Overexpression of the mitochondrial PPR40 gene improves salt tolerance in Arabidopsis.

Mitochondrial respiration is sensitive to environmental conditions and can be influenced by abiotic stress. Previously we described the Arabidopsis mitochondrial pentatricopeptide repeat domain protein PPR40, and showed that the stress hypersensitive ppr40-1 mutant is compromised in mitochondrial electron transport (Zsigmond et al., 2008) [20]. Overexpression of the PPR40 gene in Arabidopsis resulted in enhanced germination and superior plant growth in saline conditions. Respiration increased in PPR40 overexpressing plants during salt stress. Reduced amount of hydrogen peroxide, diminished lipid peroxidation, lower ascorbate peroxidase and superoxide dismutase activity accompanied salt tolerance. Proline accumulation was enhanced in the ppr40-1 mutant, but unaltered in the PPR40 overexpressing plants. Our data suggest that PPR40 can diminish the generation of reactive oxygen species by stabilizing the mitochondrial electron transport and protecting plants via reducing oxidative damage during stress.