Heme oxygenase up-regulation in UV-B irradiated soybean plants involves reactive oxygen species

YANNARELLI, G.; NORIEGA G.O.; SANTA CRUZ, DM; BATLLE, A.; TOMARO, M.L

Rosario, Argentina

Congreso; XLII Reunión Anual Científica de la Sociedad Argentina de Bioquímica y Biología Molecular; 2006

We have previously reported that heme oxygenase (HO) plays a protective role against oxidative stress in plants, as it occurs in mammal tissues. In the present study we investigated the mechanism of HO-1 up-regulation in leaves of soybean (Glycine max L.) plants subjected to UV-B radiation. Under 7.5 and 15 kJ m-2 UV-B doses, HO, catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) activities were increased and the production of thiobarbituric acid reactive substances (TBARS) regain control values after 4 h of plant recuperation. Semi-quantitative RT-PCR demonstrated an enhancement of HO-1 transcript levels (77%), while protein expression, assessed by Western-blotting, increased up to 4-fold respect to controls. Plants pre-treated with the antioxidant ascorbic acid did not show the UV-B-induced up-regulation of HO-1 mRNA, but hydrogen peroxide treatment could mimic this reaction. Treatment with 30 kJ m-2 UV-B diminished the antioxidant enzyme activities and provoked a significant decrease in HO-1 transcript levels as a result of ROS overproduction. Our data indicates that HO is up-regulated in a dose depending manner as a mechanism of cell protection against oxidative damage and that such response occurred as a consequence of HO-1 mRNA enhancement involving ROS.