REGULATION OF NITROGEN METABOLISM BY ANTIOXIDANT SYSTEM IN SOYBEAN PLANTS TREATED WITH SALT STRESS

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

Soja. Investigación científico-técnica desarrollada en el INBA (CONICET/FAUBA) y en la Facultad de Agronomía de la UBA

EDITORIAL FACULTAD DE AGRONOMÍA

Año: 2011; p. 92 - 98

The behaviour of enzymes involved in nitrogen metabolism, as well as oxidative stress generation andheme oxygenase gene expression, protein amount and activity, were analysed in soybean (Glycine maxL.) nodules exposed to 50, 100 and 200 mM NaCl concentrations. A significant increase in lipidperoxidation was found with 100 and 200 mM salt treatments. Moreover, superoxide dismutase,catalase and peroxidase activities were decreased under 100 and 200 mM salt. Nitrogenase activity andleghemeoglobin content were diminished and ammonium content increased only under 200 mM NaCl.At 100 mM NaCl, glutamine synthetase (GS) and NADH-glutamate dehydrogenase (GDH) activitieswere similar to controls, whereas a significant increase (64%) in NADH-glutamate synthase (GOGAT)activity was observed. GS activity did not change at 200 mM salt treatment, but GOGAT and GDHsignificantly decreased (40 and 50%, respectively). When gene and protein expression of GS andGOGAT were analysed, it was found that they were positively correlated with enzyme activities. Inaddition, heme oxygenase (HO) activity, protein synthesis and gene expression were significantlyincreased under 100 mM salt treatment. Our data demonstrated that the up-regulation of HO, as part ofantioxidant defence system, could be protecting the soybean nodule nitrogen fixation and assimilationunder saline stress conditions.