Summary
There is a predictable and well defined variation in numbers of plasmodesmata in roots ofAzolla. As the apical cell of the root ages, it lays down walls with progressively fewer plasmodesmata, thereby gradually cutting itself off from the rest of the root (Gunning 1978). Electrical coupling was examined between the apical cell and an adjacent merophyte in roots of various lengths. The apical cell becomes increasingly electrically isolated from the rest of the root as it ages. Electrical coupling is strongly correlated with the number of the plasmodesmata between the coupled cells. The resistance of a plasmodesma, as estimated from equivalent electrical circuits, was 150–600 times more resistive than a value based on theoretical considerations. No evidence was found for a change in the physiology of plasmodesmata as the root ages. Coupling experiments, both on root hairs and at the apex, gave some suggestion that plasmodesmata may be less resistive towards the apical cell than away from it.
Similar content being viewed by others
References
Anderson, W. P., Hendrix, D. L., Higinbotham, N., 1974: Higher plant cell membrane resistance by a single intracellular electrode method. Plant Physiol.53, 122–124.
Bostrom, T. E., Walker, N. A., 1975: Intercellular transport in plants I. The flux of chloride and the electric resistance inChara. J. exp. Bot.26, 767–782.
Drake, G. A., Carr, D. J., Anderson, W. P., 1978: Plasmolysis, plasmodesmata, and the electrical coupling of oat coleoptile cells. J. exp. Bot.29, 1205–1214.
Etherton, B., Keifer, D. W., Spanswick, R. M., 1977: Comparison of three methods for measuring electrical resistances of plant cell membranes. Plant Physiol.60, 684–688.
Evans, E. C. III.,Vaughan, B. E., 1966: New methods for effecting watertight seals on corn roots. Plant Physiol.41, 1077–1078.
Goldsmith, H. M., Cleland, R. E., 1978: The contribution of tonoplast and plasma membrane to the electrical properties of a higher-plant cell. Planta143, 261–265.
Goldsmith, M. H., Fernandez, H. R., Goldsmith, T. H., 1972: Electrical properties of parenchymal cell membranes in the oat coleoptile. Planta102, 302–323.
Goldsmith, T. H., Goldsmith, M. H. M., 1978: The interpretation of intracellular measurements of membrane potential, resistance and coupling in cells of higher plants. Planta143, 267–274.
Greenham, C. G., 1966: The electrical resistances of the plasma membrane and tonoplast in higher plants. Planta69, 150–157.
Gunning, B. E. S., 1978: Age-related and origin-related control of the numbers of plasmodesmata in cell walls of developingAzolla roots. Planta143, 181–190.
Gunning, B. E. S., Hughes, J. E., Hardham, A. R., 1978: Formative and proliferative divisions, cell differentiation and developmental changes in the meristem ofAzolla roots. Planta143, 121–144.
—,Robards, A. W., 1976: Plasmodesmata: Current knowledge and outstanding problems. In: Intercellular communication in plant: studies on plasmodesmata (Gunning, B. E. S., Robards, A. W., eds.), pp. 331–338. Berlin-Heidelberg-New York: Springer.
Higinbotham, N., Hope, A. B., Findlay, G. P., 1964: Electrical resistance of cell membranes ofAvena coleoptiles. Science143, 1448–1449.
Loewenstein, W. R., Kanno, Y., 1964: Studies on an epithelial (gland) cell junction. I. Modifications of surface membrane permeability. J. Cell Biol.22, 565–586.
Overall, R. L.,Gunning, B. E. S., 1982: Intercellular communication in the filamentous green algaOedogonium: electrical coupling and ultrastructure of plasmodesmata. In preparation.
—,Wolfe, J., Gunning, B. E. S., 1982: Intercellular communication inAzolla roots: I. Ultrastructure of plasmodesmata. Protoplasma111, 134–150.
Peters, G. A., Mayne, B. C., 1974: TheAzolla, Anabaena azollae relationship. I. Initial characterisation of the association. Plant. Physiol.53, 813–819.
Racusen, R. H., 1976: Phytochrome control of electrical potentials and intercellular coupling in oat-coleoptile tissue. Planta132, 25–29.
Rona, J. P., Cornel, D., 1979: Résistances électriques chez les cellules les protoplastes et les vacuoles isoléesd'Acer pseudoplatanus L. Physiol. Veg.17 (1), 1–11.
Socolar, S. J., 1977: The coupling coefficient as an index of junctional conductance. J. Memb. Biol.34, 29–37.
Spanswick, R. M., 1972: Electrical coupling between cells of higher plants: A direct demonstration of intercellular communication. Planta102, 215–227.
Spanswick, R., Costerton, J., 1967: Plasmodesmata inNitella translucens: Structure and electrical resistance. J. Cell Sci.2, 451–464.
Spitzer, N. C., 1970: Low resistance connexions between cells in the developing anther of the lily. J. Cell Biol.45, 565–575.
Tangl, E., 1879: Über offene Communicationen zwischen den Zellen des Endosperms einiger Samen. Jb. wiss. Bot.12, 170–190.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Overall, R.L., Gunning, B.E.S. Intercellular communication inAzolla roots: II. Electrical coupling. Protoplasma 111, 151–160 (1982). https://doi.org/10.1007/BF01282072
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01282072