The tonoplast, a specific marker of embryogenic microspores of Datura cultured in vitro.

Microspores of Datura metel L. have a thin tonoplast which, upon culture in vitro, develops a more or less uniform coating or deposit (as early as 12 h). This response was specific for embryogenic microspores, thereby making it possible to distinguish them from the nonembryogenic microspores. Cytochemical tests indicated the presence of tannins in this deposit which persists only until the early globular stage of embryogenesis. Thus tannin-coated tonoplasts can be used as a reliable and specific cytological marker for microspores following the embryogenic pathway in vitro.