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

Abstract

-(Effect of the gibberellic acid and different aminoacids on the activities of glutamine synthetase and glutamate synthase, and on growth of soybean fruits). 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.Key words -aminoacids, gibberellin, growth regulator, nitrogen, paclobutrazol RESUMO -(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). O trabalho teve como objetivo avaliar o efeito de diferentes aminoácidos e do ácido giberélico (GA) sobre a atividade da glutamina sintetase (GS) e da glutamato sintase (GOGAT) e o crescimento de frutos de soja. Frutos imaturos foram cultivados com diferentes concentrações de paclobutrazol (PBZ), inibidor da biossíntese de giberelinas, o qual inibiu o crescimento dos frutos em até 80%. Em seguida foi avaliado o efeito do GA sobre o crescimento dos frutos de soja cultivados com PBZ. O regulador de crescimento restabeleceu o crescimento dos frutos cultivados com 0,034 mM de PBZ. Entretanto, com 0,85 mM de PBZ não se obteve o mesmo efeito positivo, indicando um possível nível fitotóxico. Posteriormente os frutos foram cultivados durante oito dias com glutamina, asparagina ou alantoína, na presença ou não de GA, após o que determinaram-se as atividades enzimáticas. As enzimas de assimilação do nitrogênio foram mais ativas na presença da alantoína. O GA inibiu a atividade da GS e estimulou as da Fd-GOGAT e da NADH-GOGAT. A atividade da Fd-GOGAT foi superior à da NADH-GOGAT, talvez devido à ferredoxina reduzida presente nos frutos cultivados sob iluminação constante, advinda da atividade fotossintética. Os resultados obtidos permite...

Attributes of growth, physiological quality and isoenzymatic expression of common bean seeds produced under the effect of gibberellic acid

“…Among the groups of growth regulators, gibberellin has a marked effect on the seed germination process, activating hydrolytic enzymes, such as α-amylase and protease, that actively act in the unfolding of the reserve substances, facilitating the mobilization of the endosperm (George et al, 2008). In addition, it plays an important role in the development and physiological actions of plant tissues, gibberellic acid acts directly on tissue differentiation (Duan;Mosquim, 2004;Amarante et al, 2005;DoNascimento;Ju;Khan et al 2006). Giberelins are responsible for several important physiological functions in the development of superior plants (Hooley 1994, Lange 1998.…”