title: Changes in symplastic permeability during adventitious shoot regeneration in tobacco thin cell layers.
abstract: Thin cell layer (TCL) explants of tobacco (Nicotiana tabacum L.) were cultured in either a regeneration medium that resulted in formation of adventitious vegetative shoots or a non-regeneration (control) medium that maintained the TCLs but did not promote shoot formation. Microinjections were conducted on epidermal cells at 1- or 2-day intervals during the culture period (14 days) and also on meristematic regions as they appeared in regenerating TCLs. A fluorescein isothiocyanate-labelled peptide (F(Glu)3 MW 799) was used to assess the permeability of the symplast during adventitious shoot regeneration. A period of increased symplastic movement of F(Glu)3 was detected during day 2 of culture and was significantly greater in regenerating TCLs than in non-regenerating TCLs. This corresponded to the period of the first cell divisions and represents the re-initiation of a meristematic type of symplastic linkage between epidermal cells. A smaller increase in cell-to-cell movement within non-regenerating TCLs indicated a possible stress response as a factor in these changes. Movement of F(Glu)3 throughout the epidermal symplast of regenerating TCLs returned to pre-culture levels by the time of shoot primordia formation. F(Glu)3 movement was further down-regulated in non-regenerating TCLs, with a high degree of cell isolation observed. Within newly formed shoots, symplastic movement of F(Glu)3 cycled between high and low levels.
authors.affiliation: Department of Crop Sciences, The University of Sydney, NSW, Australia. cantrillL@agric.usyd.edu.au
authors.forename: L C
authors.initials: LC
authors.lastname: Cantrill
authors.forename: R L
authors.initials: RL
authors.lastname: Overall
authors.forename: P B
authors.initials: PB
authors.lastname: Goodwin
mesh_terms: D001692:Biological Transport; D002450:Cell Communication / Q000502:physiology; D002463:Cell Membrane Permeability / Q000502:physiology*; D046508:Culture Techniques; D003593:Cytoplasm / Q000502:physiology*; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D019441:Plant Epidermis / Q000254:growth & development / Q000502:physiology*; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology*; D014026:Nicotiana / Q000254:growth & development / Q000502:physiology*
chemical_list: D016650:Fluorescein-5-isothiocyanate