@misc{10481/106533,
year = {2025},
month = {11},
url = {https://hdl.handle.net/10481/106533},
abstract = {Legumes form symbioses with nitrogen-fixing bacteria, well studied metabolically but less so in terms of
respiration. Symbiotic nitrogen fixation demands high respiratory ATP and carbon skeletons, linking nitrogen
assimilation and both NADH- and ATP-dependent process to mitochondrial respiration. The plant mitochondrial
electron transport chain contains two terminal oxidases that differentially fractionate against 18O, providing
estimations in vivo of the energy efficiency of respiration. The regulation of N2 fixation by plant respiratory
parameters remains unknown. To investigate the regulatory interactions of these two metabolic processes, we
tested the effect of different plant N status and sources on respiratory parameters and nutrition in Lotus japonicus.
Plants were grown with two levels of KNO3 fertilization (5 mM and 25 mM) and with the N2 fixing symbiotic
bacteria Mesorhizobium loti, which induced the formation of root nodules (NP). Additionally, we characterized
roots containing non-fixing nodules by growing plants that display spontaneous nodule formation (snf) (SNF). We
evaluated the natural abundances of 13C and 15N, and 18O discrimination during respiration in leaves and roots
using isotope-ratio mass spectrometry. NADH and nutrient content were measured using ultra-performance
liquid chromatography and inductively coupled plasma spectrometry. We observed that cytochrome c oxidase
activity was higher in nodulated roots capable of nitrogen fixation than in plants fertilized with high availability
of nitrate, and that nitrogen status strongly associates to respiratory parameters. These findings highlight the role
of cytochrome c oxidase in meeting the carbon and energy demands of symbiotic nitrogen fixation.},
organization = {ANID Fondecyt (Regular N◦ 1191118 and
1211473)},
organization = {Chilean Scholarship (2017–21180329)},
organization = {Spanish Ministerio de Ciencia, Innovacion y Universidades - AEI - European Union ‘NextGenerationEU’ -
(RYC2023-044592-I)},
publisher = {Elsevier},
keywords = {Nitrogen fixation},
keywords = {Respiration},
keywords = {Mass spectrometry},
title = {Nitrogen source and availability associate to mitochondrial respiratory pathways and symbiotic function in Lotus japonicus},
doi = {10.1016/j.jplph.2025.154606},
author = {Ortiz, José and Sanhueza, Carolina and Romero-Munar, Antonia and Sierra, Sandra and Palma Martín, Francisco José and Aroca, Ricardo and Coba de la Peña, Teodoro and López Gómez, Miguel and Bascuñan Godoy, Luisa and Fernández Del-Saz, Néstor},
}