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 - 3 of 3
  • PublicationOpen Access
    Increased ascorbate biosynthesis does not improve nitrogen fixation nor alleviate the effect of drought stress in nodulated Medicago truncatula plants
    (Frontiers Media, 2021) Cobos Porras, Inmaculada Libertad; Rubia Galiano, María Isabel; Huertas, Raúl; Kum, David; Dalton, David A.; Udvardi, Michael; Arrese-Igor Sánchez, César; Larrainzar Rodríguez, Estíbaliz; Institute for Multidisciplinary Research in Applied Biology - IMAB; Gobierno de Navarra / Nafarroako Gobernua, PC112-113 LEGUSI
    Legume plants are able to establish nitrogen-fixing symbiotic relations with Rhizobium bacteria. This symbiosis is, however, affected by a number of abiotic constraints, particularly drought. One of the consequences of drought stress is the overproduction of reactive oxygen (ROS) and nitrogen species (RNS), leading to cellular damage and, ultimately, cell death. Ascorbic acid (AsA), also known as vitamin C, is one of the antioxidant compounds that plants synthesize to counteract this oxidative damage. One promising strategy for the improvement of plant growth and symbiotic performance under drought stress is the overproduction of AsA via the overexpression of enzymes in the Smirnoff-Wheeler biosynthesis pathway. In the current work, we generated Medicago truncatula plants with increased AsA biosynthesis by overexpressing MtVTC2, a gene coding for GDP-L-galactose phosphorylase. We characterized the growth and physiological responses of symbiotic plants both under well-watered conditions and during a progressive water deficit. Results show that increased AsA availability did not provide an advantage in terms of plant growth or symbiotic performance either under well-watered conditions or in response to drought.
  • PublicationOpen Access
    Drought stress modifies the source-sink dynamics of nitrogen-fixing soybean plants prioritizing roots and nodules
    (Wiley, 2025-05-26) Rubia Galiano, María Isabel; Larrainzar Rodríguez, Estíbaliz; Arrese-Igor Sánchez, César; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Soybean plants are one of the most cultivated legume crops worldwide. Their ability to establish nitrogen-fixing symbiosis with rhizobium bacteria allows the reduction of molecular nitrogen to ammonium, contributing to a reduction in the dependence on nitrogen fertilizers. However, nitrogen fixation is highly sensitive to environmental stresses, such as water deficit, and the regulatory mechanisms underlying this inhibition remain debatable. In the current study, we analyzed carbon (C) allocation dynamics in drought-stressed soybean plants following the application of [U-C-13]-sucrose to source leaves. Three sets of plants were analyzed: well-watered plants, mild drought, and severe drought-stressed plants. C-13 distribution was monitored for up to 6 h post-application. Under optimal water conditions, C-13 was mainly allocated to young (sink) leaves. During drought stress, transport trends changed, prioritizing C allocation primarily to the roots and nodules to a lesser extent. Metabolite profiling identified drought- and tissue-specific variations in the levels of the major C and N compounds.
  • PublicationOpen Access
    A novel biosensor to monitor proline in pea root exudates and nodules under osmotic stress and recovery
    (Springer, 2020) Rubia Galiano, María Isabel; Ramachandran, Vinoy K.; Arrese-Igor Sánchez, César; Larrainzar Rodríguez, Estíbaliz; Poole, Philip S.; Institute for Multidisciplinary Research in Applied Biology - IMAB
    Background and aims: Plant and bacteria are able to synthesise proline, which acts as a compound to counteract the negative effects of osmotic stresses. Most methodologies rely on the extraction of compounds using destructive methods. This work describes a new proline biosensor that allows the monitoring of proline levels in a non-invasive manner in root exudates and nodules of legume plants. Methods: The proline biosensor was constructed by cloning the promoter region of pRL120553, a gene with high levels of induction in the presence of proline, in front of the lux cassette in Rhizobium leguminosarum bv. viciae. Results: Free-living assays show that the proline biosensor is sensitive and specific for proline. Proline was detected in both root exudates and nodules of pea plants. The luminescence detected in bacteroids did not show variations during osmotic stress treatments, but significantly increased during recovery. Conclusions: This biosensor is a useful tool for the in vivo monitoring of proline levels in root exudates and bacteroids of symbiotic root nodules, and it contributes to our understanding of the metabolic exchange occurring in nodules under abiotic stress conditions.