Negative regulation of asparagine synthetase in the leaves of maize seedlings by light, benzyladenine and glucose

Abstract

Asparagine synthetase (EC 6.3.5.4) activity was increased 4‐ and 8‐fold when maize (Zea mays L.) seedlings were kept in darkness for 24 h and 7 days, respectively; this increase was abolished by cycloheximide. Irradiation of the dark adapted seedlings with a pulse of red light resulted in a 4‐fold decrease of the enzyme activity within 48 h, which was raised again following a far‐red light pulse. Co‐action of light and benzyladenine, reported for the light‐inducible enzymes, was proved to hold also for the light‐repressible asparagine synthetase. The induction of asparagine synthetase activity in the dark is abolished by glucose, suggesting the possible involvement of the enzyme in the contrae of metabolic fluxes of –carbon and nitrogen through assimilatory pathways.