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Cornejo Ibergallartu, Alfonso

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Cornejo Ibergallartu

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Alfonso

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Ciencias

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InaMat2. Instituto de InvestigaciĆ³n en Materiales Avanzados y MatemĆ”ticas

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0000-0001-8810-0062

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2417

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Now showing 1 - 2 of 2
  • PublicationOpen Access
    Tryptophan levels as a marker of auxins and nitric oxide signaling
    (MDPI, 2022) LĆ³pez GĆ³mez, Pedro; Smith, Edward N.; Bota, Pedro; Cornejo Ibergallartu, Alfonso; Urra RodrĆ­guez, Marina; Buezo Bravo, Javier; MorĆ”n Juez, JosĆ© Fernando; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Institute for Multidisciplinary Research in Applied Biology - IMAB; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad PĆŗblica de Navarra / Nafarroako Unibertsitate Publikoa
    The aromatic amino acid tryptophan is the main precursor for indole-3-acetic acid (IAA), which involves various parallel routes in plants, with indole-3-acetaldoxime (IAOx) being one of the most common intermediates. Auxin signaling is well known to interact with free radical nitric oxide (NO) to perform a more complex effect, including the regulation of root organogenesis and nitrogen nutrition. To fathom the link between IAA and NO, we use a metabolomic approach to analyze the contents of low-molecular-mass molecules in cultured cells of Arabidopsis thaliana after the application of S-nitrosoglutathione (GSNO), an NO donor or IAOx. We separated the crude extracts of the plant cells through ion-exchange columns, and subsequent fractions were analyzed by gas chromatography-mass spectrometry (GC-MS), thus identifying 26 compounds. A principal component analysis (PCA) was performed on N-metabolism-related compounds, as classified by the Kyoto Encyclopedia of Genes and Genomes (KEGG). The differences observed between controls and treatments are mainly explained by the differences in Trp contents, which are much higher in controls. Thus, the Trp is a shared response in both auxin- and NO-mediated signaling, evidencing some common signaling mechanism to both GSNO and IAOx. The differences in the low-molecularmass- identified compounds between GSNO- and IAOx-treated cells are mainly explained by their concentrations in benzenepropanoic acid, which is highly associated with IAA levels, and salicylic acid, which is related to glutathione. These results show that the contents in Trp can be a marker for the study of auxin and NO signaling.
  • PublicationEmbargo
    A new oxidative pathway of nitric oxide production from oximes in plants
    (Cell Press, 2024) LĆ³pez GĆ³mez, Pedro; Buezo Bravo, Javier; Urra RodrĆ­guez, Marina; Cornejo Ibergallartu, Alfonso; Esteban Terradillos, Raquel; FernĆ”ndez de los Reyes, Jorge; Urarte RodrĆ­guez, EstĆ­baliz; RodrĆ­guez-Dobreva, EstefanĆ­a; Chamizo Ampudia, Alejandro; Eguaras, Alejandro; Wolf, Sebastian; Marino Bilbao, Daniel; MartĆ­nez Merino, VĆ­ctor; MorĆ”n Juez, JosĆ© Fernando; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute for Advanced Materials and Mathematics - INAMAT2
    Nitric oxide (NO) is an essential reactive oxygen species and a signal molecule in plants. Although several studies have proposed the occurrence of oxidative NO production, only reductive routes for NO production, such as the nitrate (NO-3) -upper-reductase pathway, have been evidenced to date in land plants. However, plants grown axenically with ammonium as the sole source of nitrogen exhibit contents of nitrite and NO3, evidencing the existence of a metabolic pathway for oxidative production of NO. We hypothesized that ox- imes, such as indole-3-acetaldoxime (IAOx), a precursor to indole-3-acetic acid, are intermediate oxidation products in NO synthesis. We detected the production of NO from IAOx and other oximes catalyzed by peroxidase (POD) enzyme using both 4-amino-5-methylamino-20,70-difluorescein fluorescence and chem- iluminescence. Flavins stimulated the reaction, while superoxide dismutase inhibited it. Interestingly, mouse NO synthase can also use IAOx to produce NO at a lower rate than POD. We provided a full mech- anism for POD-dependent NO production from IAOx consistent with the experimental data and supported by density functional theory calculations. We showed that the addition of IAOx to extracts from Medicago truncatula increased the in vitro production of NO, while in vivo supplementation of IAOx and other oximes increased the number of lateral roots, as shown for NO donors, and a more than 10-fold increase in IAOx dehydratase expression. Furthermore, we found that in vivo supplementation of IAOx increased NO pro- duction in Arabidopsis thaliana wild-type plants, while prx33-34 mutant plants, defective in POD33-34, had reduced production. Our data show that the release of NO by IAOx, as well as its auxinic effect, explain the superroot phenotype. Collectively, our study reveals that plants produce NO utilizing diverse molecules such as oximes, POD, and flavins, which are widely distributed in the plant kingdom, thus intro- ducing a long-awaited oxidative pathway to NO production in plants. This knowledge has essential impli- cations for understanding signaling in biological systems.