Involvement of Heme Oxygenase as Antioxidant Defense in Soybean Nodules

BALESTRASSE KB; NORIEGA GO; BATLLE A; TOMARO ML

FREE RADICAL RESEARCH

Taylor & Francis

Año: 2005 vol. 39 p. 145 - 151

1071-5762

Objective:We have previously demonstrated that the inducible formof 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. Materials and methods: Four-weeks-old soybean nodulated plants were treated with different cadmium chloride concentrations (0, 50 and 200mMÞ 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 analized. Results: Treatment with 200mMCd during 48 h caused a 67% increase in TBARS content, whereas GSHdecreased 44%, and total superoxidedismutase, gluthatione reductase and guaiacol peroxidasewere also inhibited 54, 20 and 60%, respectively.Atotal of 200mM Cd produced the overexpression of heme oxygenase-1, as well as a 10-fold enhancement of its activity. Co-administration of biliverdin ð10mMÞ completely prevented the effects caused byCd.Treatmentwith Zn protoporphyrin IX, a strong inhibitor of heme oxygenase, expectedly decreased hemeoxygenase-1 activity to half.When the inhibitorwas given together with Cd, completely prevented the enzyme induction and oxidative stress parameters were significantly enhanced. Conclusion:Taking together, these results are indicating that heme oxygenase plays a protective role against oxidative cell damage in soybean nodules