title: Influence of cytokinins on the expression of phosphate starvation responsive genes in Arabidopsis.
abstract: The increase in the ratio of root growth to shoot growth that occurs in response to phosphate (Pi) deprivation is paralleled by a decrease in cytokinin levels under the same conditions. However, the role of cytokinin in the rescue system for Pi starvation remains largely unknown. We have isolated a gene from Arabidopsis thaliana (AtIPS1) that is induced by Pi starvation, and studied the effect of cytokinin on its expression in response to Pi deprivation. AtIPS1 belongs to the TPSI1/Mt4 family, the members of which are specifically induced by Pi starvation, and the RNAs of which contain only short, non-conserved open reading frames. Pi deprivation induces AtIPS1 expression in all cells of wild-type plants, whereas in the pho1 mutant grown on Pi-rich soils, AtIPS1 expression in the root was delimited by the endodermis. This supports the view that pho1 is impaired in xylem loading of Pi, and that long-distance signals controlling the Pi starvation responses act via negative control. Exogenous cytokinins repress the expression of AtIPS1 and other Pi starvation-responsive genes in response to Pi deprivation. However, cytokinins did not repress the increase in root-hair number and length induced by Pi starvation, a response dependent on local Pi concentration rather than on whole-plant Pi status. Our results raise the possibility that cytokinins may be involved in the negative modulation of long-distance, systemically controlled Pi starvation responses, which are dependent on whole-plant Pi status.
authors: Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain.
authors: A C
authors: AC
authors: Martín
authors: J C
authors: JC
authors: del Pozo
authors: J
authors: J
authors: Iglesias
authors: V
authors: V
authors: Rubio
authors: R
authors: R
authors: Solano
authors: A
authors: A
authors: de La Peña
authors: A
authors: A
authors: Leyva
authors: J
authors: J
authors: Paz-Ares
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D001483:Base Sequence; D003583:Cytokinins / Q000494:pharmacology*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010710:Phosphates / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D003583:Cytokinins; D018076:DNA, Complementary; D010710:Phosphates; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C105499:phosphate starvation-induced protein 1, plant; D005966:Glucuronidase