Mitochondrial ascorbate synthesis acts as a pro-oxidant pathway and down-regulate energy supply in plants
| Autor: | Luis Miguel Mazorra Morales, Angelo Schuabb Heringer, Jurandi Gonçalves de Oliveira, Maura Da Cunha, Gláucia Michelle Cosme Silva, Tadeu dos Reis de Oliveira, Claudia Franca Barros, Luis Alfredo dos Santos Prado, Ricardo Souza Reis, Antônio Jesus Dorighetto Cogo, André Vicente de Oliveira, Arnoldo Rocha Façanha, Pierre Baldet, Diederson Bortolini Santana, Marcelo Gomes da Silva, Vanildo Silveira, Carlos Guillermo Bartoli, Saulo Pireda |
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| Rok vydání: | 2019 |
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| Popis: | 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. Instituto de Fisiología Vegetal |
| Databáze: | OpenAIRE |
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