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

• Published in: Journal of integrative plant biology 2016-08, Vol.58 (8), p.737-748
• Main Authors: Lima‐Melo, Yugo, Carvalho, Fabricio E. L., Martins, Márcio O., Passaia, Gisele, Sousa, Rachel H. V., Neto, Milton C. Lima, Margis‐Pinheiro, Márcia, Silveira, Joaquim A. G.
• Format: Article
• Language: English
• Subjects: Biomass; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Membrane - radiation effects; CO2 assimilation; Gases - metabolism; Gene Silencing - drug effects; Gene Silencing - radiation effects; Glutathione - metabolism; glutathione peroxidase; Glutathione Peroxidase - metabolism; Hydrogen Peroxide - metabolism; Light; Lipid Peroxidation - drug effects; Lipid Peroxidation - radiation effects; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondria - radiation effects; Oryza - drug effects; Oryza - physiology; Oryza - radiation effects; Oryza sativa; Oxidative Stress - drug effects; Oxidative Stress - radiation effects; Phenotype; photochemistry; Photosynthesis - drug effects; Photosynthesis - radiation effects; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant Leaves - radiation effects; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - metabolism; Plant Roots - radiation effects; redox homeostasis; Salinity; Sodium Chloride - pharmacology; Stress, Physiological - drug effects; Stress, Physiological - radiation effects
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.12464

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 GPX1 s line under non-stressful conditions, compared with non-transformed（NT） plants occurred in parallel to increased H_2O_2 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 H_2O_2 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 GPX1 s 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.