Abstract
Simple plasmodesmata between mesophyll and bundle sheath cells in actively expanding leaves of Salsola kali L. and roots of Epilobium hirsutum L. are shown to possess specialized structures, called sphincters, around their neck regions. The sphineters are made visible by the combined effects of tannic acid and heavy metal staining; they are localized just outside that area of the plasmalemma, which forms the collar around the entrance to each plasmodesmos. This localization corresponds to a very active area of the plasmodesmos/olasmalemma complex (i.e. enzyme activity and/or presence of strongly reducing substances).
Evidence is presented that these ring structures are structural equivalents to hypothetical sphincters performing some valve function; i.e. participating in the control of rates and directions of symplastic transport of solutes through plasmodesmata. The middle layer of the plasmalemma in the neck region is composed of closely-packed, globular subunits appearing in negative contrast. Apparently, these subunits correspond to particle clusters observed at the plasmodesmatal entrance in freeze-fracture preparations. They appear similar to particle clusters in animal tight junctions, and their possible function in providing electrical coupling via low resistance junctions between plant cells is discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Branton, D., Deamer, D.W.: Membrane structure, Protoplasmatologia II/E/1. Wien: Springer 1972
Brown, W.W., Mollenhauer, H., Johnson, C.: An electron microscope study of silver nitrate reduction in leaf cells. Am. J. Bot. 49, 57–63 (1962)
Evert, R.F., Eschrich, W., Heyser, W.: Distribution and structure of the plasmodesmata in mesophyll and bundle-sheath cells of Zea mays L. Planta 136, 77–89 (1977)
Futaesaku, Y., Mizuhira, V., Nakamura, H.: The new fixation method using tannic acid for electron microscopy and some observations of biological specimens. pp. 155–156. In: Proc. IVth Internatl. Congr. Histochem. Cytochem. 1972
Gunning, B.E.S.: Introduction to plasmodesmata. In: Intercellular communication in plants: Studies on plasmodesmata, pp. 1–13, Gunning, B.E.S., Robards, A.W., eds. Berlin, Heidelberg, New York: Springer 1976
Gunning, B.E.S., Robards, A.W.: Plasmodesmata: Current knowledge and outstanding problems. In: Intercellular communication in plants: Studies on plasmodesmata, pp. 297–311, Gunning, B.E.S., Robards, A.W., eds. Berlin, Heidelberg, New York: Springer 1976
Markham, R., Frey, S., Hills, G.J.: Methods for the enhancement of image detail and accentuation of structure in electron microscopy. Virology 20, 88–102 (1963)
McNutt, N.S., Weinstein, R.S.: Membrane ultrastructure at mammalian intercellular junctions. Progr. Biophys. Mol. Biol. 26, 45–101 (1973)
Mogensen, H.L.: Some histochemical, ultrastructural, and nutritional aspects of the ovule of Quercus gambelii. Am. J. Bot. 60, 48–54 (1973)
Northcote, D.H., Lewis, D.R.: Freeze-etched surfaces of membranes and organelles in the cells of pea root tips. J. Cell Sci. 3, 199–206 (1968)
Olesen, P.: Plasmodesmata between mesophyll and bundle sheath cells in relation to the exchange of C4-acids. Planta 123, 199–202 (1975)
Olesen, P.: Structure of chloroplast membranes as revealed by natural and experimental fixation with tannic acid: Particles in and on the thylakoid membrane. Biochem. Physiol. Pflanzen 172, 319–342 (1978)
Ophus, E.M., Gullvåg, B.M.: Localization of lead within leaf cells of Rhytidiadelphus squarrosus (Hedw.) Warnst. by means of transmission electron microscopy and X-ray microanalysis. Cytobios 10, 45–58 (1974)
Osmond, C.B., Smith, F.A.: Symplastic transport of metabolites during C4-photosynthesis. In: Intercellular communication in plants: Studies on Plasmodesmata, pp. 229–240, Gunning, B.E.S., Robards, A.W., eds. Berlin, Heidelberg, New York. Springer 1976
Robards, A.W.: A new interpretation of plasmodesmatal ultrastructure. Planta 82, 200–210 (1968)
Robards, A.W.: Particles associated with developing plant cell walls. Planta 88, 376–379 (1969)
Robards, A.W.: Plasmodesmata in higher plants. In: Intercellular communication in plants: Studies on plasmodesmata, pp. 15–57, Gunning, B.E.S., Robards, A.W., eds. Berlin, Heidelberg, New York: Springer 1976
Spanswick, R.M.: Symplasmic transport in tissue. In: Transport in plants II, pp. 35–53, Lüttge, U., Pitman, M.G., eds. Berlin, Heidelberg, New York: Springer 1976
Spanswick, R.M., Costerton, J.W.F.: Plasmodesmata in Nitella translucens: Structure and electrical resistance. J. Cell Sci. 2, 451–464 (1967)
Tilney, L.G., Bryan, J., Bush, D.J., Fujiwara, K., Mooseker, M.S., Murphy, D.B., Snyder, D.H.: Microtubules: evidence for 13 protofilaments. J. Cell. Biol. 59, 267–275 (1973)
Van Stevenick, R.F.M.: Cytochemical evidence for ion transport through plasmodesmata. In: Intercellular communication in plants: Studies on plasmodesmata, pp. 131–147, Gunning, B.E.S., Robards, A.W., eds. Berlin, Heidelberg, New York: Springer 1976
Vian, B., Rougier, M.: Ultrastructure des plasmodesmes après cryo-ultramicrotomie. J. Microscopie 20, 307–312 (1974)
Willison, J.H.M.: Plasmodesmata: a freeze-fracture view. Can. J. Bot. 54, 2842–2847 (1976)
Zee, S.-Y.: Fine structure of the differentiating sieve elements of Vicia faba. Aust. J. Bot. 17, 441–456 (1969)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Olesen, P. The neck constriction in plasmodesmata. Planta 144, 349–358 (1979). https://doi.org/10.1007/BF00391578
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00391578