Micro-PIXE in plant sciences: Present status and perspectives

Fundamental processes of plant physiology are affected or regulated by mineral nutrients. I fence understanding the mechanisms of nutrient uptake and their functions in plant metabolism is Of fundamental importance in both basic and applied plant studies. The present knowledge of ion uptake mechanisms is based mostly on techniques for bulk analysis, including analysis of small (mg-sized) samples but without spatially resolved results. On the other hand, advanced studies of elemental transport at a cellular level are conducted using techniques with high and very high spatial resolution, but with low sensitivity for elemental analysis. Thus the results obtained are usually restricted to macronutrients or elements present in high quantities. There is a high demand for studies of the functions of trace elements. In addition, it is known that, depending on their concentrations, elements can play different roles in plant life. Studies related to elemental deficiency and toxicity, as well as environmental pollution, require accurate. fully quantitative methods with good spatial resolution. Ideally, these studies should be conducted on organs and tissues as far down as the cellular level. This is where micro-PIXE has been applied until present and can in the near future play a much more important role. Progress is subject to closer collaboration between plant biologists and the PIXE community in terms of addressing problems of specimen preparation. refinement of analytical protocols such as quantitative elemental mapping and the interpretation of results. (C) 2002 Published by Elsevier Science B.V.