Regulation of solute flux through plasmodesmata in the root meristem

Plant Physiol. 2011 Apr;155(4):1817-26. doi: 10.1104/pp.110.168187. Epub 2011 Feb 16.

Abstract

Plasmodesmata permit solutes to move between cells nonspecifically and without having to cross a membrane. This symplastic connectivity, while straightforward to observe using fluorescent tracers, has proven difficult to quantify. We use fluorescence recovery after photobleaching, combined with a mathematical model of symplastic diffusion, to assay plasmodesmata-mediated permeability in the Arabidopsis (Arabidopsis thaliana) root meristem in wild-type and transgenic lines, and under selected chemical treatments. The permeability measured for the wild type is nearly 10-times greater than previously reported. Plamodesmal permeability remains constant in seedlings treated with auxin (30 mM indoleacetic acid for 2 and 24 h; 100 nm indoleacetic acid for 2 h); however, permeability is diminished in two lines previously reported to have impaired plasmodesmal function as well as in wild-type seedlings treated for 24 h with 0.6 mM tryptophan. Moreover, plasmodesmal permeability is strongly altered by applied hydrogen peroxide within 2 h of treatment, being approximately doubled at a low concentration (0.6 mM) and nearly eliminated at a higher one (6 mM). These results reveal that the plasmodesmata in the root meristem carry a substantial flux of small molecules and that this flux is subject to rapid regulation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / metabolism
  • Fluoresceins / metabolism
  • Fluorescence Recovery After Photobleaching
  • Hydrogen Peroxide / pharmacology
  • Indoleacetic Acids / metabolism*
  • Meristem / metabolism*
  • Models, Theoretical
  • Permeability
  • Plant Roots / metabolism*
  • Plants, Genetically Modified / metabolism
  • Plasmodesmata / metabolism*
  • Tryptophan / metabolism

Substances

  • Fluoresceins
  • Indoleacetic Acids
  • carboxyfluoresceindiacetate
  • Tryptophan
  • Hydrogen Peroxide