Ultrastructure of cell wall and plugs of tobacco pollen tubes after chemical extraction of polysaccharides.

Tobacco pollen tubes grown in vitro and from pollinated tobacco styles were treated by chemical solvents to remove one or more of the following polysaccharides from the tube walls: pectin (ethylenediamine tetraacetic acid); hemicellulose (alkali); callose (alkali; potassium hypochlorite); cellulose (cuprammonium); and all polysaccharides with exception of cellulose (H2O2/glacial acetic acid). Both the inner tube wall, which we had regarded as the secondary wall, and the plugs contained, in addition to callose, microfibrils of cellulose and "non-cellulosic" microfibrils that had "pectin-like" properties. When using the expressions callosic or callose layer and callose plugs in reference to pollen tubes, one should realize that they do not imply the exclusive presence of callose in the inner tube wall layer and its localized thickenings.