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Begara-Morales J.C.,University of Jaén | Chaki M.,Molecular and Cellular Biology of Plants | Sanchez-Calvo B.,University of Jaén | Mata-Perez C.,University of Jaén | And 4 more authors.
Journal of Experimental Botany | Year: 2013

Protein tyrosine nitration is a post-translational modification mediated by reactive nitrogen species (RNS) that is associated with nitro-oxidative damage. No information about this process is available in relation to higher plants during development and senescence. Using pea plants at different developmental stages (ranging from 8 to 71 days), tyrosine nitration in the main organs (roots, stems, leaves, flowers, and fruits) was analysed using immunological and proteomic approaches. In the roots of 71-day-old senescent plants, nitroproteome analysis enabled the identification a total of 16 nitrotyrosine-immunopositive proteins. Among the proteins identified, NADP-isocitrate dehydrogenase (ICDH), an enzyme involved in the carbon and nitrogen metabolism, redox regulation, and responses to oxidative stress, was selected to evaluate the effect of nitration. NADP-ICDH activity fell by 75% during senescence. Analysis showed that peroxynitrite inhibits recombinant cytosolic NADP-ICDH activity through a process of nitration. Of the 12 tyrosines present in this enzyme, mass spectrometric analysis of nitrated recombinant cytosolic NADP-ICDH enabled this study to identify the Tyr392 as exclusively nitrated by peroxynitrite. The data as a whole reveal that protein tyrosine nitration is a nitric oxide-derived PTM prevalent throughout root development and intensifies during senescence. © 2013 The Authors.

Garcia-Abellan J.O.,CSIC - Center of Edafology and Applied Biology of the Segura | Egea I.,CSIC - Center of Edafology and Applied Biology of the Segura | Pineda B.,Laboratory of Biotechnological Breeding | Sanchez-Bel P.,CSIC - Center of Edafology and Applied Biology of the Segura | And 6 more authors.
Physiologia Plantarum | Year: 2014

For salt tolerance to be achieved in the long-term plants must regulate Na+/K+ homeostasis over time. In this study, we show that the salt tolerance induced by overexpression of the yeast HAL5 gene in tomato (Solanum lycopersicum) was related to a lower leaf Na+ accumulation in the long term, by reducing Na+ transport from root to shoot over time regardless of the severity of salt stress. Furthermore, maintaining Na+/K+ homeostasis over time was associated with changes in the transcript levels of the Na+ and K+ transporters such as SlHKT1;2 and SlHAK5. The expression of SlHKT1;2 was upregulated in response to salinity in roots of transgenic plants but downregulated in the roots of wild-type (WT) plants, which seems to be related to the lower Na+ transport rate from root to shoot in transgenic plants. The expression of the SlHAK5 increased in roots and leaves of both WT and transgenic plants under salinity. However, this increase was much higher in the leaves of transgenic plants than in those of WT plants, which may be associated with the ability of transgenic leaves to maintain Na+/K+ homeostasis over time. Taken together, the results show that the salt tolerance mechanism induced by HAL5 overexpression in tomato is related to the appropriate regulation of ion transport from root to shoot and maintenance of the leaf Na+/K+ homeostasis through modulation of SlHKT1 and SlHAK5 over time. © 2014 Scandinavian Plant Physiology Society.

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