Characterization of the structural inclusions in the latex of banana (Musa sp.)

Abstract

Because of the importance of latex in indicating the water relations of the banana plant, the structural inclusions in the latex have been examined using microscopic, cytochemical, and analytical methods. Banana latex is a colloidal suspension of diverse organelles. The major organelles have been identified as lipid globules, lutoids, and cytoplasmic fragments. A few raphides and threadlike inclusions were also found. The lipid globules were comparatively large and most of them had an electron-opaque crust around them. The lutoids occurred in two morphologically different forms: globular vesicles and crystalloid vesicles. They were osmotically active and a maximum number of them were in the expanded state when the solute potential of the suspending medium was approximately −0.5 MPa. They had a unit membrane around them and various membraneous structures inside. The crystalloid lutoids had long hexagonal crystals inside them. Some of the globular lutoids had nuclear materials in them. The cytoplasmic fragments occurred as globular structures with a plasma membrane around them. They had granular contents and showed the derivation of vesicles from the plasma membrane. From their staining and ultrastructural characteristics, it is believed that the lutoids have vacuolysosomal activity.