Involvement of heme oxygenase as antioxidant defense in soybean nodules.
OBJECTIVE
We have previously demonstrated that the inducible form of heme oxygenase plays a critical role in protecting against oxidative stress in mammals. To gain further insight into the functions of this enzyme in plants, we have tested its activity and expression in soybean nodules subjected to cadmium (Cd) stress.


METHODS
Four-weeks-old soybean nodulated plants were treated with different cadmium chloride concentrations (0, 50 and during 48 h. Oxidative stress parameters such as TBARS content, GSH levels and antioxidant enzyme activities were measured as well as heme oxygenase activity and expression. Besides, the effect of biliverdin and Zn-protophorphyrin IX were analyzed.


RESULTS
Treatment with 200 microM Cd during 48 h caused a 67% increase in TBARS content, whereas GSH decreased 44%, and total superoxide dismutase, gluthatione reductase and guaiacol peroxidase were also inhibited 54, 20 and 60%, respectively. A total of Cd produced the overexpression of heme oxygenase-1, as well as a 10-fold enhancement of its activity. Co-administration of biliverdin (10 microM) completely prevented the effects caused by Cd. Treatment with Zn protoporphyrin IX, a strong inhibitor of heme oxygenase, expectedly decreased heme oxygenase-1 activity to half. When the inhibitor was given together with Cd, completely prevented the enzyme induction and oxidative stress parameters were significantly enhanced.


CONCLUSIONS
Taking together, these results are indicating that heme oxygenase plays a protective role against oxidative cell damage in soybean nodules.
Balestrasse
Karina B
KB
Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956, Buenos Aires, Argentina.
Noriega
Guillermo O
GO
Batlle
Alcira
A
Tomaro
María L
ML
D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001664:Biliverdine / Q000494:pharmacology; D019256:Cadmium Chloride / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004798:Enzymes / Q000187:drug effects / Q000378:metabolism; D005978:Glutathione / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D051547:Heme Oxygenase-1; D018517:Plant Roots / Q000737:chemistry* / Q000187:drug effects / Q000201:enzymology; D011524:Protoporphyrins / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013025:Glycine max / Q000737:chemistry* / Q000187:drug effects / Q000201:enzymology; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D000975:Antioxidants; D004791:Enzyme Inhibitors; D004798:Enzymes; D011524:Protoporphyrins; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; C017803:zinc protoporphyrin; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D005978:Glutathione; D019256:Cadmium Chloride; D001664:Biliverdine