spectroscopy was used to detect free radicals in the leaf tissue directly. Besides these very reactive, short lifetime species (monodehydroascorbate–ascorbate radical (MDA)), the long-living semiquinone and carbohydrate radicals have been also detected.