Symplasmic connections between sieve element and companion cell in the stem phloem ofVicia faba L. have a molecular exclusion limit of at least 10 kDa |
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| Authors: | Ronald Kempers Aart J. E. van Bel |
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| Affiliation: | (1) Transport Physiology Research Group, Department of Plant Ecology and Evolutionary Biology, Utrecht University, Sorbonnelaan 16, NL-3584 CA Utrecht, The Netherlands;(2) Botanisches Institut 1, Justus-Liebig University, Senckenbergstrasse 17, D-35390 Giessen, Germany |
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| Abstract: | High-molecular-weight fluorochromes were intracellularly injected into a sieve element of the fascicular stem phloem ofVicia faba L., using a modified membrane-potential-recording pressure probe. After stabilization of the membrane potential following microelectrode impalement, either LYCH (Lucifer Yellow CH), 4.4-kDa FITC-dextran (fluoresceinisothiocyanate-dextran) conjugate, or 3-kDa, 10-kDa or 40-kDa LYCH-dextran conjugate was microinjected into the sieve element. Longitudinal fluorochrome movement across the sieve plates and lateral displacement to the companion cells was detected with all the probes except the 40-kDa conjugate. This indicates that the molecular exclusion limit of the pore/plasmodesma units between a sieve element and a companion cell in the fascicular stem phloem ofVicia faba lies between 10 kDa and 40 kDa.Abbreviations FITC fluoresceinisothiocyanate - LYCH Lucifer Yellow CH - MEL molecular exclusion limit - PPU pore/plasmodesma unit - SE/CC-complex sieve element/companion cell complex |
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| Keywords: | Fluorescent dextran Intracellular microinjection Molecular exclusion limit Pore/plasmodesma unit Sieve element/companion cell complex Vicia |
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