Effect of exogenous polyamines on glycolate oxidase activity and active oxygen species accumulation in wheat seedlings under osmotic stress

Abstract

Exogenous polyamines applied to wheat roots increased both polyamine content and glycolate oxidase activity in leaves. -0.85 MPa osmotic stress not only increased the content of O-2(-) and H2O2, but also decreased glycolate oxidase activity in leaves, and 5 mM putrescine, 2 mM spermidine, and 1 mM spermine partly inhibited these effects. Exogenous oxalic acid decreased glycolate oxidase activity, increased O-2(-) content, and had no effect on H2O2 content. The correlation coefficient between glycolate oxidase activity and O-2(-) content was -0.89. These results suggest that exogenous polyamines inhibit O-2(-) accumulation under osmotic stress by enhancing glycolate oxidase activity. Exogenous polyamines also inhibit H2O2 accumulation in wheat seedlings under osmotic stress, but this does not correlate With the glycolate oxidase activity.