Simple, but not branched, plasmodesmata allow the nonspecific trafficking of proteins in developing tobacco leaves

Cell. 1999 Jun 11;97(6):743-54. doi: 10.1016/s0092-8674(00)80786-2.


Leaves undergo a sink-source transition during which a physiological change occurs from carbon import to export. In sink leaves, biolistic bombardment of plasmids encoding GFP-fusion proteins demonstrated that proteins with an Mr up to 50 kDa could move freely through plasmodesmata. During the sink-source transition, the capacity to traffic proteins decreased substantially and was accompanied by a developmental switch from simple to branched forms of plasmodesmata. Inoculation of sink leaves with a movement protein-defective virus showed that virally expressed GFP, but not viral RNA, was capable of trafficking between sink cells during infection. Contrary to dogma that plasmodesmata have a size exclusion limit below 1 kDa, the data demonstrate that nonspecific "macromolecular trafficking" is a general feature of simple plasmodesmata in sink leaves.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Carbon / metabolism
  • Genetic Vectors / genetics
  • Green Fluorescent Proteins
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Plant Leaves / metabolism
  • Plant Proteins / metabolism*
  • Plant Viral Movement Proteins
  • Plants, Toxic*
  • Potexvirus / genetics
  • RNA, Messenger / metabolism
  • RNA, Viral / metabolism
  • Tobacco / metabolism*
  • Viral Proteins / metabolism


  • Luminescent Proteins
  • Plant Proteins
  • Plant Viral Movement Proteins
  • RNA, Messenger
  • RNA, Viral
  • Viral Proteins
  • Green Fluorescent Proteins
  • Carbon