Plant Exocytosis, Endocytosis and Membrane Recycling in Turgid Cells


In plant cells, growth is dependent on cell wall building and plasma membrane growth. Secretion of proteins is vital for cell function and cell–cell communication. The fusion of secretory vesicles at the plasma membrane (exocytosis) is a key mechanism because it delivers proteins and lipids to the plasma membrane and proteins and polysaccharides to the cell wall. The anterograde flow of membranes is balanced by endocytosis, which retrieves excess membrane and recycles plasma membrane receptors and transporters. Exocytosis and endocytosis have recently been shown to underpin the establishment of cell polarity which is key to the control of plant developmental processes. The balance of exocytosis and endocytosis is, therefore, crucial to both plant signalling and development, is highly regulated and is an exciting subject of current research.

Key Concepts:

  • Exocytosis is the fusion of secretory vesicles with the plasma membrane.

  • Endocytosis retrieves lipids and proteins from the plasma membrane.

  • The balance of exocytosis and endocytosis regulates cell growth, polarity and expansion, ultimately underpinning all plant developmental processes.

Keywords: plants; vesicle trafficking; secretory pathway; exocytosis; endocytosis; plasma membrane; cell wall; Golgi; endosomes; clathrin‐coated vesicles

Figure 1.

Schematic diagram of the plant secretory pathway. Secretory vesicles (circles) transport polysaccharide precursors, membrane and proteins to the (PM). Coordination of the rate and distribution of exocytosis (red arrows) and endocytosis (blue arrows) is crucial to allow the cell to balance the demands of growth and differentiation. The exocytic and endocytic routes intersect at the (TGN/EE). The concentration of plasma membrane proteins such as signalling receptors can be regulated by endocytosis and degradation of the proteins in the (MVB/PVC) and eventually in the vacuole. ER, endoplasmic reticulum; CW, cell wall.

Figure 2.

The tip of the pollen tube. Here very active exocytosis allows the tube to grow rapidly down the style of the flower and deliver the male gametes for fertilisation. Reproduced from Lancelle et al. by permission of the authors and Springer (Wien).

Figure 3.

Venus fly trap, Dionaea muscipula. This insectivorous plant obtains much of its nitrogen and other elements as protein from insects that are trapped on the sticky leaves. Secretion of hydrolytic enzymes by glands on the leaf surface is essential for the digestion of the prey. This secretion is achieved by exocytosis of vesicles containing the enzymes. Photograph courtesy of Dr Alastair Culham (Department of Botany, The University of Reading).

Figure 4.

Cell plate (arrowed) growing outwards to divide the two daughter nuclei. Tobacco BY2 cells were stained with aniline blue. Photograph courtesy of Dr Pim van Kesteren (Department of Horticulture, The University of Reading).

Figure 5.

Exocytotic configurations in the plasma membrane of a sycamore cell. This face view of the membrane reveals horseshoe shapes where the secretory vesicles, after fusion with the plasma membrane, have been flattened against the membrane. See Staehelin and Chapman and Battey et al. for further details.

Figure 6.

Transient or permanent fusion – alternatives according to need? (a) Fluctuations in plasma membrane capacitance signal recorded in a cell‐attached patch of a maize coleoptile protoplast. (b) Interpretation. Left: rapid fluctuations represent transient fusion, cargo is discharged but the vesicle matrix and membrane recycled. Right: step change in capacitance reflecting full fusion and membrane incorporation. Cyt, cytoplasm; Out, outside of plasma membrane. Reproduced from Thiel and Battey by permission of the authors and Kluwer Academic Publishers (Dordrecht, The Netherlands).



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Further Reading

Grefen C and Blatt MR (2008) SNAREs – molecular governors in signalling and development. Current Opinion in Cell Biology 11: 600–609.

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Van Damme D, Inze D and Russinova E (2008) Vesicle trafficking during somatic cytokinesis. Plant Physiology 147: 1544–1552.

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How to Cite close
Frigerio, Lorenzo(Jun 2010) Plant Exocytosis, Endocytosis and Membrane Recycling in Turgid Cells. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0001676.pub2]