Efeito do ácido giberélico e diferentes aminoácidos sobre as atividades da sintetase da glutamina e sintase do glutamato e sobre o crescimento de frutos de soja

摘要

The work had as objective to evaluate the effect of different aminoacids and of the gibberelic acid (GA) on the activity of glutamine synthetase (GS) and glutamate synthase (GOGAT) and the growth of soybean fruits. Immature fruits were cultivated with different paclobutrazol (PBZ) concentrations, inhibitor gibberellin synthesis, which it inhibited the growth of the fruits in up to 80%. In a second stage, the effect of the GA was evaluated on the growth of the soybean fruits cultivated with PBZ. The growth regulator reestablished the growth of the cultivated fruits with 0,034 mM PBZ. However, with 0,85 mM PBZ it was not obtained the same positive effect, indicating a possible level phytotoxic. Following fruits was cultivated during eight days, with glutamine, asparagine or allantoine, with or without GA, after which the enzymatic activities were determined. The enzymes of assimilation of the nitrogen went more active under presence of the allantoine. The GA inhibited the GS activity and it stimulated the of Fd-GOGAT and of NADH-GOGAT. The Fd-GOGAT activity went superior of the NADH-GOGAT, perhaps due to reduced ferredoxin in the cultivated fruits under constant illumination, advent of the photosynthetic. The results indicate that, probably, gibberellins are involved in the growth of immature fruits of soybean and in regulation enzymatic activities of the GS and GOGAT in that fruits.