Time-resolved analyses of elemental distribution and concentration in living plants: An example using manganese toxicity in cowpea leaves
O_LIKnowledge of elemental distribution and concentration within plant tissues is crucial in the understanding of almost every process that occurs within plants. However, analytical limitations have hindered the microscopic determination of changes over time in the location and concentration of nutrients and contaminants in living plant tissues.\nC_LIO_LIWe developed a novel method using synchrotron-based micro X-ray fluorescence (-XRF) that allows for laterally-resolved, multi-element, kinetic analyses of plant leaf tissues in vivo. To test the utility of this approach, we examined changes in the accumulation of Mn in unifoliate leaves of 7-d-old cowpea (Vigna unguiculata) plants grown for 48 h at 0.2 and 30 M Mn in solution.\nC_LIO_LIRepeated -XRF scanning did not damage leaf tissues demonstrating the validity of the method. Exposure to 30 M Mn for 48 h increased the initial number of small spots of localized high Mn and their concentration rose from 40 to 670 mg Mn kg-1 fresh mass. Extension of the two-dimensional -XRF scans to a three-dimensional geometry provided further assessment of Mn localization and concentration.\nC_LIO_LIThis method shows the value of synchrotron-based -XRF analyses for time-resolved in vivo analysis of elemental dynamics in plant sciences.\nC_LI