title: Regulation of solute flux through plasmodesmata in the root meristem.
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.
authors.affiliation: Physics Department, Simon's Rock College, Great Barrington, Massachusetts 01230, USA.
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Rutschow
authors.forename: Tobias I
authors.initials: TI
authors.lastname: Baskin
authors.forename: Eric M
authors.initials: EM
authors.lastname: Kramer
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism*; D018519:Meristem / Q000378:metabolism*; D008962:Models, Theoretical; D010539:Permeability; D018517:Plant Roots / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism; D031425:Plasmodesmata / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
chemical_list: D005452:Fluoresceins; D007210:Indoleacetic Acids; C027780:carboxyfluoresceindiacetate; D014364:Tryptophan; D006861:Hydrogen Peroxide