title: Local inhibition of nitrogen fixation and nodule metabolism in drought-stressed soybean.
abstract: Drought stress is a major factor limiting symbiotic nitrogen fixation (NF) in soybean crop production. However, the regulatory mechanisms involved in this inhibition are still controversial. Soybean plants were symbiotically grown in a split-root system (SRS), which allowed for half of the root system to be irrigated at field capacity while the other half remained water deprived. NF declined in the water-deprived root system while nitrogenase activity was maintained at control values in the well-watered half. Concomitantly, amino acids and ureides accumulated in the water-deprived belowground organs regardless of transpiration rates. Ureide accumulation was found to be related to the decline in their degradation activities rather than increased biosynthesis. Finally, proteomic analysis suggests that plant carbon metabolism, protein synthesis, amino acid metabolism, and cell growth are among the processes most altered in soybean nodules under drought stress. Results presented here support the hypothesis of a local regulation of NF taking place in soybean and downplay the role of ureides in the inhibition of NF.
authors.affiliation: Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, 31006 Pamplona, Spain.
authors.forename: Erena
authors.initials: E
authors.lastname: Gil-Quintana
authors.forename: Estíbaliz
authors.initials: E
authors.lastname: Larrainzar
authors.forename: Amaia
authors.initials: A
authors.lastname: Seminario
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: Díaz-Leal
authors.forename: Josefa M
authors.initials: JM
authors.lastname: Alamillo
authors.forename: Manuel
authors.initials: M
authors.lastname: Pineda
authors.forename: Cesar
authors.initials: C
authors.lastname: Arrese-Igor
authors.forename: Stefanie
authors.initials: S
authors.lastname: Wienkoop
authors.forename: Esther M
authors.initials: EM
authors.lastname: González
mesh_terms: D000596:Amino Acids / Q000032:analysis / Q000378:metabolism; D055864:Droughts; D009586:Nitrogen Fixation / Q000502:physiology*; D055170:Plant Root Nodulation / Q000502:physiology*; D018526:Plant Transpiration / Q000502:physiology; D040901:Proteomics; D013025:Glycine max / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D014508:Urea / Q000032:analysis / Q000378:metabolism
chemical_list: D000596:Amino Acids; D014508:Urea
keywords: Drought; N-feedback inhibition; local regulation; nitrogen fixation; proteomics; soybean; ureides.