Dictyosomes

Dictyosome is the term used for the Golgi apparatus in plant cells and in many algae. It comprises one or more stacks of flattened, membrane-bound compartments called cisternae. Individual stacks, or dictyosomes, are distributed throughout the cytoplasm and can be mobile along the cytoskeleton, often associating with sites where proteins and lipids exit the endoplasmic reticulum.

Structure and organization: Each dictyosome contains a cis face, a medial region, and a trans face. The cis face receives transport vesicles from the endoplasmic reticulum, where proteins and lipids are delivered. Through sequential modification in the medial cisternae, final products accumulate in the trans cisternae, which then dispatch vesicles to the plasma membrane, vacuoles, or the cell wall. In plants, a specialized trans-Golgi network (TGN) functions as a sorting hub for cargo destined to various destinations.

Function: Dictyosomes modify, glycosylate, and sort secretory and membrane components synthesized in the ER. They participate in the synthesis of cell-wall polysaccharides such as pectin and hemicellulose and generate vesicles that contribute to cell wall assembly and secretion. They also deliver enzymes and membrane lipids to destinations including the plasma membrane and vacuoles.

Dynamics and context: The plant Golgi apparatus is highly dynamic, with dictyosomes continually budding and receiving vesicles. During cytokinesis in plant cells, dictyosomes supply vesicles that fuse to form the cell plate, separating the daughter cells. In modern descriptions, the apparatus is often explained by the cisternal maturation model, in which cisternae move and change identity as cargo progresses.

Taxonomy: The term dictyosome is primarily used in plant biology and some algal contexts; in many animal-cell studies the term Golgi apparatus is used for the single, perinuclear organelle. Regardless of terminology, the structural and functional features are conserved.