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Buezo Bravo, Javier

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https://academica-e.unavarra.es/handle/2454/48756

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Buezo Bravo

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Javier

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Ciencias

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IMAB. Research Institute for Multidisciplinary Applied Biology

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0000-0002-6287-1587

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811160

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Author: Esteban Terradillos, Raquel Ɨ Subject: Amine oxidase Ɨ

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    The importance of the urea cycle and its relationships to polyamine metabolism during ammonium stress in Medicago truncatula
    (Oxford University Press, 2022) Urra RodrĆ­guez, Marina; Buezo Bravo, Javier; Royo Castillejo, Beatriz; Cornejo Ibergallartu, Alfonso; LĆ³pez GĆ³mez, Pedro; CerdĆ”n Ruiz, Daniel; Esteban Terradillos, Raquel; MartĆ­nez Merino, VĆ­ctor; Gogorcena, Yolanda; Tavladoraki, Paraskevi; MorĆ”n Juez, JosĆ© Fernando; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Institute for Multidisciplinary Research in Applied Biology - IMAB; Ciencias; Universidad PĆŗblica de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernuaren
    The ornithineā€“urea cycle (urea cycle) makes a signifcant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants. High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity of copper amine oxidase, which releases ammonium from putrescine, was signifcantly decreased in both shoots and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cyclerelated proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important protective mechanisms limiting ammonium toxicity in M. truncatula. These fndings demonstrate the relevance of the urea cycle to polyamine metabolism in higher plants.