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The nitrate transporter family protein LjNPF8.6 controls the N-fixing nodule activity

Totev Valkov V., Rogato A., Martins Alves L., Sol S., Noguero M., Leran S., Lacombe B., Chiurazzi M.. 2017. Plant Physiology, 175 : p. 1269-1282.

DOI: 10.1104/pp.17.01187

N-fixing nodules are new organs formed on legume roots as a result of the beneficial interaction with soil bacteria, rhizobia. The nodule functioning is still a poorly characterized step of the symbiotic interaction, as only a few of the genes induced in N-fixing nodules have been functionally characterized. We present here the characterization of a member of the Lotus japonicus nitrate transporter1/peptide transporter family, LjNPF8.6. The phenotypic characterization carried out in independent L. japonicus LORE1 insertion lines indicates a positive role of LjNPF8.6 on nodule functioning, as knockout mutants display N-fixation deficiency (25%) and increased nodular superoxide content. The partially compromised nodule functioning induces two striking phenotypes: anthocyanin accumulation already displayed 4 weeks after inoculation and shoot biomass deficiency, which is detected by long-term phenotyping. LjNPF8.6 achieves nitrate uptake in Xenopus laevis oocytes at both 0.5 and 30 mm external concentrations, and a possible role as a nitrate transporter in the control of N-fixing nodule activity is discussed.

Mots-clés : fixation de l'azote; bactérie fixatrice de l'azote; rhizobium; lotus; formation de nodosités; nitrogen fixation genes [en]; xenopus laevis; nitrate; lotus japonicus

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