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Phloem pp 215-221 | Cite as

Quantification of Symplasmic Phloem Loading Capacity with Live-Cell Microscopy

  • Helle Juel Martens
  • Chen Gao
  • Johannes LiescheEmail author
Protocol
Part of the Methods in Molecular Biology book series (MIMB, volume 2014)

Abstract

Sugars produced by photosynthesis in leaves get transported to other organs in the phloem vascular tissue. Three general mechanisms have been proposed for the loading of sugars into the phloem. These differ in the involvement of active transport across the phloem cell’s membrane and their capacity for passive intercellular transport through plasmodesmata. This capacity for diffusion from the mesophyll into the phloem cells can be quantified by live-cell microscopy. Instead of sugar molecules, the movement of fluorescent tracers of similar size can be observed. In this chapter, a simple method is described that allows quantification of plasmodesmata-mediated intercellular diffusion across the mesophyll-bundle sheath interface and the bundle sheath-phloem cell interfaces. The fluorescent tracer carboxyfluorescein is loaded into intact leaves and its diffusion monitored with confocal microscopy after photobleaching of a bundle sheath cell.

Key words

Plasmodesmata Phloem loading Carbon allocation Live-cell microscopy Fluorescent tracer Photobleaching 

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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Helle Juel Martens
    • 1
  • Chen Gao
    • 2
  • Johannes Liesche
    • 2
    Email author
  1. 1.Department of Geosciences and Natural ResourcesUniversity of CopenhagenCopenhagenDenmark
  2. 2.College of Life SciencesNorthwest A&F UniversityYanglingChina

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