Haem oxygenase and catalase behaviour in soybean nodules and roots as a response to cadmiun treatment

BALESTRASSE, K; YANNARELLI, G; SANTA CRUZ, D; NORIEGA, GO; TOMARO, ML; BATLLE, A

Salve Regina University, Newport, Rhode Island, USA

Congreso; Gordon Research Conferences 2006. Chemistry and Biology of Tetrapyrroles; 2006

Haem oxygenase (HO EC 1.14.99.3) catalyses the oxidative conversion of haem to biliverdin IXá (BV) with the concomitant released of carbon monoxide and iron. HO has attracted particular interest in mammal tissues as it is finely up-regulated by stress conditions and generates products that might have important biological activities. Our goal was to study the expressions of haem oxygenase-1 (HO-1) and catalase (CAT, EC 1.11.1.6) genes in nodules and roots of soybean plants treated with Cd. Treatment with 200 ìM Cd caused the up-regulation of HO-1, as well as a 100% enhancement of its activity in the nodules. On the other hand, a down regulation occurred in the roots (40%). While in the nodules there was an augmentation in the transcript levels of CAT (25%), an important diminution (50%) was found in the roots. The changes observed in the messenger levels were also found in the protein levels and activities. These data let us suppose that in the nodules an induction of HO-1 occurred as a signal of cell protection against oxidative damage and CAT was also up-regulated to safeguard normal cellular functions and survival. In the roots, treatment with 200 ìM Cd inhibited CAT activity (56%) and produced down-regulation in protein and transcript expression. These results could be explaining our previous findings suggesting that oxidative stress produced by Cd treatment was more pronounced in roots than in nodules of soybean plants.