ULTRASTRUCTURAL LOCALIZATION OF SOLANIDINE IN POTATO TUBERS 1

ABSTRACT Microscopic and ultrastructural cytochemical techniques were utilized in an attempt to localize the site of solanine synthesis in potato (Solarium tuberosum L. cv Russett Burbank) tubers. Application of an alkaloid extract of potato tissues to TLC plates before and after incubating with digitonin indicated solanidine, a direct precursor in the biosynthesis of solanine, was removed by digitonin. In the electron micrographs, the solanidine‐digitonin complex was recognized as darkly stained needles or spicules. These spicules were observed primarily in the vacuoles of sprouted tips with a few also noted in the cytoplasm and peridermal tissue. This study demonstrated only minute quantities of solanidine present. The small quantities observed may reflect a rapid conversion of solanidine to solanine or chaconine or insensitivity of the method.