Single cell ICP-MS as a powerful analytical tool to determine metal content in individual pollen grains

Abstract

The acquisition and storage of essential metals (Fe, Cu, Zn, Mn…) is considered to be crucial for the quality of pollen grains. It is therefore strategic to develop analytical approaches to study metal homeostasis in pollen grains that are constituted of a single cell. In this work, the coupling of a single cell introduction system with a multiquadrupole ICP MS allowed the development of a method for the analysis of Fe and Mn using the mass shift mode with oxygen or direct analysis, respectively. The method was applied for the analysis of pollen collected from wild type Arabidopsis thaliana plants grown in standard conditions and Fe- or Mn-supplemented conditions. This analytical strategy offered, as main advantages over classical bulk ICP MS approach: the analysis of extremely low quantities of samples with almost no preparation; the possibility to discriminate and determine the concentrations of intracellular metal and metal loosely bound to the grain surface in a single run; and finally, the determination of metal content in individual cells, reflecting the heterogeneity of a cell population, information that would be otherwise lost.