ULTRASTRUCTURAL ASPECTS OF PROGRAMMED CELL DEATH IN THE EXOCARP OIL GLANDS OF MANDARIN (CITRUS DELICIOSA TEN.)

Abstract

In the exocarp of mandarin fruit (Citrus deliciosa Ten.), numerous globular/ovoid oil glands occur. In the centre of each gland, an essential oil-accumulating cavity is formed by a process of cell lysis. This process is induced by PCD which becomes ultrastructurally evident by the presence of a large number of fragmented ER-elements with a dark content. They appear only at the stage of PCD initiation and they disappear afterwards. ER-elements are scattered over the entire cytoplasmic area and do not locally aggregate or associate with other cell organelles and particularly the vacuoles. TEM observations favour the interpretation that ER involves in PCD of oil gland cells by releasing hydrolytic enzymes directly to the cytosol.

Keywords

• seed
• ruminate embryo
• Citrus deliciosa Ten.
• endoplasmic reticulum (ER)
• hydrolytic enzymes
• oil cavities