X-Ray Microanalytical Studies on Two Modes of Strontium Binding in Fronds of Lemna minor

Abstract

X-ray microprobe analysis of freeze-fractured Lemna fronds has shown that zinc (Zn) and cadmium (Cd) are not incorporated into oxalate crystals in idioblasts, whereas strontium (Sr) is readily incorporated as an alternative to calcium (Ca). Ca and Sr are uniformly distributed throughout the crystal bundle when both elements are present in the nutrient solution. However, in neighbouring, non-idioblast cells Sr (but not Ca) may also be incorporated into globular deposits of less than 1 ¼m diameter. These globules contain the mineral elements potassium and phosphorus and their composition appears to be identical to that of phytate globules which contain Zn or Cd under conditions of Zn or Cd toxicity.