title: Auxin and chloroplast movements.
abstract: Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin-mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p-chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF(TIR1)-Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF(TIR1)-Aux/IAA-ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins.
authors.affiliation: Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Eckstein
authors.affiliation: Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Weronika
authors.initials: W
authors.lastname: Krzeszowiec
authors.affiliation: The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Waligórski
authors.affiliation: Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Halina
authors.initials: H
authors.lastname: Gabryś
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D001692:Biological Transport / Q000187:drug effects; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008027:Light; D058503:Mesophyll Cells / Q000187:drug effects / Q000378:metabolism; D009068:Movement; D009154:Mutation / Q000235:genetics; D056949:Phototropins / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D056949:Phototropins; D010937:Plant Growth Regulators; D012333:RNA, Messenger