title: Shoot to root communication is necessary to control the expression of iron-acquisition genes in Strategy I plants.
abstract: Previous research showed that auxin, ethylene, and nitric oxide (NO) can activate the expression of iron (Fe)-acquisition genes in the roots of Strategy I plants grown with low levels of Fe, but not in plants grown with high levels of Fe. However, it is still an open question as to how Fe acts as an inhibitor and which pool of Fe (e.g., root, phloem, etc.) in the plant acts as the key regulator for gene expression control. To further clarify this, we studied the effect of the foliar application of Fe on the expression of Fe-acquisition genes in several Strategy I plants, including wild-type cultivars of Arabidopsis [Arabidopsis                 thaliana (L.) Heynh], pea [Pisum sativum L.], tomato [Solanum lycopersicon Mill.], and cucumber [Cucumis sativus L.], as well as mutants showing constitutive expression of Fe-acquisition genes when grown under Fe-sufficient conditions [Arabidopsis opt3-2 and frd3-3, pea dgl and brz, and tomato chln (chloronerva)]. The results showed that the foliar application of Fe blocked the expression of Fe-acquisition genes in the wild-type cultivars and in the frd3-3, brz, and chln mutants, but not in the opt3-2 and dgl mutants, probably affected in the transport of a Fe-related repressive signal in the phloem. Moreover, the addition of either ACC (ethylene precursor) or GSNO (NO donor) to Fe-deficient plants up-regulated the expression of Fe-acquisition genes, but this effect did not occur in Fe-deficient plants sprayed with foliar Fe, again suggesting the existence of a Fe-related repressive signal moving from leaves to roots.
authors.affiliation: Department of Botany, Ecology and Plant Physiology, Edificio Celestino Mutis C-4, Campus de Rabanales, University of Córdoba, 14014 Córdoba, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: García
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Romera
authors.forename: Minviluz G
authors.initials: MG
authors.lastname: Stacey
authors.forename: Gary
authors.initials: G
authors.lastname: Stacey
authors.forename: Eduardo
authors.initials: E
authors.lastname: Villar
authors.forename: Esteban
authors.initials: E
authors.lastname: Alcántara
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-Vicente
mesh_terms: D000598:Amino Acids, Cyclic / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D027682:Cation Transport Proteins / Q000235:genetics; D018553:Cucumis sativus / Q000235:genetics / Q000378:metabolism; D038181:FMN Reductase / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics*; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D020030:Nitric Oxide Donors / Q000494:pharmacology; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D026422:S-Nitrosoglutathione / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D000598:Amino Acids, Cyclic; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D027682:Cation Transport Proteins; D038181:FMN Reductase; D007501:Iron; D020030:Nitric Oxide Donors; D026422:S-Nitrosoglutathione; C501411:FIT1 protein, Arabidopsis; C099651:IRT1 protein, Arabidopsis; C023863:1-aminocyclopropane-1-carboxylic acid; C023903:ferric citrate iron reductase