Showing papers on "Gibberellic acid published in 1984"

Role of gibberellin in the growth response of submerged deep water rice.

Abstract: We have shown previously that ethylene, which accumulates in the air spaces of submerged stem sections of rice (Oryza sativa L. cv "Habiganj Aman II"), is involved in regulating the growth response caused by submergence. The role of gibberellins in the submergence response was studied using tetcyclacis (TCY), a new plant growth retardant, which inhibits gibberellin biosynthesis. Stem sections excised from plants that had been watered with a solution of 1 micromolar TCY for 7 to 10 days did not elongate when submerged in the same solution or when exposed to 1 microliter per liter ethylene in air. Gibberellic acid (GA(3)) at 0.3 micromolar overcame the effect of TCY and restored the rapid internodal elongation in submerged and ethylene-treated sections to the levels observed in control sections that had not been treated with TCY. The effect of 0.01 to 0.2 micromolar GA(3) on internodal elongation was enhanced two- to eight-fold when 1 microliter per liter ethylene was added to the air passing through the chamber in which the sections were incubated. GA(3) and ethylene caused a similar increase in cell division and cell elongation in rice internodes. Thus, ethylene may cause internodal elongation in rice by increasing the activity of endogenous GAs. In internodes from which the leaf sheath had been peeled off, growth in response to submergence, ethylene and GA(3) was severely inhibited by light.

The effects of gibberellic acid and abscisic acid on α-amylase mRNA levels in barley aleurone layers studies using an α-amylase cDNA clone.

Abstract: Two cDNA clones were characterized which correspond to different RNA species whose level is increased by gibberellic acid (GA3) in barley (Hordeum vulgare L) aleurone layers On the criteria of amino terminal sequencing, amino acid composition and DNA sequencing it is likely that one of these clones (pHV19) corresponds to the mRNA for α-amylase (1,4-α-D-glucan glucanohydrolase, EC 3211), in particular for the B family of α-amylase isozymes (Jacobsen JV, Higgins TJV: Plant Physiol 70:1647–1653, 1982) Sequence analysis of PHV19 revealed a probable 23 amino acid signal peptide Southern hybridization of this clone to barley DNA digested with restriction endonucleases indicated approximately eight gene-equivalents per haploid genome The identity of the other clone (pHV14) is unknown, but from hybridization studies and sequence analysis it is apparently unrelated to the α-amylase clone Both clones hybridize to RNAs that are similar in size (∼1500b), but which accumulate to different extents following GA3 treatment: α-amylase mRNA increases approximately 50-fold in abundance over control levels, whereas the RNA hybridizing to pHV14 increases approximately 10-fold In the presence of abscisic acid (ABA) the response to GA3 is largely, but not entirely, abolished These results suggest that GA3 and ABA regulate synthesis of α-amylase in barley aleurone layers primarily through the accumulation of α-amylase mRNA

Effect of plant hormones on sucrose uptake by sugar beet root tissue discs.

Abstract: Abscisic acid (ABA), auxins, cytokinins, gibberellic acid, alone or in combination were tested for their effects on short-term sucrose uptake in sugar beet (Beta vulgaris cv USH-20) roots. The effect of ABA on active sucrose uptake varied from no effect to the more generally observed 1.4-to 3.0-fold stimulation. A racemic mixture of ABA and its trans isomer were more stimulatory than ABA alone. Pretreating and/or simultaneously treating the tissue with K+ or IAA prevented the ABA response while cytokinins and gibberellic acid did not. While the variable sensitivities of beet root to ABA may somehow be related to the auxin and alkali cation status of the tissue, tissue sensitivity to ABA was not correlated with ABA uptake, accumulation, or metabolic patterns. In contrast to ABA, indoleacetic acid (IAA) and other auxins strongly inhibited active sucrose uptake in beet roots. Cytokinins enhanced the auxin-induced inhibition of sucrose uptake but ABA and gibberellic acid did not modify or counteract the auxin effect. Trans-zeatin, benzyladenine, kinetin, and gibberellins had no effect on active sucrose uptake. None of the hormones or hormone mixtures tested had any significant effect on passive sucrose uptake. The effects of IAA and ABA on sucrose uptake were detectable within 1 h suggesting a rather close relationship between the physiological activities of IAA and ABA and the operation of the active transport system.

Initiation and morphological development of somatic embryoids from barley cell cultures

Abstract: Somatic embryogenesis was induced in callus previously initiated from immature embryos of barley. These cultures ranged in age from 6 weeks to 30 months. Embryoids were readily initiated from homogenized suspension-grown aggregates when plated on modified B5 media with 2,4-dichlorophenoxyacetic acid. Low concentrations (0.1 and 0.05 mg∙L−1) of abscisic acid promoted further maturation of embryoids, while gibberellic acid (1 mg∙L−1) and kinetin (0.1 mg∙L−1) were used in the media to encourage embryoid germination. The development of somatic embryoids from initiation through maturation and germination is described.

Inhibition of flavonoid biosynthesis by gibberellic acid in cell suspension cultures of Daucus carota L

Abstract: In carrot cells (Daucus carota L.), cultured in the presence of gibberellic acid, anthocyanin synthesis is blocked at the level of chalcone synthase. By feeding suitable precursors for anthocyanins (naringenin, eriodictyol, dihydroquercetin) biosynthesis of cyanidin glycosides can be restored. After addition of these substrates to the culture medium in the presence of gibberellic acid, the activity of chalcone synthase remained as low as in the control without precursors. The highest increase in anthocyanin content was achieved using dihydroquercetin as the added precursor. The time course of this supplementation showed a rapid response; within 4 h a substantial increase in anthocyanin could be observed. In contranst, the flavonol quercetin is not a precursor for cyanidin. The fact that naringenin was also accepted for cyanidin synthesis leads to the conclusion that hydroxylation in 3′-position of ring B in Daucus carota takes place at the flavonoid stage.

Controlled regeneration of cotton plants from tissue culture

Abstract: The regeneration of plants from cotton callus (Gossypium hirsutum L. cv Coker 310) is described. Somatic proembryoids developed spontaneously after two years in culture on a modified Linsmaier and Skoog medium. The percentage of calli forming proembryoids was increased to about 30% by prolonged culture without NAA and kinetin. Development of proembryoids was enhanced by transferring proembryoids to media lacking NH 4 NO 3 but containing double the standard KNO 3 concentration and gibberellic acid. Root initiation and growth was promoted by lowering the glucose concentration to 5 g/l.

Biochemical and physiological aspects of leaf development in cocoa (theobroma cacao)

Abstract: Summary The dormant phase of the flush cycle of leaf growth in cocoa is known to be correlated with high abscisic acid (ABA) levels in the mature leaves of the new flush (NF) and previous flush (PF) leaves. Defoliation of either the NF leaves or PF leaves of cocoa seedlings reduced the length of the dormant phase of the flush cycle, thus showing that the mature leaves were a source of growth inhibitors which could affect shoot apical activity. The application of ABA to the NF and PF leaves led to an extension of the dormant phase, whereas application of zeatin or gibberellic acid decreased it. The distribution of [14C]ABA following its application to NF and PF leaves at different stages throughout the growth cycle showed that [14C] ABA was accumulated by the bud in relatively larger amounts during the final stages of bud dormancy (I-1 and I-2) than in the earlier stage (F-2). The results suggest that internal competition for nutrients may be responsible for the inhibition of growth at the F-2 stage but that ABA translocated from the mature leaves causes the buds to remain dormant during the subsequent stages of I-1 and I-2.

Effects of gibberellic Acid on endogenous indole-3-acetic Acid and indoleacetyl aspartic Acid levels in a dwarf pea.

Abstract: Two-week-old dwarf peas (Pisum sativum cv Little Marvel) were sprayed with gibberellic acid (GA3), and after 3 or 4 days the upper stem and young leaf samples were analyzed for indole-3-acetic acid (IAA) and indole-3-acetyl aspartic acid by an isotope dilution high performance liquid chromatography method. GA3 increased IAA levels as much as 8-fold and decreased indole-3-acetyl aspartic acid levels.

Promotion and inhibition by plant growth regulators of aerenchyma formation in seedling roots of Zea mays

Abstract: The influence of naphthylacetic acid, abscisic acid, gibberellic acid and kinetin on the formation of aerenchyma in seedling roots of Zea mays L. cv. Capella has been studied in relation to reported changes of their concentration in poorly aerated roots, which readily form aerenchyma, and to the effects of these hormones on the production of ethylene, a major factor promoting aerenchyma formation. Because the absence of nitrate accelerates aerenchyma formation in aerated roots, their influence on these roots was compared. The growth regulators were added to roots growing in non-aerated and aerated nutrient solutions, and aerenchyma formation and the production and endogenous concentration of ethylene were measured. Naphthylacetic acid prevented aerenchyma formation in both aerated roots without nitrate and in non-aerated roots although it enhanced the ethylene concentration of the roots. Abscisic acid also prevented aerenchyma formation, but without affecting the ethylene concentration. Gibberellic acid promoted aerenchyma formation in aerated roots only, but ethylene production in both aerated and non-aerated roots. Kinetin promoted aerenchyma formation in both aerated and non-aerated roots. It stimulated ethylene production in aerated roots, but slightly inhibited it in non-aerated roots. Co2+ and Ag+, which suppress ethylene production and action, respectively, reduced the promoting effects of gibberellic acid, but not those of kinetin. It is concluded that the effects of the plant growth regulators on aerenchyma formation in maize roots were, with a possible exception for gibberellic acid, not the result of altered ethylene concentrations in the roots. Their influence on aerenchyma formation is discussed in relation to their reported actions on cell membranes.

Tomato growth as affected by root-zone temperature and the addition of gibberellic acid and kinetin to nutrient solutions

Abstract: The effect of root-zone temperature on young tomato plants (Lycopersicon esculentum Mill. cv. Heinz 1350) was evaluated in controlled environments using a recirculating solution culture system. Growth rates were measured at root-zone temperatures of 15 degrees, 20 degrees, 25 degrees, and 30 degrees C in a near optimum foliar environment. Optimum growth occurred at 25 degrees to 30 degrees during the first 4 weeks of growth and 20 degrees to 25 degrees during the 5th and 6th weeks. Growth was severely restricted at 15 degrees. Four concentrations of gibberellic acid (GA3) and kinetin were added to the nutrient solution in a separate trial; root-zone temperature was maintained at 15 degrees and 25 degrees. Addition of 15 micromoles GA3 to solutions increased specific leaf area, total leaf area, and dry weight production of plants in both temperature treatments. GA3-induced growth stimulation was greater at 15 degrees than at 25 degrees. GA3 may promote growth by increasing leaf area, enhancing photosynthesis per unit leaf area, or both. Kinetic was not useful in promoting growth at either temperature.

Low Temperature Induction of Hormonal Sensitivity in Genotypically Gibberellic Acid-Insensitive Aleurone Tissue

Abstract: An exposure of genetically gibberellic acid-insensitive isolated wheat aleurone tissue/deembryonated seeds to low temperature for 20 hours prior to addition of exogenous gibberellic acid results in a significant increase in sensitivity to gibberellic acid. The results may reflect a low temperature-induced increase in hormone receptor sites and could have important implications for elucidating the nature of the primary site of hormone action.

Dormancy responses to post-harvest application of growth regulators in Dioscorea species. I: Responses of bulbils, tubers and tuber pieces of three Dioscorea species

Abstract: The effects on dormancy of post-harvest application of growth regulators to bulbils, tubers and tuber pieces of tropical Dioscorea species were examined. Abscisic acid, kinetin, indole acetic acid and 2-chloroethyltrimethylammonium chloride were found to have little or no effect on either shoot or tuber-root production, while ethrel greatly promoted tuber-root production with little or no effect on shoot development. The germination of slices of tubers of D. alata was delayed by maleic hydrazide but there was no effect on intact tubers of D. alata and D. esculenta. Treatment with 2,4-dichlorophenoxyacetic acid caused massive root and callus development along with delay in shoot development, while gibberellic acid occasioned marked extensions in the dormant period.

Germination of Clematis microphylla seeds following weathering and other treatments

Abstract: Germination of Clematis microphyiia seeds was quicker following pericarp removal or if exposed previously to a cycle of wetting and drying. Germination was also quicker following field weathering of seeds; this effect is attributed to pericarp decay and to embryo development during intermittent wet periods. Addition of gibberellic acid or nitrate advanced germination only slightly. Treatments which resulted in the most rapid germination of the first seeds did not necessarily advance germination of whole populations. We interpret the ability of C. microphylla seeds to withstand desiccation at advanced stages of germination without reverting to their state before imbibition as an adaptive feature which both provides a timing mechanism for germination and may also hasten seedling establishment.

Induced parthenocarpy-a way of manipulating levels of endogenous hormones in tomato fruits (Lycopersicon esculentum Mill.) 2. Diffusible hormones

Abstract: Indol-3-acetic acid (IAA), gibberellin-like substances (GAs), and abscisic acid (ABA) were measured throughout the first 35 days of fruit development in agar diffusates from seeded and parthenocarpic tomato fruits. Parthenocarpic fruit growth was induced with either an auxin (4-CPA), morphactin (CME) or gibberellic acid (GA3). IAA and GAs were at their highest levels in diffusates during the early stages of fruit growth, whereas diffusible ABA increased later. Most IAA was found in diffusates from auxin-induced and seeded fruits, whereas GAs were at their lowest levels in seeded fruits. There were only minor differences in ABA concentrations regardlesss of the treatments.

Gibberellic Acid Controls the Secretion of Acid Phosphatase in Aleurone Layers and Isolated Aleurone Protoplasts of Avena fatua

Abstract: The role of gibberellic acid (GA,) in controlling the secretion (across the plasma membrane) and release (through the cell wall) of acid phosphatase (E.C. 3.1.3.2.) from Avena aleurone layers has been investigated. Evidence from this comparative study with intact aleurone layers and isolated aleurone protoplasts reveals that the secretion of acid phosphatase is under GA, control. The mechanism underlying secretion and release of the enzyme from aleurone cells is discussed.

Interaction of gibberellic acid, abscisic acid, and phenolic compounds in the control of hypocotyl growth of Amaranthus caudatus seedlings

Abstract: Abscisic acid, a potent growth inhibitor, inhibits hypocotyl growth of Amaranthus caudatus (L.) seedlings. Phenolic compounds when applied with ABA (abscisic acid), antagonize ABA action and restor...

Changes in levels of transcripts in endosperms of castor beans treated with exogenous gibberellic acid.

Abstract: A complementary-DNA library to mRNA from castor-bean endosperm has been prepared. Three clones have been examined in detail. One of these is complementary to isocitrate-lyase mRNA. The other two clones code for proteins with M r , 42000 and 38000. All three clones have been used to measure levels of transcripts during seed germination. The three transcripts all increased during germination and the rate of their appearance is stimulated by exogenous GA3. The data strongly support the view that the action of GA3 in these seeds is to stimulate non-specifically the rate of transcription and, in turn, protein synthesis. Possible mechanisms for the action of the growth regulator are discussed.

Preliminary investigation of the effects of gibberellic acid (GA3) on sucker development in plantain (Musa cv. AAB) under field conditions

Abstract: The delay of sword sucker development until after floral initiation and the apparent cessation of apical dominance in plantains is believed to be the major cause of poor ratoon development and, consequently, rapid yield decline in succeeding ratoons. Gibberellic acid (GA3) at concentrations of 10-2M, injected into peepers at two-day intervals for two, four and six weeks, stimulated sword sucker development before floral initiation after two weeks of treatment. Since treatment duration had no significant effect, it is suggested that sword sucker development is the response to GA flushes and that GA flushes affect only peepers that are physiologically sensitive to GA at the time of flush. Therefore, it is possible for dormant peepers and active sword suckers to be present on the same mother plant. The injected GA3 had no abnormal effect on the treated sucker or the mother plant.

Endosperm dormancy breakage in olive seeds

Abstract: Seeds of Olea europaea L. ssp. oleaster Hoffm. and Link freed from the sclerous endoearp and incubated in water at 15 or 25°C in darkness or in 12:12 h white light:dark conditions, did not germinate, due to dormancy imposed by the endosperm. Seeds also did not germinate when incubated in abscisic acid, gibberellic acid, kinetin or zeatin in darkness and at cither 15 or 25°C. SAN 9789 |4-chloro-5-(methylamine)-2-(a,a,a-trifluoro-m-tolyl)-3-(2H)-pyridazmone] did not promote germination at 15°C but it did to a 75% level at 25°C. This promoting effect of SAN was counteracted by abscisic acid. Cultures of naked embryos grew equally well in the presence or absence of SAN 9789. 6-Benzylaminopurine promoted whole seed germination to a 15% level.