title: Defining the selectivity of processes along the auxin response chain: a study using auxin analogues.
abstract: The mode of action of auxin is based on its non-uniform distribution within tissues and organs. Despite the wide use of several auxin analogues in research and agriculture, little is known about the specificity of different auxin-related transport and signalling processes towards these compounds. Using seedlings of Arabidopsis thaliana and suspension-cultured cells of Nicotiana tabacum (BY-2), the physiological activity of several auxin analogues was investigated, together with their capacity to induce auxin-dependent gene expression, to inhibit endocytosis and to be transported across the plasma membrane. This study shows that the specificity criteria for different auxin-related processes vary widely. Notably, the special behaviour of some synthetic auxin analogues suggests that they might be useful tools in investigations of the molecular mechanism of auxin action. Thus, due to their differential stimulatory effects on DR5 expression, indole-3-propionic (IPA) and 2,4,5-trichlorophenoxy acetic (2,4,5-T) acids can serve in studies of TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALLING F-BOX (TIR1/AFB)-mediated auxin signalling, and 5-fluoroindole-3-acetic acid (5-F-IAA) can help to discriminate between transcriptional and non-transcriptional pathways of auxin signalling. The results demonstrate that the major determinants for the auxin-like physiological potential of a particular compound are very complex and involve its chemical and metabolic stability, its ability to distribute in tissues in a polar manner and its activity towards auxin signalling machinery.
authors.affiliation: Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, Rozvojová 263, 16502, Prague 6, Czech Republic; Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Ghent, Belgium; Developmental and Cell Physiology of Plants, Institute of Science and Technology (IST Austria), 3400, Klosterneuburg, Austria.
authors.forename: Sibu
authors.initials: S
authors.lastname: Simon
authors.forename: Martin
authors.initials: M
authors.lastname: Kubeš
authors.forename: Pawel
authors.initials: P
authors.lastname: Baster
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Robert
authors.forename: Petre Ivanov
authors.initials: PI
authors.lastname: Dobrev
authors.forename: Jiří
authors.initials: J
authors.lastname: Friml
authors.forename: Jan
authors.initials: J
authors.lastname: Petrášek
authors.forename: Eva
authors.initials: E
authors.lastname: Zažímalová
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009154:Mutation / Q000235:genetics; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D013535:Suspensions; D014026:Nicotiana / Q000166:cytology
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D013535:Suspensions
keywords: 2,4-dichlorophenoxyacetic acid (2,4-D); auxin analogues; auxin signalling; auxin transport; indole-3-acetic acid (IAA); indole-3-butyric acid (IBA); naphthalene-1-acetic acid (NAA)