EFFECT OF SALINITY ON METALLOENZYMES OF OXYGEN-METABOLISM IN 2 LEGUMINOUS PLANTS

Superoxide dismutase (SOD) pattern, catalase, Cyt c oxidase and fumara se activity were studied in leaves of Phaseolus vulgaris and Vigna ung uiculata plants growth in two sodium chloride (NaCl) concentrations (3 5 mM and 100 mM). In bean plants growth with NaCl, leaf chloride (Cl-) contents were higher than in control plants, and the same was found f or sodium (Na+) and potassium (K+) contents, although to a lesser degr ee. In cowpea leaves, Na+ and Cl- had a similar increase due to salt-g rowth conditions. Under salinity, all changes in the antioxidant (SOD and catalase) enzymes levels were smaller in bean than in cowpea plant s. In Phaseolus at 15 days growth, Cu, Zn-SOD I showed an increase by the effect of salt treatment, but this induction did not occur at 30 d ays growth, and both Mn-SOD and Cu, Zn-SOD II did not show variations due to salt-stress. In Vigna, Mn-SOD was decreased by salinity but thi s was compensated by an increase in Cu, Zn-SOD I activity in plants at 30 days growth, whereas in young leaves under saline conditions, both isozymes were also decreased. Likewise, there was a rise in cytochrom e c oxidase and fumarase activity in leaves of NaCl-treated plants com pared to the control. The activity changes observed are discused in te rm of their possible relevance to plant sensitivity to saline conditio ns.