title: Hypoxia and bicarbonate could limit the expression of iron acquisition genes in Strategy I plants by affecting ethylene synthesis and signaling in different ways.
abstract: In a previous work, it was shown that bicarbonate (one of the most important factors causing Fe chlorosis in Strategy I plants) can limit the expression of several genes involved in Fe acquisition. Hypoxia is considered another important factor causing Fe chlorosis, mainly on calcareous soils. However, to date it is not known whether hypoxia aggravates Fe chlorosis by affecting bicarbonate concentration or by specific negative effects on Fe acquisition. Results found in this work show that hypoxia, generated by eliminating the aeration of the nutrient solution, can limit the expression of several Fe acquisition genes in Fe-deficient Arabidopsis, cucumber and pea plants, like the genes for ferric reductases AtFRO2, PsFRO1 and CsFRO1; iron transporters AtIRT1, PsRIT1 and CsIRT1; H(+) -ATPase CsHA1; and transcription factors AtFIT, AtbHLH38, and AtbHLH39. Interestingly, the limitation of the expression of Fe-acquisition genes by hypoxia did not occur in the Arabidopsis ethylene constitutive mutant ctr1, which suggests that the negative effect of hypoxia is related to ethylene, an hormone involved in the upregulation of Fe acquisition genes. As for hypoxia, results obtained by applying bicarbonate to the nutrient solution suggests that ethylene is also involved in its negative effect, since ACC (1-aminocyclopropane-1-carboxylic acid; ethylene precursor) partially reversed the negative effect of bicarbonate on the expression of Fe acquisition genes. Taken together, the results obtained show that hypoxia and bicarbonate could induce Fe chlorosis by limiting the expression of Fe acquisition genes, probably because each factor negatively affects different steps of ethylene synthesis and/or signaling.
authors.affiliation: Department of Botany, Ecology and Plant Physiology, Edificio Celestino Mutis (C-4), Campus de Rabanales, University of Córdoba, 14071, Córdoba, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: García
authors.forename: María J
authors.initials: MJ
authors.lastname: García-Mateo
authors.forename: Carlos
authors.initials: C
authors.lastname: Lucena
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Romera
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Rojas
authors.forename: Esteban
authors.initials: E
authors.lastname: Alcántara
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-Vicente
mesh_terms: D017360:Arabidopsis; D001639:Bicarbonates / Q000378:metabolism*; D018553:Cucumis sativus / Q000235:genetics; D005030:Ethylenes / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000378:metabolism*; D010100:Oxygen / Q000502:physiology*; D018532:Pisum sativum / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
chemical_list: D001639:Bicarbonates; D005030:Ethylenes; C036216:ethylene; D007501:Iron; D010100:Oxygen