title: Plasmodesmal-mediated cell-to-cell transport in wheat roots is modulated by anaerobic stress.
abstract: Cell-to-cell transport of small molecules and ions occurs in plants through plasmodesmata. Plant roots are frequently subjected to localized anaerobic stress, with a resultant decrease in ATP. In order to determine the effect of this stress on plasmodesmal transport, fluorescent dyes of increasing molecular weight (0.46 to 1OkDa) were injected into epidermal and cortical cells of 3-day-old wheat roots, and their movement into neighboring cells was determined by fluorescence microscopy. Anaerobiosis was generated by N2 gas or simulated by the presence of sodium azide, both of which reduced the ATP levels in the tissue by over 80%. In the absence of such stress, the upper limit for movement, or size exclusion limit (SEL), of cortical plasmodesmata was <1 kDa. The ATP analogue TNP-ADP (mw 681) moved across the plasmodesmata of unstressed roots, indicating that plasmodesmata may be conduits for nucleotide (ATP and ADP) exchange between cells. Upon imposition of stress, the SEL rose to between 5 and 10 kDa. This response of plasmodesmata to a decrease in the level of ATP suggests that they are constricted by an ATP-dependent process so as to maintain a restricted SEL. When roots are subjected to anaerobic stress, an increase in SEL may permit enhanced delivery of sugars to the affected cells of the root where anaerobic respiration could regenerate the needed ATP.
authors.affiliation: Department of Botany, University of Washington, Seattle, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Cleland
authors.forename: T
authors.initials: T
authors.lastname: Fujiwara
authors.forename: W J
authors.initials: WJ
authors.lastname: Lucas
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000693:Anaerobiosis; D001386:Azides / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D005456:Fluorescent Dyes; D009584:Nitrogen; D010316:Particle Size; D018517:Plant Roots / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D014908:Triticum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001386:Azides; D005456:Fluorescent Dyes; D000255:Adenosine Triphosphate; D009584:Nitrogen