Gibberellic acid

About: Gibberellic acid is a research topic. Over the lifetime, 6597 publications have been published within this topic receiving 109294 citations. The topic is also known as: GIBBERELLIN A3.

Determination of endogenous hormones, sugars and mineral nutrition levels during the induction, initiation and differentiation stage and their effects on flower formation in olive

Abstract: Olive (Olea europaea L.) is one of the most important crop plants grown in the Mediterranean region. Varying levels of hormones, sugars and mineral nutrient are thought to influence flower bud formation. The objective of this study was to evaluate the changes in endogenous sugar, mineral nutrition and hormone levels in leaf, node and fruit samples of ‘Memecik’ olive during the induction, initiation and differentiation periods in on (bearing) and off (non-bearing) years. Leaf, node and fruit samples of mature 15-year-old Memecik olive were used. The samples were taken during the induction, initiation and differentiation periods of olive in on (2000) and off (2001) years. Sugar (glucose, fructose and sucrose), mineral nutrient (N, P, K, Ca, Mg, Fe, Zn, Mn and Cu) and hormone [abscisic acid (ABA), indole acetic acid (IAA), gibberellic acid (GA3, GA4) and zeatin (Z)] levels were determined in on and off years. Hormone and sugar levels were measured by gas chromatography and high-performance liquid chromatography. The K, Ca, Mg, Fe, Mn, Zn and Cu levels were quantified by an atomic absorption spectrophotometry. Nitrogen was determined by the Kjeldahl procedure, and P by a spectrophotometric method. The differences in any of the sugar concentrations, with the exception of fructose, were not significant in on and off years. Hormone levels, however, were significantly different in on and off years. Glucose had the highest concentrations in both years, followed by sucrose and fructose, respectively. The highest macro and micro element concentrations were found to be Ca and Fe, respectively. Thus, the results suggest that carbohydrates and mineral nutrients may not have a direct effect to induce flower initiation. However, high GA3 level exhibited an inhibitory effect on floral formation during the induction and initiation periods. On the other hand, the high concentrations of GA4, ABA and certain cytokinin levels may have a positive effect on flower formation in olive during the induction and initiation periods.

Geranyl diphosphate synthase is required for biosynthesis of gibberellins

Abstract: Geranyl diphosphate synthase (GPS) is generally considered to be responsible for the biosynthesis of monoterpene precursors only. However, reduction of LeGPS expression in tomato (Lycopersicon esculentum) by virus-induced gene silencing resulted in severely dwarfed plants. Further analysis of these dwarfed plants revealed a decreased gibberellin content, whereas carotenoid and chlorophyll levels were unaltered. Accordingly, the phenotype could be rescued by application of gibberellic acid. The dwarfed phenotype was also obtained in Arabidopsis thaliana plants transformed with RNAi constructs of AtGPS. These results link geranyl diphosphate (GPP) to the gibberellin biosynthesis pathway. They also demand a re-evaluation of the role of GPS in precursor synthesis for other di-, tri-, tetra- and/or polyterpenes and their derivatives.

Production of gibberellic acid by fermentation.

Abstract: The elonigationi of rice plants iinduced by the application of cell-free culture filtrates from the li(uid culture of Futsariutm moniliforme was first demonstrated in 1926 by Kurosawa. Twelve years later, Yabuta and Sumiki (1938) were able to isolate in crystalline form two growth-promotinig compounds, gibberellins A and B, from filtrates of this organism; gibberellin A was the maini substaniee obtained. In 1954, Curtis and Cross reported the discovery of a third metabolite, gibberellic acid, from a culture filtrate of Gibberella fuijikuroi, the perfect stage of F. moniliforme. This finding was con1firmed the followinig year by Stodola et al. (1955) and Takahashi et al. (1955). Brian anid Grove (1957) have writteni anl excellent comprehensive review of the gibberellins with emphasis placed upon gibberellic acid. It is this compounid with which we are concerned at this time. A complete literature review has been prepared by Stodola (1958). The straini of Fuisariuim m9niliformestraini Kewno.917, which we used for these investigational studies, was the one reported by Borrow et al. (1955) to give the highest yield of gibberellic acid. With this culture and a medium composed of glucose, 40 g per L; ammonium tartrate, 9.5 g per L; moniopotassium phosphate, 2.0 g per L; potassium sulfate, 0.6 g per L; and magnesium sulfate, 0.2 g per L; they obtained 180 mg per L gibberellic acid. The yields obtained by Borrow et al. in a medium used by Yabuta, Sumiki, and Uno (1939) consisting of glycerol or glucose, ammonium chloride, and monopotassium phosphate were negligible with all of the Kew cultures. The former value of 180 mg per L gibberellic acid is substantially greater than that of 22 mg per L reported by Stodola et al. (1955) in a medium consisting of glucose, 15 g per L; monopotassium phosphate, 3 g per L; ammoniium chloride, 3 g per L; land magniesium sulfate, 3 g per L. Usinig the Kewv no. 917 culture we obtained gibberellic acid yields of 880 mg per L in shaker flasks anid 650 mg per L in 1000-gallon fermentors.

Gibberellin and cytokinin effects on soybean growth

Abstract: Soybean is an important crop in Brazil. Nonetheless, there are no reports on the use of plant growth regulator potential in relation to this crop in the national literature. To better understand the role of these compounds, a pot experiment was carried out to study effects of GA3 and cytokinin on the vegetative growth of the soybean. GA3 (50 mg L-1) was applied as seed treatment, leaving plants with water application as control. GA3 (100 mg L-1) and cytokinin (30 mg L-1) were sprayed on leaves at the physiological stage V3/V4, and 15 days after, cytokinin (30 mg L-1), also as foliar spray. Seed treatment decreased plant emergence and initial soybean root growth, but as the season progressed, differences in root growth disappeared; plants were shorter, and presented a decrease in the number of nodes, in stem diameter, in leaf area and in dry matter yield. Conversely, foliar application of GA3 led to an increase in plant height, first node height and stem diameter. Leaf area and dry matter production also increased as a result of GA3 foliar application. There was no effect of exogenous gibberellin and cytokinin on the number of soybean leaves, number of stem branches and root dry matter. Joint application of gibberellin and cytokinin tended to inhibit gibberellin effects. Cytokinin applied to leaves during soybean vegetative growth was not effective in modifying any of the evaluated plant growth variables.