Planta

, Volume 192, Issue 2, pp 165–175

Microelectrode-recorded development of the symplasmic autonomy of the sieve element/companion cell complex in the stem phloem ofLupinus luteus L.

  • Aart J. E. van Bel
  • Harold V. M. van Rijen
Article

DOI: 10.1007/BF01089031

Cite this article as:
van Bel, A.J.E. & van Rijen, H.V.M. Planta (1994) 192: 165. doi:10.1007/BF01089031

Abstract

From the cambial stage onwards, the symplasmic autonomy of sieve element/companion cell complexes (SE/CC-complexes) was followed in stems ofLupinus luteus L. by microinjection techniques. The membrane potential and the symplasmic autonomy of the mature SE/CC-complex was measured in successive internodes. A microelectrode was inserted into SE/CC-complexes or phloem parenchyma cells (PPs) and, after stabilization of the membrane potential, the membrane-impermeant fluorescent dye Lucifer Yellow CH (LYCH) was injected intracellullary. The plasmodesmata of the cambial SE/ CC precursor were gradually shut off at all interfaces beginning at the walls to be transformed into sieve plates. In the course of maturation, symplasmic discontinuity was maintained at the longitudinal walls of the complex. In the transverse walls of the SE, wide sieve pores were formed giving rise to longitudinal multicellular symplasmic domains of SE/CC-complexes. Symplasmic isolation of the files of mature SE/CC-complexes was demonstrated in several ways: (i) the membrane potential of the SE/CC-complexes (between -100 mV and -130 mV) was consistently more negative than that of the PPs (between-50 and -100 mV), (ii) No exchange of LYCH was observed between SE/CC-complexes and the PPs. Lucifer Yellow CH injected into the SEs exclusively moved to the associated CCs and to other SE/CC-complexes whereas LYCH injected into the PPs was only displaced to other PPs. (iii) The electrical coupling ratio between adjacent PPs was ten times higher than that between SE/CC-complex and PP. A gradient in the membrane potential of the SE/CC-complexes along the stem was not conclusively demonstrated.

Key words

Cellular ontogenyLupinusMembrane potentialPhloem translocationSieve element/companion cell complexSymplasmic (dis)continuity

Abbreviations

LYCH

Lucifer Yellow CH

Δψ

membrane potential

PMF

proton-motive force

PP

phloem parenchyma cell

SE/CC-complex

sieve element/companion cell complex

SR-G

sulphorhodamine G

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Aart J. E. van Bel
    • 1
  • Harold V. M. van Rijen
    • 1
  1. 1.Transport Physiology Research Group, Department of Plant Ecology and Evolutionary BiologyUniversity of UtrechtUtrechtThe Netherlands
  2. 2.Department of PhysiologyUniversity of AmsterdamAmsterdamThe Netherlands