title: Heme oxygenase up-regulation in ultraviolet-B irradiated soybean plants involves reactive oxygen species.
abstract: Ultraviolet-B (UV-B) radiation has a negative impact on plant cells, and leads to the generation of reactive oxygen species (ROS). Heme oxygenase (HO, EC 1.14.99.3) plays a protective role against oxidative stress in mammals, but little is known about this issue in plants. Here, we report for the first time the response of HO 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. Treatment with 30 kJ m(-2) UV-B provoked a decrease in these antioxidant enzyme activities. Immunoblot analysis showed a 4.3 and 3.7-fold increase in HO-1 protein expression after irradiation with 7.5 and 15 kJ m(-2), respectively. HO-1 transcript levels were enhanced (up to 77%) at these doses, as assessed by semi-quantitative RT-PCR. These data demonstrated that increased HO activity was associated with augmented protein expression and transcript levels. 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. Our results indicate 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.
authors.affiliation: Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires, 1113, Argentina. gyanna@ffyb.uba.ar
authors.forename: Gustavo G
authors.initials: GG
authors.lastname: Yannarelli
authors.forename: Guillermo O
authors.initials: GO
authors.lastname: Noriega
authors.forename: Alcira
authors.initials: A
authors.lastname: Batlle
authors.forename: Maria L
authors.initials: ML
authors.lastname: Tomaro
mesh_terms: D060387:Ascorbate Peroxidases; D001205:Ascorbic Acid / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism / Q000528:radiation effects; D015870:Gene Expression; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism / Q000528:radiation effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000528:radiation effects; D010544:Peroxidases / Q000378:metabolism / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000528:radiation effects*; D013025:Glycine max / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014466:Ultraviolet Rays; D015854:Up-Regulation
chemical_list: D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D006419:Heme Oxygenase (Decyclizing); D001205:Ascorbic Acid