The effect of nitrite on glutamine synthetase level in isolatedPisutn sativutn L. roots

Abstract

Exposure of isolated pea roots to 0.5 and 2.0 mM nitrite resulted in a temporary decrease in glutamine synthetase (GS) level. The GS level decrease was preceded by a temporary increase in NO2- content: nitrite content maximum was observed after 6 h exposure, GS level was depressed most after 12 h. At this time, GS level also significantly decreased by 0.3 and 0.4 mM NO2-, but the effect of these concentrations was only slight and not significant after 18 h exposure. By contrast, GS level in roots precultivated for 24 h in solutions containing 2 mM NO2- did not fully recover even after further 24 h cultivation in nutrient solutions lacking NO2-. The inhibitory effect of NO2-on GS level was stressed by lack of sugar in nutrient solutions. Nitrite did not affect GS activity (transferase reaction)in vitro. The decrease in GS level due to exposure to No2- was accompanied by KH3 excretion to nutrient solution.