Showing papers on "Gibberellic acid published in 1990"

The preparation in vitro of chrysanthemum for transplantation to soil

Abstract: Plantlets of Chrysanthemum x morifolium were grown from nodal sections in cellulose plugs which were saturated with liquid rooting medium. Inclusion of 0.5–4.0 mg l−1 paclobutrazol in the rooting medium led to a reduction in wilting when plantlets were transferred to compost and exposed to an atmosphere of reduced humidity. Smaller stomatal apertures, increased epicuticular wax, whortened stems and thickened roots were observed and may each have contributed to this reduction in wilting. Paclobutrazol treatments also increased chlorophyll concentration per unit area of leaf. Gibberellic acid had the reverse effect to that of paclobutrazol on most of the characters which were investigated.

Comparative indole-3-acetic Acid levels in the slender pea and other pea phenotypes.

Abstract: Free indole-3-acetic acid levels were measured by gas chromatography-mass spectrometry in three ultra-tall `slender9 Pisum sativum L. lines differing in gibberellin content. Measurements were made for apices and stem elongation zones of light-grown plants and values were compared with wild-type, dwarf, and nana phenotypes in which internode length is genetically regulated, purportedly via the gibberellin level. Indole-3-acetic acid levels of growing stems paralleled growth rates in all lines, and were high in all three slender genotypes. Growth was inhibited by p -chlorophenoxyisobutyric acid, demonstrating the requirement of auxin activity for stem elongation, and also by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. It is concluded that the slender phenotype may arise from constant activation of a gibberellin receptor or transduction chain event leading directly or indirectly to elevated levels of indole-3-acetic acid, and that increased indole-3-acetic acid levels are a significant factor in the promotion of stem elongation.

The development of dormancy in bulblets of Lilium speciosum generated in vitro. 1. The effects of culture conditions.

Abstract: We have studied the effect of various in-vitro conditions on dormancy of bulblets generated on scale explants of Lilium speciosum Thunb. cv. ‘Rubrum’ nr. 10. The bulblets were harvested after 11 weeks of culture. Dormancy was measured by determining the percent emergence in soil of viable, non-cold-treated bulblets. A study of the physical conditions showed that temperature had a strong effect on the induction of dormancy (15°C induced hardly any dormancy; 25°C induced a high level of dormancy), whereas short or long day and light or dark had no effect. Of the medium components, a low concentration of sucrose (1 gl−1 or less) or a high concentration of gibberellic acid (1 mg 1−1) reduced the level of dormancy. Application of various concentrations of abscisic acid, 6-benzylaminopurine, α-naphthaleneacetic acid, indole-3-acetic acid, 2,3,5-triiodobenzoic acid or a Murashige and Skoog macro- and microelement mixture did not affect the dormancy status.

Gibberellic Acid Regulates Cell Wall Extensibility in Wheat (Triticum aestivum L.).

Abstract: Mutations (Rht genes) blocking sensitivity to gibberellic acid (GA) were used to examine phytohormone mediated cell wall expansion in wheat (Triticum aestivum L.). Irreversible extensibility of immature leaf segments, as determined by stress/strain (instron) measurements, declined with Rht gene dose. Exogenous GA3 significantly increased wall extensibility in the nonmutant controls but had no effect on the near-isogenic GA-insensitive genotypes. Furthermore, ancymidol, an inhibitor of gibberellin biosynthesis, diminished wall extensibility in the nonmutant control. Extensibility of immature segments was highly correlated with mature leaf sheath length (R = +0.95). The results indicate that wall yielding properties of expanding wheat leaves are associated with leaf cell expansion potential and that GA is involved in the determination of those properties.

Effects of Kinetin and Gibberellic acid in Overcoming High Temperature and Salinity (NaCl) Stresses on the Germination of Barley and Lettuce Seeds

Abstract: KABAR K. & BALTEPE S. 1990. Effects of kinetin and gibberellic acid in overcoming high temperature and salinity (NaCl) stresses on the germination of barley and lettuce seeds. Phyton (Horn, Austria) 30 (1): 65-74, 2 figures. English with German summary. Gibberellic acid (GA3), kinetin, and a combination of these two hormones applied axternally to dry seeds of barley (Hordeum distichon L.) and lettuce (Lactuca sativa L.) removed high temperature and/or salinity (NaCl) stresses on the germination of these seeds to varying extents. Kinetin alone had more effect on lettuce, while GA3 was more effective on barley. However, as the germination temperature and salt levels were increased, the synergistic effect of GA3 and kinetin combination was required. The application of high temperature stress (35° C) was found as reversible in lettuce, and as irreversible in barley. Nevertheless, the salinity stress was osmotic and reversible in both seeds.

Distinction between the Responses of Developing Maize Kernels to Fluridone and Desiccation in Relation to Germinability, α-Amylase Activity, and Abscisic Acid Content

Abstract: Developing kernels of the maize (Zea mays) hybrid W64A x W182E germinated precociously following fluridone treatment. Likewise, following premature drying, the kernels germinated upon subsequent rehydration. Tolerance of the aleurone layer to premature desiccation considerably preceded that of the embryo. The increase in α-amylase activity following premature drying was substantial and was equal to, or exceeded, the increase which occurred following normal maturation drying. In contrast, there was only a small increase in enzyme activity, regardless of the concentration of the supplied gibberellic acid, following fluridone treatment. Both fluridone and drying cause a decrease in abscisic acid content within the developing kernels. While this decline in growth regulator may permit kernels to germinate, alone this is not sufficient to permit an increase in α-amylase activity. Thus drying is necessary to sensitize the aleurone layer to gibberellin, and thereby elicit enzyme synthesis. For this tissue to achieve its full potential to produce α-amylase, it must not only be free of the inhibitory effects of abscisic acid, but it must also be competent to respond to gibberellin.

Stamens and Gibberellic Acid in the Regulation of Flavonoid Gene Expression in the Corolla of Petunia hybrida

Abstract: Stamen removal at an early stage of flower development inhibits anthocyanin synthesis and chalcone flavanon isomerase (CHI) enzyme activity in corollas of Petunia hybrida. The inhibition can be overcome by gibberellic acid (GA3) application. Gibberellin also induces anthocyanin synthesis in detached, young green corollas, grown in vitro in a sucrose medium and promotes CHI enzyme activity. Western blot analysis indicates an increase in chalcone synthase (CHS) and CHI protein levels following GA3 treatment in both the in vivo and the in vitro systems. Northern blot analysis shows a higher level of steady-state mRNAs for CHS and CHI 24 hours after GA3 application. In corollas from a transgenic plant containing a β-glucuronidase gene driven by a CHI promoter, a sixfold increase of β-glucuronidase activity was measured following GA3 application. The mode of action of stamens and GA3 control over flavonoid gene expression is discussed.

Micropropagation of Eucalyptus tereticornis Smith.

Abstract: Axillary shoot bud multiplication has been achieved in Eucalyptus tereticornis Smith. using explants from different regions of 8–10 years old elite trees, growing in the field. Results showed that addition of NAA at 0.1 mgl-1 and BAP at 1.0 mgl-1 to modified MS medium induced maximum number of shoot buds. For inducing axial growth in regenerated bud promordia, the hormone concentration of the medium was lowered. The addition of charcoal and gibberellic acid to the medium were beneficial. Rooting was best in Knop's medium containing 1.0 mgl-1 IBA. The key factor in root induction was primarily a dark incubation for a short period. The percentage of both rooting of shoots and survival of the rooted shoots was 60–80.

Relation between relative growth-rate, endogenous gibberellins, and the response to applied gibberellic-acid for plantago-major

Abstract: Relationships between relative growth rate (RGR), endogenous gibberellin (GA) concentration and the response to application of gibberellic acid (GA(3) ) were studied for two inbred lines of Plantago major L., which differed in RGR. A4, the fast-growing inbred line, had a higher free GA concentration than the slow-growing W9, as analyzed by enzyme immunoassay. GA(3) application increased total plant weight and RGR(3) particularly for the slow-growing line. Chlorophyll a content and photosynthetic activity per unit leaf area were decreased, while transpiration rate was unaffected by GA(3) application. The increase in RGR by GA(3) application was associated with an increased leaf weight ratio; specific leaf area and percentage of dry matter in the leaves were only temporarily affected. Root respiration rate per unit dry weight was unaffected. The correlation between low RGR, low GA concentration and high responsiveness to applied GA(3) supports the contention that gibberellins are involved in the regulation of RGR. However, the transient influence of GA(3) application on some growth components suggests the involvement of other regulatory factors in addition to GA.

Genetic Analysis of the Role of Gibberellin in the Red Light Inhibition of Stem Elongation in Etiolated Seedlings

Abstract: Red light causes a reduction in the extension growth of dark-grown seedlings The involvement of gibberellin in this process was tested by screening a number of gibberellin synthesis and gibberellin response mutants of Pisum sativum L for the kinetic response of stem growth inhibition by red light Gibberellin deficient dwarfs, produced by mutant alleles at the Le, Na, and Ls loci, and gibberellin response mutants produced by mutant alleles at the La and Cry2, Lka, and Lkb loci were tested Extension growth of expanding third internodes of dark-grown seedlings was recorded with high resolution using angular position transducers Seedlings were treated with red light at a fluence rate of 4 micromoles per square meter per second either continuously or for 75 seconds, and the response was measured over 9 hours With certain small exceptions, the response to the red light treatments was similar in all the mutants and wild types examined The lag time for the response was approximately 1 hour and a minimum in growth rate was reached by 3 to 4 hours after the onset of the light treatment Growth rate depression at this point was about 80% Seedlings treated with 75 seconds red light recovered growth to a certain extent Red/far-red treatments indicated that the response was mediated largely by phytochrome The similar responses to red light among these wild-type and mutant genotypes suggest that the short-term (ie 9 hour) response to red light is not mediated by either a reduction in the level of gibberellin or a reduction in the level or affinity of a gibberellin receptor

Regulation of potato meristem development by jasmonic acid in vitro.

Abstract: The influence of jasmonic acid (JA) on differentiation of meristems of the potato,Solanum tuberosum cv. Vesna, was investigated in vitro. Meristems were grown on Murashige and Skoog (MS) medium supplemented with indole-3-acetic acid (IAA) (10 μM), kinetin (10 μM), gibberellic acid (3 μM), as modified by Bang. Addition of JA in concentrations of 0.5–10 μM increased the number of meristems that developed into buds, particularly in meristems isolated from shoots grown from tubers in the dark. JA had no noticeable effect on meristems from germs grown in light. All added concentrations of JA retarded callus and root formation. The inhibitory effect on rhizogenesis disappeared immediately after transfer of the developed buds to medium without JA.

Solid state fermentation : physical and nutritional factors influencing gibberellic acid production

Abstract: The production of gibberellic acid (GA3) was found to be influenced by physical and nutritional factors. The nutritional factors studied were the urea nitrogen and MgSO4 concentrations, whereas the physical factors were moisture content, autoclaving time, inoculum ratio and moist medium to culture flask volume ratio. The yield of GA3 was improved 2.9 times by judicious selection of these parameters. Thus, the increase in GA3 yield in the wheat bran medium reduces the expense on medium and further leads to reduction of the overall cost of production.

Screening of Basidiomycetes and Ascomycetes for Plant Growth Regulating Substances. Introduction of the Gibberellic Acid Induced de-novo Synthesis of Hydrolytic Enzymes in Embryoless Seeds of Triticum aestivum as Test System

Abstract: Abstract A new test system for the detection of plant growth regulating activities was successfully employed. In a screening for inhibitors of the gibberellic acid controlled synthesis of hydrolytic enzymes in embryoless wheat seeds (Triticum aestivum) 160 cultures of ascomycetes and basidiomycetes were tested. In the extracts of two cultures inhibitory activities were detected. From fermentations of a Hypholoma-species (basidiomycetes) 3,5-dichloro-4-methoxybenzyl alcohol was isolated as the active principle. Galiellalactone and two other new phytotoxins were isolated from cultures of the ascomycete Galiella rufa. At concentrations of 50 μg/ml all four compounds inhibited the de-novo synthesis of α-amylases, proteases, and phosphatases. Further investigations on the mode of action revealed, that all four metabolites interfere with early steps of the biosynthetic path ways induced by gibberellic acids. In vivo, the germination of the seeds of several plants was inhibited by these compounds.

A pleiotropic mutation results in cross-resistance to auxin, abscisic acid and paclobutrazol

Abstract: Mutant lines of Nicotiana plumbaginifolia resistant to the synthetic auxins 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA) were isolated as germinating seedlings on selective medium. In each case, resistance was conferred by a single recessive nuclear mutation at one of 3 loci designated iba1, iba2 and iba3. Labelling studies with 14C NAA suggest that resistance was not due to changes in the uptake or metabolism of NAA. Plants homozygous for the iba1 mutation exhibit a syndrome of atypical germination and growth suggestive of a defect in the biosynthesis, metabolism or localization of abscisic acid. Wild-type seeds treated with gibberellin exhibit the same syndrome, including resistance to NAA and IBA. On the basis of these observations, we propose that auxin toxicity in seeds may be mediated by a block in gibberellin biosynthesis.

Comparison of Biological Activities of Gibberellins and Gibberellin-Precursors Native to Thlaspi arvense L.

Abstract: Field pennycress (Thlaspi arvense L.) is a winter annual weed with a cold requirement for stem elongation and flowering. The relative abilities of several native gibberellins (GAs) and GA-precursors to elicit stem growth were compared. Of the eight compounds tested, gibberellin A1, (GA1), GA9, and GA20 caused stem growth in noninduced (no cold treatment) plants. No stem growth was observed in plants treated with ent-kaurene, ent-kaurenol, ent-kaurenoic acid, GA53, or GA8. Moreover, of the biologically active compounds, GA9 was the most active followed closely by GA1. In thermoinduced plants (4-week cold treatment at 6°C) that were continuously treated with 2-chlorocholine chloride to reduce endogenous GA production, GA9 was the most biologically active compound. However, the three kaurenoid GA precursors also promoted stem growth in thermoinduced plants, and were almost as active as GA20. No such increase in activity was observed for either GA[unk] or GA53. The results are discussed in relation to thermoinductive regulation of GA metabolism and its significance to the initiation of stem growth in field pennycress. It is proposed that thermoinduction results in increased conversion of ent-kaurenoic acid to GAs through the C-13 desoxy pathway and that GA9 is the endogenous mediator of thermoinduced stem growth in field pennycress.

Interactive effect of NaCl salinity and gibberellic acid on shoot growth, content of abscisic acid and gibberellin-like substances and yield of rice (Oryza sativa L. var GR-3)

Abstract: When rice (Oryza sativa L. var GR-3) plants were subjected to salt stress (12 dS/m) the extension growth and dry weight of the shoot system as well as the content of chlorophyll and gibberellin-like substances were found to be markedly reduced. Contrarily, the level of abscisic acid in the shoot system registered a rapid and massive increase in response to salinity. Compared to control, salt stressed plants showed higher concentration of Na+ and Cl− and lower concentration of K+ in the leaf tissue. Salinization also resulted in a considerable reduction in grain yield. Exogenous application of gibberellic acid (10 ppm) significantly increased the growth and yield of salt stressed plants. Gibberellic acid treatment reduced the net accumulation of Na+ and Cl− and maintained high level of K+ in the leaves of salinized plants. A significant fall in the content of abscisic acid and a marked increase in the amount of chlorophyll were also noticed in salinized plants in response to gibberellic acid administration. These results suggest that gibberellic acid improved the growth and yield of stressed rice plants presumably by hormonising the ionic status of the plants as well as by modulating the endogenous level of abscisic acid.

Germination stimulation in wild oats (Avena fatua L.) by synthetic strigol analogs and gibberellic acid.

Abstract: At concentrations of 0.01–1 mM, five synthetic multiring analogs of strigol were effective germination stimulants of intact and dehulled wild oat (Avena fatua L.) seeds. The effect was concentration-dependent and equaled or exceeded that produced by equimolar gibberellic acid (GA3). The most effective strigol analog treatments induced 55–80% germination within 7 days in intact wild oat seeds and resulted in 63–86% germination and normal seedling growth over 14 days. Intact wild oat controls germinated 14% after 14 days. The stimulation of wild oat germination by these synthetic strigol analogs demonstrates that these compounds, initially developed as germination stimulants for the seeds of the parasitic weed, witchweed (Striga asiatica L. Kuntz.), have bioregulatory activity in dormant seeds of monocots, as well as dicots. None of the compounds tested significantly affected the germination of nondormant cultivated oat seeds (Avena sativa L.). The commonly used dispersal agent, Tween 20 (0.1%), was found to inhibit germination of cultivated oats, alone and in the presence of 2% acetone.

Growth and development of Brassica genotypes differing in endogenous gibberellin content. I. Leaf and reproductive development.

Abstract: Leaf and reproductive development were compared in 3 rapid cycling Brassica rapa genotypes grown for 4 weeks under greenhouse conditions. The dwarf mutant, rosette (ros), is gibberellin (GA)-deficient, while the tall mutant, elongated internode (ein), has enhanced endogenous GA levels. Germination was delayed in ros and a selection of a more severe form of ros, named dormant (do), has even more retarded germination and some seeds entirely fail to germinate. Seeds of do and ros respond to exogenous GA, by rapid germination. The 3 genotypes, ros, normal and ein, displayed similar developmental sequences, although floral bud formation and subsequent floral development and anthesis were delayed in ros. Conversely, anthesis was slightly accelerated in ein. Individual leaf areas were reduced in both ros and ein relative to the normal genotype, but leaf numbers were similar in all 3 genotypes. Differences in leaf morphology (heterophylly) were also observed; the normal genotype and ein plants possessed uniform leaf shapes and relatively smooth leaf margins, although petiole length was increased in ein. The mutant ros had scalloped leaf margins and convoluted leaf blades in addition to shortened petioles. These phenotypes suggest a role for GA in the regulation of germination and reproductive and leaf development in Brassica.

Regulation of α-amylase formation and gene expression in the developing wheat embryo

Abstract: Embryos in developing wheat (Triticum aestivum L., cv. Sappo) grains (15–40 d post anthesis, dpa) contain no detectable α-amylase. When isolated from the grain they produce the enzyme even though they do not germinate. Younger (15 dpa) and older (45 dpa) embryos produce only a group of isozymes of low isoelectric point (pI): at intermediate ages low-pI and high-pI groups appear. The low-pI group is formed first, about 6 h after isolation, followed by the high-pI group at 16h. The formation of high-pI isoenzymes is prevented by abscisic acid and osmoticum, which also suppress the accumulation of high-pI mRNA. Almost all of the low-pI isoenzymes are unaffected by these two factors. Low-pI mRNA transcripts are present in embryos in situ but are not translated. Translation occurs when embryos are isolated, though there appears to be no further accumulation of low-pI mRNA. Addition of gibberellic acid to isolated embryos causes a great increase in accumulated high-pI mRNA, but only a small increase in low-pI message. Added gibberellic acid enables younger and older embryos to produce high-pI isoenzymes. The regulation of α-amylase gene expression and enzyme formation in developing embryos in situ is discussed in the light of these findings.

Effects of Some Antioxidants on in Vitro Rooting of Apple Shoots

Abstract: In vitro-proliferated shoots of 'Delicious' and 'Starkspur Red' apples (Malus domestica Borkh.) were submitted for 1 week to root induction in the dark with their basal parts in liquid medium containing 1.5 µM IBA and 43.4 mM sucrose. The shoots were transferred to root initiation and root elongation medium made up of plugs wetted with half-strength Lepoivre salts. When antioxidants, such as PVP, GH, 2-Me, and DIECA, were added to the liquid induction medium, the percentages of rooting usually decreased. In contrast, if the antioxidants PVP and citric acid were added in the initiation-elongation medium, the percentages of rooting increased. The results agree with the finding of other researchers who proposed a rapid increase in peroxidase activity during root induction followed by a fast decline during rooting initiation as a marker for good rooting responses. Moreover, the use of antioxidants both in induction and in initiation-el ongation had no effect on number and length of roots. Chemical names used: polyvinylpyrrolidone-40 (PVP); glutathione reduced (GH); 2-mercaptoeth- anol (2-Me); diethyldithiocarbamic acid, sodium salt trihydrate (DIECA); N- (phenyl- methyl) 1 H- purin-6-amine (BA); 1 H- indole-3-butyric acid (IBA); gibberellic acid (GA3). In several tree species, rooting remains one of the most critical steps of the micropro- pagation technique. Moncousin and Gaspar (1983) reported that in Cynara scolymus, a herbaceous plant, high rooting responses corresponded to increases in peroxidase (EC 1.11.1.7) activity during induction and a rapid decrease in the same enzymatic activity dur- ing initiation-elongation phase. Usually variations in peroxidase activity and rooting responses have been obtained by application of light, auxin, temperature, and/ or phenols at the proper time (Debergh, 1987;

Gibberellic acid causes earlier flowering and synchronizes fruit ripening of coffee

Abstract: The effect of 100 mgl−1 gibberellic acid (GA3) on flowering and fruit ripening synchrony, fruit set, fruit fresh weight, and vegetative growth were studied for different size classes of coffee (Coffea arabica L. cv. Guatemalan) flower buds. Flower buds that were > 4 mm, but not developed to the candle stage at the time of GA3 treatment, reached anthesis 20 days earlier than the controls, and their development was independent of precipitation, unlike the controls. Fruit from buds that were treated with GA3 at the candle stage showed earlier and more synchronous ripening than the control, although no differences in flowering were found during anthesis. Buds that were smaller than 4 mm at the time of treatment did not respond to GA3 applications. Treatment with GA3 did not affect fruit set, fresh weight of fruits, or vegetative shoot growth.

Callus induction and plant regeneration of American ginseng.

Abstract: Friable embryogenic callus of American ginseng (Panax quinquefolium L.) was induced from root pith on Murashige and Skoog medium supplemented with 2 mg 2,4-D and 1 mg KIN/liter. Optimal callus growth occurred on medium containing 1.5 mg dicamba/liter. Plants were regenerated on MS medium supplemented with various concentrations of plant growth regulators (PGRs); the best PGR combination was 0.5 mg IBA and 0.1 mg NAA/liter. Chemical names used: (2,4 -dichlorophenoxy) acetic acid (2,4-D); 3,6-dichloro-o-anisenic acid (dicamba); 6-benzylaminopurine (BA); gibberellic acid (GA); indole-3-butyric acid (IBA); kinetin (KIN); and naphthaleneacetic acid (NAA). The root of ginseng (Panax spp.), culti- vated in northern China, Korea. the United States, Canada, and the - Soviet - Union, has