Increased tolerance to oxidative stress in plants expressing in vivo substrate amplification system

GIRÓ, MARIANA; CECCOLI, ROMINA; CARRILLO, NÉSTOR; LODEYRO, ANABELLA F.

San Luis

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Ferredoxin NADP+-reductase (FNR) and ferredoxin constitute the reducing side of photosystem I, producing the necessary NADPH for productive chloroplasts routes. Oxidative stress causes ferredoxin down-regulation and NADP+ shortage, leading to over-reduction of the photosynthetic electron transport chain and reactive oxygen species generation. Expression of cyanobacterial flavodoxin in tobacco chloroplasts compensates for ferredoxin decline and enhances tolerance to oxidative stress. We postulate that higher degrees of tolerance could be achieved by improving the capacity for flavodoxin reduction in planta under stress conditions. Soluble FNR catalyzes flavodoxin reduction by NADPH with high efficiency. Plants expressing a soluble cyanobacterial FNR, a modified version of the reductase in which the phycobilisome binding domain has been removed, were generated and crossed with those expressing flavodoxin. Co-expression of the two flavoproteins resulted in lines displaying enhanced tolerance to redox-cycling oxidants, lower damage to pigments and membranes, and decreased reactive oxygen species accumulation, generating an in vivo amplification system to optimise flavodoxin reduction under stress conditions. The results provide a tool to improve crop tolerance toward environmental hardships.