Cytochemical Studies on Phytochrome-Mediated Changes of Ca2+ Localization in Etiolated Oat Coleoptile Cells

The antimonate-staining procedure and X-ray microanalysis techniquewere used to determine the pattern of Ca₂₊ localization in etiolatedoat (Avena sativa L.) coleoptile parenchyma cells. Precipitatesof calcium antimonate, indicating the presence of Ca₂₊ and confirmedby X-ray microanalysis, were found associated with the outerand inner surfaces of the plasma membrane of cells of dark-grownseedlings. After exposure of seedlings to red light, precipitatesof calcium antimonate were additionally observed in cisternaeof the endoplasmic reticulum. In the cells of oat coleoptilesexposed to red light and then followed immediately by farredlight, Ca₂₊ was observed on the outside of the plasma membrane,in cell walls and in the vacuoles. The results suggest thatphytochrome mediates the regulation of the intracellular Ca₂₊localization. Key words: Antimonate procedure, Avena sativa L., Ca²⁺ (localization), phytochrome, X-ray microanalysis