Expression of pea cytosolic thioredoxins under oxidative stress induced by copper

CODÓ, P., PETÓN, A., MONTI, S., BARRETO, J., MERMOZ, J., FRUTOS R.J., PAGANO, E. AND WOLOSIUK, R.A.

Mar del Plata

Congreso; XLIII Reunión Nacional de la SAIB; 2007

Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular

Thioredoxins (Trx) are ubiquitous proteins that participate actively in tolerance to oxidative stress in procaryotes and cellular compartments of eucaryotes. Among the large number of isoforms found in subfamilies of plant tissues, the functions of cytosolic Trx-h isoforms are barely known. Therefore, we deemed it desirable to analyze the contribution of four pea Trx-h isoforms to the tolerance of the oxidative stress. To this end, we selected copper, a micronutrient essential for growth, as the environmental perturbant because high concentrations are extremely toxic due to the capacity to generate reactive oxygen species (ROS). Leaves from plants exposed to an excess of copper were analyzed for (a) the uptake of the cation, (b) the enzyme activities related to the detoxification of ROS and (c) the expression (RT-PCR) of the four pea isoforms of Trx-h. In these studies, we found higher levels of cooper intracellular concentrations, greater activities of antioxidant enzymes and differential expression of the Trx-h isoforms. But more importantly, the treatment with the cation increased transcript levels of Trx-h1 and Trx-h2 while those of Trx-h3 and Trx-h4 did not show significant changes. These results are in line with the view that isoforms of cytosolic Trx-h in pea leaves play specific roles during oxidative stress