Direct analysis of elemental biodistribution in pea seedlings by LA-ICP-MS, EDX and confocal microscopy: Imaging and quantification

• Quantitative imaging of four elements in thin sections of pea plant tissues by LA-ICP-MS.
• Distribution of Cd, Cu, Pb and Zn in root tissues of pea plant by EDX.
• Localization of reactive oxygen species (ROS) in cross-sections of root tips by confocal microscopy.

Qualitative and quantitative methods were developed for cadmium, lead, cooper and zinc mapping and quantification in root of pea Pisum sativum L. Plants were cultivated hydroponically in a Hoagland medium with the addition of 50 μM of: CdCl2, Pb(NO3)2, CuSO4, or ZnSO4. After 48 h, parts of roots were cut and analysed. LA-ICP-MS was used for in vivo quantitative imaging of the distribution of metals in thin sections of plant tissues. Calibration curve was obtained using standard addition method NIST SRM 1515 Apple Leaves spiked with standard and application of sulfur isotope as an internal standard. Energy Dispersive X-ray microanalysis Spectroscopy (EDX) was used in order to confirm results obtained by LA-ICP-MS and identify the exact localization of metals deposits in root tissue. In the electron-microscopic photographs we observed deposits of metals in the cell wall, cell membrane, vacuoles, cytoplasm and organelles, such as: mitochondria and peroxisomes. Formation and localization of O2− and H2O2 in cross-sections of root tips was confirmed by confocal microscopy. The presence of metals induced ROS (reactive oxygen species: O2 −, H2O2) production in areas corresponding to patterns of metals accumulation.