Subceliular Localization of Inorganic Ions in Plant Cells by in vivo Precipitation.

Uptake of iodide (as a possible tracer of chloride) by barley roots preloaded with thallium (as a tracer of potassium) resulted in in vivo precipitation of the almost insoluble yellow thallium iodide. Electron microscopic observation revealed in several cells a dense precipitate of thallium iodide within the cisternae of the endoplasmic reticulum, which suggests that this membrane system is involved in intracellular ion transport.