title: Auxin: a major player in the shoot-to-root regulation of root Fe-stress physiological responses to Fe deficiency in cucumber plants.
abstract: The aim of this study was to investigate the effects of IAA and ABA in the shoot-to-root regulation of the expression of the main Fe-stress physiological root responses in cucumber plants subjected to shoot Fe functional deficiency. Changes in the expression of the genes CsFRO1, CsIRT1, CsHA1 and CsHA2 (coding for Fe(III)-chelate reductase (FCR), the Fe(II) transporter and H+-ATPase, respectively) and in the enzyme activity of FCR and the acidification capacity were measured. We studied first the ability of exogenous applications of IAA and ABA to induce these Fe-stress root responses in plants grown in Fe-sufficient conditions. The results showed that IAA was able to activate these responses at the transcriptional and functional levels, whereas the results with ABA were less conclusive. Thereafter, we explored the role of IAA in plants with or without shoot Fe functional deficiency in the presence of two types of IAA inhibitors, affecting either IAA polar transport (TIBA) or IAA functionality (PCIB). The results showed that IAA is involved in the regulation at the transcriptional and functional levels of both Fe root acquisition (FCR, Fe(II) transport) and rhizosphere acidification (H+-ATPase), although through different, and probably complementary, mechanisms. These results suggest that IAA is involved in the shoot-to-root regulation of the expression of Fe-stress physiological root responses.
authors.affiliation: CIPAV TimacAGRO International-Roullier Group, Polígono Arazuri-Orcoyen, c/C n° 32, 31160 Orcoyen, Navarra, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Bacaicoa
authors.forename: Verónica
authors.initials: V
authors.lastname: Mora
authors.forename: Angel María
authors.initials: AM
authors.lastname: Zamarreño
authors.forename: Marta
authors.initials: M
authors.lastname: Fuentes
authors.forename: Esther
authors.initials: E
authors.lastname: Casanova
authors.forename: José María
authors.initials: JM
authors.lastname: García-Mina
mesh_terms: D001692:Biological Transport; D002995:Clofibric Acid / Q000494:pharmacology; D018553:Cucumis sativus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D038181:FMN Reductase / Q000032:analysis; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D018520:Plant Shoots / Q000502:physiology*; D013312:Stress, Physiological; D014158:Transcription, Genetic; D014283:Triiodobenzoic Acids / Q000493:pharmacokinetics
chemical_list: D007210:Indoleacetic Acids; D014283:Triiodobenzoic Acids; D002995:Clofibric Acid; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; C052968:2,3,5-triiodobenzoic acid