Tobacco plants overexpressing ferredoxin-NADP(H) reductases display enhanced stress tolerance

LODEYRO, ANABELLA FERNANDA; RODRIGUEZ VIRASORO, RAMIRO; GIRÓ, MARIANA; POLI, HUGO; VALLE, ESTELA MARTA; CARRILLO, NÉSTOR

Rosario, ARGENTINA

Congreso; XLII Reunion Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Ferredoxin-NADP(H) reductase (FNR) catalyses the last step of photosynthetic electron transport in chloroplasts, driving electrons from two molecules of ferredoxin to a single molecule of NADP+. Antisense tobacco plants with reduced amounts of FNR display diminished photosynthetic activity (Hajirezaei et al Plant J. (2002) 29:281) and enhanced photo-oxidative damage (Palatnik et al Plant J. (2003) 35:332). Furthermore, in response to oxidative stress Escherichia coli induces the expression of the flavoprotein FNR and its substrate flavodoxin (Krapp et alJ Bacteriol. (2002) 184:1474). In order to investigate if the overexpression of this enzyme improves oxidative stress tolerance in plants we prepared transgenic Nicotiana tabacum cv. Petit Havana plants expressing pea or cyanobacterial FNR from Anabaena PCC7119. In this work we evaluate the photosynthetic efficiency of the transgenic lines using fluorescence chlorophyll measurements, CO2 fixation rates and biomass accumulation. We found that FNR overexpression had no effect on growth or photosynthetic parameters. On the other hand, we studied tolerance to oxidative stress using high light treatments or redox-cycling herbicides that propagate reactive oxygen species, such as methyl viologen (MV). Interestingly, the transgenic plants with higher levels of the alien protein exhibited augmented tolerance to photooxidative damage and MV.