Mitochondrial ascorbate synthesis acts as a pro-oxidant pathway and down-regulate energy supply in plants

Attempts to improve the ascorbate (AsA) content of plants are still dealing with the limited understanding of why exists a wide variability of this powerful anti-oxidant molecule in different plant sources, species and environmental situations. In plant mitochondria, the last step of AsA synthesis i...

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Detalles Bibliográficos
Autores principales: Gonçalves de Oliveira, Jurandi, Mazorra Morales, Luis Miguel, Cosme Silva, Gláucia Michelle, Bortolini Santana, Diederson, Pireda, Saulo, Dorighetto Cogo, Antônio Jesus, Schuabb Heringer, Angelo, Reis de Oliveira, Tadeu dos, Souza Reis, Ricardo, Prado, L. A. S., Vicente de Oliveira, André, Silveira, Vanildo, Da Cunha, Maura, Barros, C. F., Rocha Façanha, Arnoldo, Baldet, P., Bartoli, Carlos Guillermo, Gomes da Silva, Marcelo
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2019
Materias:
Ciencias Agrarias
ascorbate
plant mitochondria
oxidant
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/125627
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
Descripción
Sumario:Attempts to improve the ascorbate (AsA) content of plants are still dealing with the limited understanding of why exists a wide variability of this powerful anti-oxidant molecule in different plant sources, species and environmental situations. In plant mitochondria, the last step of AsA synthesis is catalyzed by the enzyme L-galactone-1,4-lactone dehydrogenase (L-GalLDH). By using GalLDH-RNAi silencing plant lines, biochemical and proteomic approaches, we here discovered that, in addition to accumulate this antioxidant, mitochondria synthesize AsA to down-regulate the respiratory activity and the cellular energy provision. The work reveals that the AsA synthesis pathway within mitochondria is a branched electron transfer process that channels electrons towards the alternative oxidase, interfering with conventional electron transport. It was unexpectedly found that significant hydrogen peroxide is generated during AsA synthesis, which affects the AsA level. The induced AsA synthesis shows proteomic alterations of mitochondrial and extra-mitochondrial proteins related to oxidative and energetic metabolism. The most identified proteins were known components of plant responses to high light acclimation, programmed cell death, oxidative stress, senescence, cell expansion, iron and phosphorus starvation, different abiotic stress/pathogen attack responses and others. We propose that changing the electron flux associated with AsA synthesis might be part of a new mechanism by which the L-GalLDH enzyme would adapt plant mitochondria to fluctuating energy demands and redox status occurring under different physiological contexts.

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