J Integr Plant Biol. ›› 2016, Vol. 58 ›› Issue (8): 737-748.DOI: 10.1111/jipb.12464

Special Issue: Rice Genomics and Agriculture

• Molecular Physiology • Previous Articles     Next Articles

Mitochondrial GPX1 silencing triggers differential photosynthesis impairment in response to salinity in rice plants

Yugo Lima-Melo1, Fabricio E. L. Carvalho1, Márcio O. Martins1, Gisele Passaia2, Rachel H. V. Sousa1, Milton C. Lima Neto1, Márcia Margis-Pinheiro2 and Joaquim A. G. Silveira1*   

  1. 1Department of Biochemistry and Molecular Biology, Federal University of Ceará, CEP 60451-970, Fortaleza, Ceará, Brazil
    2Department of Genetics, Federal University of Rio Grande do Sul, CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
  • Received:2015-12-22 Accepted:2016-01-19 Published:2016-01-22
  • About author:*Correspondence: E-mail: silveira@ufc.br

Abstract:

The physiological role of plant mitochondrial glutathione peroxidases is scarcely known. This study attempted to elucidate the role of a rice mitochondrial isoform (GPX1) in photosynthesis under normal growth and salinity conditions. GPX1 knockdown rice lines (GPX1s) were tested in absence and presence of 100 mM NaCl for 6 d. Growth reduction of GPX1s line under non-stressful conditions, compared with non-transformed (NT) plants occurred in parallel to increased H2O2 and decreased GSH contents. These changes occurred concurrently with photosynthesis impairment, particularly in Calvin cycle's reactions, since photochemical efficiency did not change. Thus, GPX1 silencing and downstream molecular/metabolic changes modulated photosynthesis differentially. In contrast, salinity induced reduction in both phases of photosynthesis, which were more impaired in silenced plants. These changes were associated with root morphology alterations but not shoot growth. Both studied lines displayed increased GPX activity but H2O2 content did not change in response to salinity. Transformed plants exhibited lower photorespiration, water use efficiency and root growth, indicating that GPX1 could be important to salt tolerance. Growth reduction of GPX1s line might be related to photosynthesis impairment, which in turn could have involved a cross talk mechanism between mitochondria and chloroplast originated from redox changes due to GPX1 deficiency.

Key words: CO2 assimilation, glutathione peroxidase, Oryza sativa, photochemistry, redox homeostasis

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