title: Immunolocalization of H(+)-ATPase and IRT1 enzymes in N(2)-fixing common bean nodules subjected to iron deficiency.
abstract: The demand for iron in leguminous plants increases during symbiosis, as the metal is utilised for the synthesis of various Fe-containing proteins in both plant and bacteroids. However, the acquisition of this micronutrient is problematic due to its low bioavailability at physiological pH under aerobic conditions. Induction of root Fe(III)-reductase activity is necessary for Fe uptake and can be coupled to the rhizosphere acidification capacity linked to the H(+)-ATPase activity. Fe uptake is related to the expression of a Fe(2+) transporter (IRT1). In order to verify the possible role of nodules in the acquisition of Fe directly from the soil solution, the localization of H(+)-ATPase and IRT1 was carried out in common bean nodules by immuno-histochemical analysis. The results showed that these proteins were particularly abundant in the central nitrogen-fixing zone of nodules, around the periphery of infected and uninfected cells as well as in the vascular bundle of control nodules. Under Fe deficiency an over-accumulation of H(+)-ATPase and IRT1 proteins was observed especially around the cortex cells of nodules. The results obtained in this study suggest that the increase in these proteins is differentially localized in nodules of Fe-deficient plants when compared to the Fe-sufficient condition and cast new light on the possible involvement of nodules in the direct acquisition of Fe from the nutrient solution.
authors.affiliation: Laboratoire des Plantes Extrêmophiles, Centre de Biotechnologie, Technopark de Borj Cedria, BP 901, Hammam Lif 2050, Tunisia. slatni_tarek@yahoo.fr
authors.forename: Tarek
authors.initials: T
authors.lastname: Slatni
authors.forename: Marta
authors.initials: M
authors.lastname: Dell'Orto
authors.forename: Imen
authors.initials: I
authors.lastname: Ben Salah
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Vigani
authors.forename: Abderrazak
authors.initials: A
authors.lastname: Smaoui
authors.forename: Houda
authors.initials: H
authors.lastname: Gouia
authors.forename: Graziano
authors.initials: G
authors.lastname: Zocchi
authors.forename: Chedly
authors.initials: C
authors.lastname: Abdelly
mesh_terms: D001692:Biological Transport; D027682:Cation Transport Proteins / Q000378:metabolism; D038181:FMN Reductase / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D005838:Genotype; D007150:Immunohistochemistry; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D009586:Nitrogen Fixation; D027805:Phaseolus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D042162:Rhizobium tropici / Q000502:physiology; D058441:Rhizosphere; D053204:Root Nodules, Plant / Q000378:metabolism; D013559:Symbiosis
chemical_list: D027682:Cation Transport Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D006180:Proton-Translocating ATPases