Showing papers on "Gibberellic acid published in 1981"
TL;DR: Histological examination of proliferating leaves of Panicum maximum Jacq showed that the embryogenic callus tissue was formed by divisions in cells of the lower epidermis as well as the mesophyll tissue.
Abstract: Somatic embryogenesis was induced in proliferating leaf segments of Panicum maximum Jacq., cultured on Murashige and Skoog's nutrient medium containing 2,4-dichlorophenoxyacetic acid and coconut milk. The embryoids gave rise to plants on a medium containing gibberellic acid. The plants were successfully transplanted to soil and grown to maturity. Histological examination of proliferating leaves showed that the embryogenic callus tissue was formed by divisions in cells of the lower epidermis as well as the mesophyll tissue. The regenerated plants showed the normal chromosome number of 2n=4x=32.
130 citations
TL;DR: Some of the important events necessary for adventitious root production occur during the first few hours after excision of the original root system, and it is suggested that the hypocotyl cells on the first day go through aphase during which primordia production is blocked by endogenous ethylene and on the second day enter a phase during which endogenous Ethylene promotes rooting.
Abstract: The effect of brief application (usually for 3 h) of various growth regulators and their antagonists on the production of adventitious root primordia in sunflower hypocotyls over a 3 day period, was investigated. Gibberellic acid inhibited, while an inhibitor of gibberellin biosynthesis promoted rooting. Low concentrations of cytokinins increased, but higher levels inhibited primordia formation. Auxin was able to stimulate or inhibit root production, depending upon the quantity applied, and triiodobenzoic acid applied to the top of the hypocotyls lowered the rate of root formation.
From experiments in which benzyladenine, silver nitrate and benzyl isothiocyanate were supplied to the hypocotyl for various 3 h periods after root removal, we concluded that some of the important events necessary for adventitious root production occur during the first few hours after excision of the original root system. We also suggest that the hypocotyl cells on the first day go through a phase during which primordia production is blocked by endogenous ethylene and on the second day enter a phase during which endogenous ethylene promotes rooting.
83 citations
TL;DR: A highly sensitive and specific radioimmunoassay which allows the detection of as little as 5 fmol (2 pg) of gibberellic acid (GA3) in crude plant extracts is described, and only the closely related GA7 is highly immunoreactive.
Abstract: A highly sensitive and specific radioimmunoassay which allows the detection of as little as 5 fmol (2 pg) of gibberellic acid (GA3) in crude plant extracts is described. Antisera of high affinity and titer were obtained by immunizing rabbits with a conjugate of carboxyl-coupled GA3 and bovine serum albumin. [125I]Gibberellic acid-[N-(p-hydroxybenzyl) putrescine]amide of high specific activity, used as the immunotracer, is readily displaced by gibberellic acid methyl ester but not by free gibberellic acid. Thus, methylation of extracts prior to analysis is required. The assay is very specific; besides GA3, only the closely related GA7 is highly immunoreactive. Various gibberellins, related compounds, as well as other classes of plant hormones do not interfere with the assay. Levels of immunoreactive gibberellins (GA3, GA7) in actively growing tissues, among them cell suspension cultures of 33 different species, were determined.
61 citations
TL;DR: The observed changes in carbohydrate composition and enzyme activities indicate that GA3 induces a drastic change in potato tuber metabolism towards a pattern characteristic for the termination of the storage process.
Abstract: Potato plants (Solanum tuberosum L. cv. Ostara) were grown in aerated water culture in a controlled environment. When the tubers had reached a diameter of 1–3 cm. 14C-labelled or unlabelled gibberellic acid (GA3) was applied to the surface of the stolons at points approximately 1 crn from the developing tubers, and treatment continued for 10 days. - Significant quantities of GA3 moved into tuber tissue within 2–4 days of hormone application. This influx of GA3 was accompanied by a marked reduction in both the activity of ADPG-pyrophospharylase and the ratio ADPG-pyrophosphorylase/starch phosphorylase and an increase in the activity of UDPG-pyrophosphorylase. Starch phosphorylase activity initially increased slightly but then fell, whereas the activity of starch synthase remained constant throughout the experiment. The soluble sugar composition of the tubers changed qualitatively towards a pattern characteristic of growing stolon tips prior to tuber initiation, but there was no clear evidence of net starch degradation. Changes in the activities of the enzymes were observed prior to noticeable effects of the hormone on tuber growth rate or the development of new stolons at the tuber eyes. - GA3- treated tubers imported more 14C from labelled photosynthate than expected on the basis of growth rate. However, the capacity to convert solub#e-14C to ethaTiol-insoluble-14C (predominantly starch) was reduced in comparison with non-treated tubers. - The observed changes in carbohydrate composition and enzyme activities indicate that GA3 induces a drastic change in potato tuber metabolism towards a pattern characteristic for the termination of the storage process.
59 citations
TL;DR: It is concluded that the scutellum alone is capable of producing and mediating up to 50% of germination specific hydrolases in a commercial European malts barley, germinating at the conventional European malting temperature of 15°C.
Abstract: The relative roles of the scutellum and the aleurone layer in the production and mediation of both germination-specific α-amylase and cell wall breakdown hydrolases has been examined in vivo following treatment of barley seeds with the plant hormones gibberellic acid and abscisic acid. To facilitate entry of these exogenous hormones, a technique is presented where multiple incisions (>nicks<) are made in the outer layers of the seed prior to germination. Treatment of seeds with gibberellic acid and abscisic acid effected major changes on the pattern of hydrolase transport. The nature of the changes were such that it is concluded that the scutellum alone is capable of producing and mediating up to 50% of germination specific hydrolases in a commercial European malting barley, germinating at the conventional European malting temperature of 15°C.
50 citations
Journal Article•
45 citations
TL;DR: Applications of physiologically relevant concentrations of GA3 to the roots of tomato plants stimulates photosynthesis more consistently than that achieved by previous studies involving foliar absorption.
Abstract: This study was conducted to evaluate the effects of root applications of gibberellic acid (GA3) on photosynthesis in tomato plants grown hydroponically. Photosynthetic rates (mg CO2/dm2/hr) determined using an open infrared CO2 gas exchange system showed a 40–50% increase within 5 hr after treatment with a 1.4 µM gibberellic acid (GA3) to their roots. The effect was shown to persist for the duration of the experiment (9 days). Plants receiving pulses of 1.4 µM GA3 to the roots for 1, 4, 8 or 12 hr exhibited significantly higher photosynthetic rates than the control for 6 days following treatment. By day 9 however, there was no significant difference. Continual treatments with 1.4 µM GA3 to the roots maintained the photosynthetic rate significantly higher than the control for the duration of the experiment. Interestingly, at the lower light levels the percent stimulation was more dramatic. There was approximately a 90% increase in the photosynthetic rate at 80 µE m-2 s-1 while at saturating light conditions (560 µE m-2 s-1) there was approximately a 40% increase over the control rate. The light saturation point for both treated and control plants was 240 µE m-2 s-1. Applications of physiologically relevant concentrations of GA3 to the roots of tomato plants stimulates photosynthesis more consistently than that achieved by previous studies involving foliar absorption.
44 citations
TL;DR: The results show that exposure of barley aleurone layers to GA 3 or GA 3 +ABA, leads to an increased accumulation of mature α-amylase mRNA sequences.
41 citations
TL;DR: Gibberellic acid was found to reverse the inhibitory effect of CaCl2, causing an increase in growth rate similar to that found previously when GA3 was added to hypocotyls grown in H2O under non-flow-past conditions.
Abstract: The relationship between calcium ions and gibberellic acid (GA3)-induced growth in the excised hypocotyl of lettuce (Lactuca sativa L.) was investigated. The short-term kinetics of growth responses were measured using a linear displacement transducer. Test solutions were added either as drops to the filter paper on which the hypocotyl stood (“non-flow-past”) or by switching solution flowing past the base of hypocotyl (“flow-past”), resulting in differences in growth behavior. Drops of CaCl2 added at a high concentration (10 mM) inhibited growth within a few minutes. This inhibition was reversed by ethylenediaminetetraacetic acid (EDTA). Drops of EDTA or ethyleneglycol-bis(2-aminoethylether)-tetraacetic acid caused a rapid increase in growth rate. Growth induced by EDTA was not further promoted by GA3. A continuous H2O flow resulted in growth rates comparable to those in response to GA3. Addition of CaCl2 to the flow-past medium inhibited growth and this inhibition was reversed by a decrease in CaCl2 concentration. The growth rate was found to be a function of CaCl2 concentration. When a constant CaCl2 concentration was maintained by the flow-past medium, a shift in pH from 5.5 to 4.25 had no obvious effect on hypocotyl elongation. Gibberellic acid was found to reverse the inhibitory effect of CaCl2, causing an increase in growth rate similar to that found previously when GA3 was added to hypocotyls grown in H2O under non-flow-past conditions. We propose that gibberellin controls extension growth in lettuce hypocotyl sections by regulating the uptake of Ca2+ by the hypocotyl cells.
38 citations
TL;DR: This article showed that β-glucan solubilase in either germinating barley or in endosperm slices treated with gibberellic acid is synthesized before α-amylase and protease.
Abstract: β-Glucan solubilase in either germinating barley or in endosperm slices treated with gibberellic acid is synthesized before endo-β-glucanase, α-amylase and protease. In common with these enzymes, β-glucan solubilase is synthesized much sooner in endosperm slices than in whole grain. Gibberellic acid stimulates β-glucan solubilase synthesis in endosperm slices and most of the activity is rapidly released into the surounding medium, irrespective of whether the hormone is present. Inhibitors of RNA and protein synthesis block the formation of β-glucan solubilase.
Unlike β-glucanase, α-amylase and protease, β-glucan solubilase is present in significant quantity in untreated barley where it is concentrated in the embryo-containing half of the grain. The only β-glucan solubilase activity in barley is due to an acidic carboxypeptidase. Malt contains a small amount of a second solubilizing enzyme which appears to be an endo-β1, 3-glucanase.
34 citations
TL;DR: The data suggest that the increased growth caused by inoculation with Rhizobium strain 127E14 could be the result of increased gibberellin synthesis in lima bean nodules infected with that strain.
Abstract: Dramatic differences in the height of lima beans (Phaseolus lunatus L.) treated with two different Rhizobium strains were studied. Lima beans were grown in Perlite in the greenhouse or in a minus-N culture solution in the growth chamber. The plants were inoculated with either Rhizobium sp. (lima bean) strain 127E15, which contains the constitutive nitrate reductase activity, or strain 127E14, which lacks that activity. For up to 3 weeks, no growth differences were observed in the plants inoculated with either strain. Five weeks after inoculation, however, those plants inoculated with strain 127E14 were significantly taller and had a larger number of leaves than those inoculated with strain 127E15. The difference in plant height was the result of increased internode elongation caused by inoculation with Rhizobium sp. 127E14. This response was observed with all lima bean cultivars tested, including Henderson, Fordhook, Allgreen, and Early Thorogreen. The growth difference occurred in plants cultured in the greenhouse or in the growth chamber.No differences were observed in fresh weights of nodules, roots, axes, leaves, or flowers. The number of nodules, pods, or flowers also did not differ. Acetylene reduction rates and total N content were equal in plants inoculated with strains 127E14 or 127E15.Inasmuch as only internode length and leaf number differed between Rhizobium treatments, the response appeared to be hormone-mediated. Application of gibberellic acid to the apex of plants inoculated with strain 127E15 caused an increase in plant height similar to that observed in untreated plants inoculated with strain 127E14. Conversely, the height of plants infected with strain 127E14 was decreased by application of gibberellin synthesis inhibitors to the root system. These data suggest that the increased growth caused by inoculation with strain 127E14 could be the result of increased gibberellin synthesis in lima bean nodules infected with that strain. Whether this response was related to the absence of nitrate reductase activity in strain 127E14 is unknown.
TL;DR: Methods previously established for the propagation of cassava plants free from cassava mosaic disease have been applied to Nigerian clones and all plants raised from heat-treated meristems were free of the disease.
Abstract: Methods previously established for the propagation of cassava plants free from cassava mosaic disease have been applied to Nigerian clones. Meristem tips from diseased plants subjected to heat treatment for not less than 30 days at 35°–38°C were cultured on modified Murashige-Skoog medium. Concentration ranges of benzyladenine in combination with α-naphthalene acetic acid and gibberellic acid were investigated and, at optimal levels, 36% of the meristems regenerated. Regenerants, with callus and shoots only, were rooted with 80% efficiency by sub-culturing following a dip in a hormone rooting powder. All plants raised from heat-treated meristems were free of the disease as judged by visual inspection of the leaves, rooted explants and assay for the suspected pathogenic agent of the disease.
TL;DR: In vitro vegetative multiplication of sugarbeet was obtained by culturing of inflorescence explants and Gibberellic acid (GA3) enhanced the process.
Abstract: In vitro vegetative multiplication of sugarbeet was obtained by culturing of inflorescence explants. Subapical segments or 5-mm-long tips from nine varieties developed axillary shoots (up to 50 per tip) on a medium containing indolebutyric acid (IBA) and benzylaminopurine (BAP). Zeatin was ineffective as cytokinin. Gibberellic acid (GA3) enhanced the process. Such vegetative shoots were subsequently isolated and were each allowed to develop up to 20 supplementary axillary shoots on a multiplication medium containing IBA, BAP, and naphthaleneacetic acid (NAA). Rooting of shoots was obtained in the absence of growth regulators and plants were established.
TL;DR: The hormonal control of poly(A) polymerase activity in embryo-less wheat half-seeds by the exogenous application of gibberellic acid is reported.
TL;DR: Dry lettuce (Lactuca sativa L.) “seeds” (achenes) contain α-galactosidase at a level which is maintained in the imbibed dormant state in darkness, and both red light and gibberellic acid promote an increase in enzyme activity several hours prior to the completion of germination.
Abstract: Dry lettuce (Lactuca sativa L.) “seeds” (achenes) contain α-galactosidase (EC 3.2.122) at a level which is maintained in the imbibed dormant state in darkness. Both red light (R) and gibberellic acid promote an increase in enzyme activity several hours prior to the completion of germination. Germination and enzyme activity are not essentially linked, however, for the latter can increase while the former is inhibited. α-Galactosidase activity increases within the cotyledons and the endosperm following R stimulation, but the axis is essential to perceive the stimulus and to promote and maintain the increase in enzyme activity. A diffusible factor (or factors) is produced by and-or released from irradiated axes, and it migrates to the cotyledons (and possibly endosperm) to promote the increase in α-galactosidase activity. Gibberellic acid, particularly in the presence of benzyladenine, can replace the requirement for irradiated axes.
TL;DR: Gibberellic acid has been efficiently degraded to methyl 16-oxo-17-norgibbeerellate (8), to 16-oxy-17 norgibbederellin A1 methyl ester (9), and to (15), the 3α-epimer of (9) as discussed by the authors.
Abstract: Gibberellic acid has been efficiently degraded to methyl 16-oxo-17-norgibberellate (8), to 16-oxo-17-norgibberellin A1 methyl ester (9), and to (15), the 3α-epimer of (9). Both (9) and (15) were protected as their acetal derivatives (10) and (16) respectively and converted into the Δ2 olefin ent-10β,13-dihydroxy-16,16-ethylenedioxy-17,20 dinorgibberell-2-ene-7,19-dioic acid 7-methyl ester 19,10-lactone (11).
TL;DR: The internode elongation in plants infected with strain 127E14, its reversal by gibberellin biosynthesis inhibitors, and the accumulation of large quantities of gibb Berellin-like substances in nodulesinfected with strain127E14 support the hypothesis that root nodules may contribute gibBerellins to the host.
Abstract: Lima bean plants ( Phaseolus lunatus L.) inoculated with Rhizobium sp. strain 127E14, which lacks constitutive nitrate reductase activity, were significantly taller after 4 weeks of age than plants inoculated with strain 127E15, which contains constitutive nitrate reductase activity. Plants inoculated with either strain responded to application of 5 micrograms gibberellic acid per plant with rapid internode elongation; plants inoculated with strain 127E15 became less responsive to gibberellic acid from 3 to 5 weeks of age, while plants inoculated with strain 127E14 did not. The height of plants inoculated with strain 127E14 was reduced by 20% with application of gibberellin biosynthesis inhibitors to the roots, while height of plants inoculated with strain 127E15 was unaffected. Plants inoculated with strain 127E14 developed nodules containing 4 to 50 times greater quantities of extractable gibberellin-like substances than the nodules of plants inoculated with strain 127E15. Plants inoculated with strain 127E14 had nodules containing larger quantities of gibberellin-like substances in both the acidic and basic ethyl acetate fractions, and these differences were observed before the onset of rapid growth responsible for the difference in plant height. The internode elongation in plants infected with strain 127E14, its reversal by gibberellin biosynthesis inhibitors, and the accumulation of large quantities of gibberellin-like substances in nodules infected with strain 127E14 support the hypothesis that root nodules may contribute gibberellins to the host.
TL;DR: Of the three morphological subunits of Avena sativa stem segments examined, internodes constituted the richest source of phospholipids and sterols, yielding almost double the concentration of lipid found in the leaf-sheath.
TL;DR: The evidence presented here suggests that there is little, if any, long-term domancy in barley grass seeds and that the majority germinate in the autumn after they are shed, and very few seeds are likely to be present after a year.
Abstract: (1) In laboratory studies of seed germination, all five species of Hordeum showed some innate dormancy, which was most marked in H. glaucum and least in H. murinum. Fastest germination of fresh seeds of all species was at 10 IC or 15 IC. (2) Innate dormancy was gradually lost after dry storage of the seeds of all species, so that rate of germination, % germination and the range of constant temperatures at which germination occurred all increased. Hordeum murinum lost its innate dormancy more rapidly than did the other species. Even after prolonged storage H. glaucum seeds showed relatively low germination at constant temperatures but germination could be increased by physically damaging seeds, by treating them with gibberellic acid or by varying the temperatures to which the imbibed seeds were exposed. None of the species germinated at 35 IC but subsequent transfer to a lower temperature resulted in high percentage germination. (3) In field experiments, most seeds of all species germinated readily in response to autumn rains and, at most sites, relatively few seeds survived to germinate in the winter and spring. (4) The evidence presented here suggests that there is little, if any, long-term domancy in barley grass seeds and that the majority germinate in the autumn after they are shed. Very few seeds are likely to be present after a year. If barley grass is controlled effectively so that no new seeds are shed, then there should be little problem the following year although a small number of plants may still need to be controlled.
TL;DR: Present in many plants, especially during germination, growth and seed maturation, gibberellins may be proximate chemical cues to reproduction in some herbivores, and may act as a feedback mechanism between plant and herbivore in some models of demographic cycles.
Abstract: The plant hormone gibberellic acid (GA3), given in the drinking water to field-caught Mus musculus in the laboratory, almost doubled the proportion of females producing litters. No increase was detected in litter size or number of litters produced by breeding females. In a further experiment, the proportion of females coming into oestrus was more than doubled by treatment with GA3. Present in many plants, especially during germination, growth and seed maturation, gibberellins may be proximate chemical cues to reproduction in some herbivores, and may act as a feedback mechanism between plant and herbivore in some models of demographic cycles.
TL;DR: Young pepper plants treated with gibberellic acid (GA3) before the initiation of floral organs produced abnormalities in flowers subsequently formed, and GA3 caused abnormalities in pollen development and induced the carpelization of stamens.
Abstract: Young pepper plants treated with gibberellic acid (GA3) before the initiation of floral organs produced abnormalities in flowers subsequently formed. The development of petals and stamens was affected by GA3, but sepals and the gynoecium were insensitive to the treatment. The effect on petals was on the unrolling of organs but stamen development was affected more dramatically. GA3 caused abnormalities in pollen development and induced the carpelization of stamens. The expression of feminization of stamens ranged from the production of a few external ovules to a complete transformation of a stamen to a carpel with ovary, style, and stigma. In some instances, the growth of stamens was also inhibited. GA3 also induced supernumerary organs in flowers; all of which were "carpel-like." These and other observations are discussed in relation to the hormonal status and the genetic make-up of plants.
TL;DR: A culture medium and culture conditions are described that enable generative cell division and sperm formation to occur in a large proportion (greater than 70%) of the pollen tubes of Tradescantia paludosa within six to eight hours of culture of pollen.
Abstract: A culture medium and culture conditions are described that enable generative cell division and sperm formation to occur in a large proportion (greater than 70%) of the pollen tubes of Tradescantia paludosa within six to eight hours of culture of pollen. The nature of the nitrogen source, speed of shaking, and ratio of pollen to medium are important parameters in determining the extent of sperm formation. Addition of the plant hormones indole acetic acid, gibberellic acid, and kinetin to the growth medium does not influence generative cell division.
TL;DR: Application of growth substances, notably TIBA and daminozide to the apex and benzyladenine and gibberellic acid to the inflorescences, can be shown to modify competition and enhance reproductive at the expense of vegetative growth with consequent implications for yield.
TL;DR: The content and distribution of absicisic acid and gibberellic acid in potato tubers differing in growth rates and sizes has been determined in this paper, and no significant correlation has been found between the growth rate and the concentration of ABA and GA in tuber tissue, but the phytohormone content per tuber increased proportionally with tuber size.
Abstract: The content and distribution of absicisic acid (ABA) and gibberellic acid (GA) in potato tubers differing in growth rates and sizes has been determined. No significant correlation has been found between the growth rate and the concentration of ABA and GA in tuber tissue, but the phytohormone content per tuber increased proportionally with tuber size. GA was distributed fairly uniformly throughout the tissue whereas ABA tended to be concentrated in the tuber apex.
TL;DR: In leaf segments of barley (Hordeum vulgare L. cv. Mozoncillo), the cytokinin specificity for retarding the loss of phosphate is different from that of retardingThe loss of chlorophyll.
Abstract: In leaf segments of barley (Hordeum vulgare L. cv. Mozoncillo), the cytokinin specificity for retarding the loss of phosphate is different from that of retarding the loss of chlorophyll. Some cytokinins require the simultaneous application of gibberellins to delay the loss of phosphate. Although both chlorophyll and phosphate losses occur in senescence, they are apparently controlled by cytokinins through different mechanisms.
TL;DR: Probit analysis was used to determine the parameters of the germinating population of lettuce seed and it was shown that with light induced germination the Germinating populations were the same.
Abstract: Probit analysis was used to determine the parameters of the germinating population of lettuce seed. Seeds were induced to germinate under different conditions and it was shown that with light induced germination the germinating populations were the same. However, when gibberellic acid (GA3) was the inductive agent then the germinating populations were not the same being concentration dependent. – This type of analysis offers a rigorous comparison of different inductive treatments.
TL;DR: It appears that although GA inhibits shoot meristem initiation from potato tuber discs, it is required for shoot development once meristems are initiated.
Abstract: The formation of adventitious shoots from potato tuber discs explanted onto a modified Murashige and Skoog (MS) medium containingN
6-benzylaminopurine (BAP) (3.0 mg/l), and α-naphthaleneacetic, acid (NAA) (0.01 mg/l), was affected by gibberellic acid (GA). The presence of GA in the explant medium was required for shoot formation and 3×10−10
M GA appeared optimum. However, microscopic examination of the tissue protuberances on the surface of the tuber discs from which shoots arose revealed that GA inhibited the formation of shoot meristems. Tuber discs cultured for 6 wk on MS medium containing BAP and NAA without GA did not initiate adventitious shoots that could be determined visually, but microscopic examination of the tissue protuberances revealed the presence of numerous shoot meristems. Subsequent transfer of these tuber discs to medium with GA but without BAP or NAA resulted in the formation of shoots from 100% of the recultrued dises. Thus it appears that although GA inhibits shoot meristem initiation from potato tuber discs, it is required for shoot development once meristems are initiated.
TL;DR: The close correlation between increase in growth of an internode in response to gibberellic acid and the decrease in silicon content of that internode indicated a dilution effect of growth on the amount of silicon rather than a direct effect of gibbERELLic acid on silicon deposition.
Abstract: The effect of gibberellic acid on the content and distribution of silicon in the stem, leaf sheath, and leaf lamina of sugarcane was analyzed in relation to the effect of gibberellic acid on stem growth. Silicon content was measured by neutron activation analysis, and its distribution was followed by scanning electron microscopy and X-ray analysis. Foliarly applied gibberellic acid increased stem length and fresh weight and decreased silicon content. Gibberellic acid treatments had little or no effect on growth or silicon content of leaf laminae or sheaths. The close correlation between increase in growth of an internode in response to gibberellic acid and the decrease in silicon content of that internode indicated a dilution effect of growth on the amount of silicon rather than a direct effect of gibberellic acid on silicon deposition. This conclusion was supported by scanning electrom microscopy, X-ray map photos, and counts of silica cells per unit of epidermis area.