Arrese-Igor Sánchez, César

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Arrese-Igor Sánchez

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César

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Ciencias

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IMAB. Research Institute for Multidisciplinary Applied Biology

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Now showing 1 - 2 of 2
  • PublicationOpen Access
    Insights into the regulation of nitrogen fixation in pea nodules: lessons from drought, abscisic acid and increased photoassimilate availability
    (EDP Sciences, 2001) González García, Esther; Gálvez, Loli; Royuela Hernando, Mercedes; Aparicio Tejo, Pedro María; Arrese-Igor Sánchez, César; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
    Nitrogen fixation in legume nodules has been shown to be very sensitive to drought and other environmental constraints. It has been widely assumed that this decline in nitrogen fixation was a consequence of an increase in the so-called oxygen diffusion barrier and a subsequent impairment to bacteroid respiration. However, it has been recently shown that nitrogen fixation is highly correlated with nodule sucrose synthase (SS) activity under drought and other environmental stresses. Whether this correlation reflects a causative relationship or not has not been proven yet. The evidence presented here suggests that SS controls nitrogen fixation under mild drought conditions. However, nitrogen fixation cannot be enhanced only by increasing glycolytic flux, as under these conditions nodules become oxygen limited. Abscisic acid also induces a decline in nitrogen fixation that is independent of SS. The overall results suggest the occurrence of a complex regulation of nodule nitrogen fixation involving, at least, both carbohydrate and oxygen fluxes within the nodule.
  • PublicationOpen Access
    Pea plant responsiveness under elevated [CO2] is conditioned by the N source (N2 fixation versus NO3 fertilization)
    (Elsevier, 2013) Aranjuelo Michelena, Iker; Cabrerizo Geijo, Pablo María; Arrese-Igor Sánchez, César; Aparicio Tejo, Pedro María; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
    The main goal of this study was to test the effect of [CO2] on C and N management in 2different plant organs (shoots, roots and nodules) and its implication in the 3responsiveness of exclusively N2-fixing and NO3--fed plants. For this purpose, 4exclusively N2-fixingand NO3--fed (10 mM) pea (Pisum sativumL.) plants were 5exposed to elevated [CO2] (1000 mol mol-1versus360 mol mol-1CO2). Gas 6exchange analyses, together with carbohydrate, nitrogen, total soluble proteins and 7amino acids were determined in leaves, roots and nodules. The data obtained revealed 8that although exposure to elevated [CO2] increased total dry mass (DM)in both N 9treatments, photosynthetic activity was down-regulated in NO3--fed plants, whereas N2-10fixing plants were capable of maintaining enhanced photosynthetic rates under elevated 11[CO2]. In the case of N2-fixing plants, the enhanced C sink strength of nodules enabled 12the avoidance of harmful leaf carbohydrate build up. On the other hand, in NO3--fed 13plants, elevated [CO2] caused a large increase in sucrose and starch. The increase in root 14DM did not contribute to stimulation ofC sinks in these plants. Although N2fixation 15matched plant N requirementswith the consequent increase in photosynthetic rates, in 16NO3--fed plants, exposure to elevated [CO2] negatively affected N assimilationwith the 17consequent photosynthetic down-regulation.