title: The role of microtubules in guard cell function.
abstract: Guard cells are able to sense a multitude of environmental signals and appropriately adjust the stomatal pore to regulate gas exchange in and out of the leaf. The role of the microtubule cytoskeleton during these stomatal movements has been debated. To help resolve this debate, in vivo stomatal aperture assays with different microtubule inhibitors were performed. We observed that guard cells expressing the microtubule-binding green fluorescent fusion protein (green fluorescent protein::microtubule binding domain) fail to open for all major environmental triggers of stomatal opening. Furthermore, guard cells treated with the anti-microtubule drugs, propyzamide, oryzalin, and trifluralin also failed to open under the same environmental conditions. The inhibitory conditions caused by green fluorescent protein::microtubule binding domain and these anti-microtubule drugs could be reversed using the proton pump activator, fusicoccin. Therefore, we conclude that microtubules are involved in an upstream event prior to the ionic fluxes leading to stomatal opening. In a mechanistic manner, evidence is presented to implicate a microtubule-associated protein in this putative microtubule-based signal transduction event.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Marcus
authors.forename: R C
authors.initials: RC
authors.lastname: Moore
authors.forename: R J
authors.initials: RJ
authors.lastname: Cyr
mesh_terms: D001549:Benzamides / Q000494:pharmacology; D019470:Biolistics; D003078:Colchicine / Q000494:pharmacology; D003624:Darkness; D004136:Dinitrobenzenes / Q000494:pharmacology; D017930:Genes, Reporter; D005813:Genes, Synthetic; D049452:Green Fluorescent Proteins; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D008870:Microtubules / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D018515:Plant Leaves / Q000166:cytology / Q000502:physiology; D030821:Plants, Genetically Modified / Q000166:cytology / Q000254:growth & development; D013424:Sulfanilamides; D014274:Trifluralin / Q000494:pharmacology; D031307:Vicia faba / Q000166:cytology* / Q000254:growth & development / Q000502:physiology
chemical_list: D001549:Benzamides; D004136:Dinitrobenzenes; D008164:Luminescent Proteins; D013424:Sulfanilamides; D049452:Green Fluorescent Proteins; C001059:pronamide; C012465:oryzalin; D014274:Trifluralin; D003078:Colchicine