Histological distribution of orange G-specific cytoplasmic globules and safranin-aniline blue-specific cytoplasts in the shoot of Kalanchoe blossfeldiana

Large spherical cellular inclusions in Kalanchoe blossfeldiana were selectively stained using aqueous safranin followed by citrate buffered aniline blue-orange G pH 3.5. The globules were stained bright orange. Other cellular inclusions that filled entire cells were brightly stained shades of pink, red, or purple. Tissue fixed in 5% glutaraldehyde and 2% calcium acetate revealed the globules and inclusions throughout the shoot. Globules were present in the pith parenchyma cells and in the layer of cortex just outside the vascular tissue from just below the apical meristem to the crown. Globules were also found in parenchyma cells in petioles and in mesophyll cells surrounding vascular tissue in leaves. Cellular inclusions in the form of whole dense protoplasts were more frequently found in a continuous layer just under the epidermis in the stem, and in the leaves were concentrated immediately under the epidermis. Both the globules and whole cell inclusions were also randomly scattered through stem and leaf tissue. Various histochemical tests did not identify the composition of either the globules or the whole cell inclusions, but eliminated polysaccharides, protein, and unsaturated lipids as the major structural components of the globules. Some whole-cell inclusions in fresh sections gave positive reactions for tannin, protein, and polysaccharides.