Antioxidative response to salinity in soybean leaves: the role of heme oxygenase.

BALESTRASSE, KARINA B.; ZILLI, CARLA G.; NORIEGA, GUILLERMO O.; SANTA-CRUZ, DIEGO M.; TOMARO, MARÍA L.

Mar del Plata, Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

In plant cells, salinity causes the induction of the endogeneous synthesis of reactive oxygen species. Oxidative stress parameters were analysed in soybean leaves subjected to different NaCl concentrations (0, 50 and 200 mM). Loss of chlorophyll content as well as the enhancement of ion leakage and TBARS formation were only evidenced under 200 mM NaCl treatment. Accumulation of hydrogen peroxide and superoxide anion were tested in situ by histochemical methods. While treatment with 100mM NaCl caused an enhancement of catalase activity respect to controls, no difference was observed under 50 mM NaCl, and an inhibition (33%) was detected in 200 mM NaCl treated plants. Superoxide dismutase activity was augmented under 50 mM NaCl treatment, no differences were observed under 100 mM NaCl and 200 mM NaCl caused a diminution in both parameters. RT-PCR analysis revealed that all these activities were positive correlated with gene expressions. Heme oxygenase (HO) is involved in heme degradation and participates in the antioxidant machinery of the cells. Our results indicate that HO activity, protein synthesis and gene expression were significantly increased under 50 and 100 mM NaCl, whereas no differences were observed under 200 mM NaCl. These findings indicate that, under salinity, heme catabolism is up-regulated as a means of defence against oxidative injury.