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.

Regulation Of Growth And Cellular Differentiation In Developing Avena Internodes By Gibberellic Acid And Indole‐3‐Acetic Acid

Abstract: Auxini (IAA) at physiological concentrations causes significant reduction of GA3-promoted growth in excised Avmna stem segments. IAA is thus considered to be a gibberellin antagonist in this system. It was found to act non-competitively in repressing GA3-augmented growth in these segments. In intercalary meristem cells at the base of the elongating internode, GA3 blocks cell division activity and causes a marked increase in cell lengthening. IAA substantially promotes lateral expansion in comparable intercalary meristem cells, particularly in the vicinity of vascular bundles underlying the epidermis. It also alters the plane of cell division in differentiating stomata. IAA at high concentrations (10-3, 10-4 M), in combination with GA3, overrides the effects of GA3 on cell lengthening, while with low concentrations of IAA (10-9, lO-10 M), the effects of GA,3 are clearly dominant. At intermediate concentrations of IAA (10-6, 10-7 M), in the presence of GA.3, the effects of this treatment on cell differentiation closely parallel the pattern of differentiation in untreated tissue. It is postulated that a lateral gradient of auxin and gibberellin could control cell expansion in long epidermal cells during intercalary growth

Effect of Exogenous General Plant Growth Regulators on the Growth of the Duckweed Lemna minor.

Abstract: Gibberellic acid (GA3), indole-3-acetic acid (IAA), salicylic acid (SA), abscidic acid (ABA), jasmonic acid (JA) 1-amino cyclopropane-1-carboxylic acid (ACC) and aminoethoxyvinylglycine (AVG) are popular growth regulators of plants. However, the effects of their exogenous addition on the biomass production of aquatic plants, including Lemnoideae plants, "duckweeds," are largely unknown. In this study, the growth of Lemna minor was tested for 10 d in Hoagland medium containing each compound at different concentrations of 0-50 μM. GA3, IAA, and SA were found to have no apparent positive effect on the growth at all concentrations tested. Conversely, ACC and JA moderately and AVG and ABA severely inhibited the growth of L. minor. Among the tested compounds, ascorbic acid had an apparent growth-promoting effect.

Triadimefon: Mode of action in plants and fungi

Abstract: Triadimefon retarded the elongation of the upper internodes of shoots of tomato and cotton plants. The growth retardation was completely reversed by exogenously applied gibberellic acid (GA3). Growth of coleoptiles, primary leaves and roots of wheat and barley seedlings was reduced after seed treatment with triadimefon; application of GA3 did not completely counteract this growth retardation. Leaves of triadimefon-treated plants showed a darker green colour; leaves became lighter again when the growth retardation was reversed by GA3 application. When detached leaf sections were floated in triadimefon solutions or suspensions in the dark, senescence was delayed. The compound showed only a weak antagonistic effect on GA3-induced α-amylase synthesis in barley endosperm. Triadimefon strongly reduced the synthesis of gibberellin-like substances in Fusarium moniliforme. It inhibited the development of haustoria of Erysiphe graminis f. sp. hordei. Studies on its mode of action revealed that triadimefon blocked ergosterol biosynthesis in Ustilago avenae.

The physiological basis of seed dormancy in Avena fatua L. I. Action of the respiratory inhibitors sodium azide and salicylhydroxamic acid

Abstract: The dormancy breaking effect of sodium azide was studied in seeds of several genetically pure lines of Avena fatua L. isolated from field populations. Sodium azide (0.8 and 1 mM) induced germination in several dormant lines (characterized by long term dormancy) after two weeks of treatment. By about five weeks, germination was nearly complete in azide treated seeds as compared to little or no germination in controls. (2-chloroethyl) trimethylammonium chloride (an inhibitor of gibberellin biosynthesis) completely inhibited the azide effect suggesting that stimulation of germination by azide requires gibberellin biosynthesis. Azide was very effective in breaking dormancy in lines AN-51, AN-86, AN-127 and AN-265, but failed to induce germination in Montana 73. In this line there was a synergism between azide and gibberellic acid in promotion of germination. Thus, at least two metabolic blocks are involved in the stimulation of germination in this line. Salicylhydroxamic acid (an inhibitor of alternative respiration) at 3 mM completely inhibited the germination induced by 1 mM azide. At this concentration, salicylhydroxamic acid did not inhibit germination in 1) genetically nondormant seeds (line SH-430), 2) afterripened seeds of a dormant line (AN-51), and 3) gibberellic acid-treated dormant seeds. These findings suggest that salicylhydroxamic acid-sensitive process(es), presumably alternative respiration, is necessary for the stimulation of germination in the presence of azide, but not in the germination of genetically nondormant, gibberellic acid-treated dormant, or afterripened seeds.

Influence of Growth Regulators on Root and Shoot Initiation from Flax Meristem‐Tips and Hypocotyls in vitro

Abstract: Hypocotyl sections and isolated meristem-tips from 7- to 10-day-old seedlings of flax were cultured on a Murashige and Skoog (1962) medium. The optimum concentrations of naphthaleneacetic acid (NAA) and benzyladenine (BA) were determined for shoot and root initiation from hypocotyls. Meristem-tip cultures differentiated shoots and roots in response to these concentrations. The frequency and yield of shoots, promoted by BA, decreased if NAA or gibberellic acid (GA3) was included in the medium. At high NAA concentration GA3 and BA inhibited root initiation. Morphological development of cultures differed depending on the growth regulators in the medium.