Symbiotic association between soybean plants and Bradyrhizobium japonicum develops oxidative stress and heme oxygenase-1 induction at early stages

ZILLI CG; SANTA- CRUZ DM; POLIZIO AH; TOMARO ML; BALESTRASSE KB

REDOX REPORT

MANEY PUBLISHING

Año: 2011 vol. 16 p. 49 - 55

1351-0002

We have previously demonstrated that the induction of heme oxygenase-1 (HO-1) (EC 1.14.99.3) plays aprotective role against oxidative stress in leaves and nodules of soybean plants subjected to cadmium,UV-B radiation, and salt stress. Here, we investigated HO-1, localization and their relationship withoxidative stress in different growth stages of soybean plants roots inoculated with Bradyrhizobiumjaponicum (3, 5, 7, 10, and 20 days post-inoculation) and nodules.After 7 days of inoculation, we observed a 70% increase in thiobarbituric acid-reactive substances thatcorrelates with an enhancement in the gene expression of HO-1, catalase, and superoxide dismutase.Furthermore, the inhibition of HO-1 activity by Zn-protoporphyrin IX produced an increase in lipidperoxidation and a decrease in glutathione content suggesting that, in this symbiotic process, HO-1 mayact as a signal molecule that protects the root against oxidative stress.We determined, for the first time, the tissular localization of HO-1 in nodules by electron-microscopeexamination. These results undoubtedly demonstrated that this enzyme is localized only in the plant tissueand its overexpression may play an important role as antioxidant defense in the plant. Moreover, wedemonstrate that, in roots, HO-1 is induced by oxidative stress produced by inoculation of B. japonicumand exerts an antioxidant response against it.