Biodegradation of 2,4-dinitrotoluene by transgenic tobacco plants expressing a bacterial flavodoxin

TOGNETTI VANESA B.; FILLAT M.; VALLE ESTELA M.; CARRILLO NESTOR; MONTI MARIELA R; SMANIA ANDREA M.

Bariloche-Argentina

Congreso; XXXIX Reunión Anual de SAIB; 2003

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Contamination of soil and groundwater at manufacturing sites with nitroaromatics such as 2,4-dinitrotoluene (DNT) poses serious environmental risks, since they are animal and human carcinogens. Flavodoxins (Fld) are small electron transfer flavoproteins present in bacteria and algae, but not in vascular plants. They are low-potential promiscuous electron carriers that can catalyse the NADPH-driven reduction of many aromatic compounds including nitroderivates. Since these chemicals are readily taken up by plants, we investigated whether transgenic tobacco expressing a bacterial Fld was able to degrade DNT more effectively than wild-type (wt) plants. Fld was targeted to chloroplasts (pfld) or cytosol (cfld) by Agrobacterium-mediated leaf disck transformation. Accumulation of the alien flavoprotein in chloroplasts, but not in the cytosol, resulted in augmented tolerance to DNT, with reduced symptoms of DNT toxicity and higher amounts of chlorophyll per fresh weight than in wt or in cfld lines. Pfld plants expressing high Fld levels removed more than 80% of DNT after 40 days of exposure. In contrast, susceptible lines mobilized less than 20% of the original amount of xenobiotic. These observations suggest that Fld expression in chloroplasts of transgenic tobacco plants allowed more effective detoxification of DNT, opening possibilities for their use in phytoremediation of contaminated sites.