Effect of salicylic acid on nadh glutamate synthase activity in root and leaf tissues of maize seedlings

NADH glutamate synthase activity was stimulated by 1 to 1000 μM salicylic acid (SA) in the leaf and by 50 to 100 μM SA in the root tissues of maize seedlings. Higher concetrations of SA inhibited enzyme activity in both tissues. The stimulatory concentrations of SA protected both in vivo and in vitro decline in enzyme activity to some extent, which was more apparent in leaves than in roots. When supplied with SA, cycloheximide inhibited the enzyme activity in either of the tissues, where as chloramphenicol could do so to some extent only in root tissues. It is suggested that salicylic acid increases glutamate synthase activity by inducing synthesis of enzyme as well as by some kind of direct modulation of the enzyme molecule.