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Showing papers on "Gibberellic acid published in 1993"


Journal ArticleDOI
TL;DR: The expression of single rol genes of the TL-DNA of Agrobacterium rhizogenes strain A4 in transgenic tobacco and potato plants alters the internal concentrations of, and the sensitivity to, several plant hormones.
Abstract: Summary The expression of single rol genes of the TL-DNA of Agrobacterium rhizogenes strain A4 in transgenic tobacco (Nicotiana tabacum L.) and potato (Solanum tuberosum L.) plants alters the internal concentrations of, and the sensitivity to, several plant hormones. The levels of immunoreactive cytokinins, abscisic acid, gibberellins and indole-3-acetic acid were analysed in tissues of the apical shoots, stems, leaves, roots and undifferentiated callus tissue. The addition of the dominant and morphogenetically active rolA, rolB, or rolC genes resulted in alterations in the content of several hormones. rolC overexpression in particular led to an up to fourfold increase in the content of isopentenyladenosine, dihydrozeatin riboside and trans-zeatin riboside-type cytokinins in potato plants. This increase correlated well with different levels of expression of the rolC gene in different transgenic plants. Furthermore it was shown that the dwarfism of P35s-rolC transgenic tobacco and potato plants is correlated with a 28–60% reduction of gibberellic acid A1 concentration in apical shoots. Exogenous addition of gibberellic acid completely restored stem elongation in P35s-rolC transgenic plants. Apical shoots of dwarf rolA transgenic tobacco plants also contained 22% less gibberellic acid A1 than control plants, but growth cannot be restored completely by exogenously added gibberellic acid. Similarly, the sensitivity of transgenic tobacco seedlings or callus tissues towards different phytohormone concentrations can be altered by the expression of single rol genes. The overexpression of the rolC gene in seedlings led to an altered response to auxins, cytokinins, abscisic acid, gibberellic acid and the ethylene precursor 1-aminocyclopropane-carboxylic acid. The overexpression of the rolB gene in tobacco calli led to necrosis at lower auxin concentrations than in the wild-type, while other parameters of auxin action, like the induction of cell growth, remained unchanged.

170 citations


Journal ArticleDOI
TL;DR: From aseptically grown Artemisia annua plantlets, shoot cultures were initiated and attempts were made to improve the artemisinin production by varying the medium composition through addition of gibberellic acid or casein hydroly-state.
Abstract: From aseptically grown Artemisia annua plantlets, shoot cultures were initiated. Using different concentrations of auxine, cytokinine and sucrose, a suitable culture medium was developed, with respect to the growth of the shoots and their artemisinin accumulation. Nitrate concentration and conductivity appeared to be suitable growth parameters. The artemisinin content was measured gas chromatographically. The shoot cultures were maintained in the developed standard medium, consisting of a half concentration of MS-salts with vitamins, 0.2 mg l-1 BAP, 0.05 mg l-1 NAA and 1% sucrose. The growth of the shoots and the artemisinin content remained stable for a longer period. They showed considerable photosynthetic activity and generally contained ca. 0.08% artemisinin on a dry weight basis. The highest artemisinin content found was 0.16% in the above mentioned standard medium, but also on the same medium with 0.5% sucrose. Attempts were made to further improve the artemisinin production by varying the medium composition through addition of gibberellic acid or casein hydroly-state; by omitting plant growth regulators; by precursor feeding, i.e. mevalonic acid; by influencing the biosynthesis routing through inhibition of the sterol synthesis by miconazole, naftifine or terbinafine; by changing gene expression with 5-azacytidine or colchicine; and by elicitation, using cellulase, chitosan, glutathione or nigeran. Enhanced artemisinin production was found with 10 mg l-1 gibberellic acid, 0.5 g l-1 casein hydrolysate, 10 mg l-1 or 20 mg l-1 naftifine. Relative increases of 154%, 169%, 140% and 120% were found, respectively. Other additions caused the growth to cease and the artemisinin contents to drop.

117 citations


Journal ArticleDOI
01 Aug 1993-Planta
TL;DR: It is found that α-amylase mRNA fails to accumulate in embryoless barley half-seeds treated with gibberellic acid, indicating that the action of anoxia may be at the transcriptional level.
Abstract: The effect of anoxia on the induction of α-amylase in seeds of rice (Oryza sativa L.), wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), oat (Avena sativa L.) and rye (Secale cereale L.) was studied. The results showed that only rice is able to synthesize α-amylase under anoxia, while other cereal seeds fail to produce the enzyme and do not germinate. The inhibitory effect of anoxia on α-amylase induction is concluded to be due to the inability of cereal seeds to respond to gibberellic acid under conditions of total oxygen deprivation. Rice appears to be an exception to this rule among the cereal seeds tested. We found that α-amylase mRNA fails to accumulate in embryoless barley half-seeds treated with gibberellic acid, indicating that the action of anoxia may be at the transcriptional level.

107 citations


Journal ArticleDOI
01 Aug 1993-Planta
TL;DR: It is shown that gibberellins are morphogenetically active substances, not only in shoots but also in roots of maize, and that the meristem and immediate post-mitotic zone were the targets of gibBerellin deficiency.
Abstract: The role of gibberellins and cortical microtubules in determining the polarity of cell growth in the root cortex of maize (Zea mays L.) was examined. Inhibition of gibberellin biosynthesis, either naturally through mutation (d5 mutant) or by means of chemicals such as 2S,3S paclobutrazol, caused thickening of root apices and increased their starch content. Immunofluorescence microscopy of cortical microtubules, coupled with a comparison of cell widhts, lengths and shapes, indicated that the meristem and immediate post-mitotic zone were the targets of gibberellin deficiency. Cortical cells in these regions were impaired in their ability to develop highly ordered transversal arrays of cortical microtubules. Consequently, the cells became wider and shorter. Application of gibberellic acid re-established the arrangements of cortical microtubules and the polarity of cell growth characteristic for roots having normal levels of gibberellins, it also decreased the starch content. These results indicate that gibberellins are morphogenetically active substances, not only in shoots but also in roots of maize.

94 citations


Journal ArticleDOI
TL;DR: XET activity correlated with GA3-enhanced length in pea internodes; the possibility that this represents a causal relationship is discussed.
Abstract: Xyloglucan endotransglycosylase (XET) activity extractable from internodes of tall and dwarf varieties of pea (Pisum sativum L.) was assayed radiochemically using tamarind seed xyloglucan as donor substrate and an oligosaccharidyl-[3H]alditol as acceptor substrate. Internodes I and II showed little elongation during the period 15 to 21 d after sowing; XET activity remained relatively constant and was unaffected by exogenous gibberellic acid (GA3). A single application of GA3 to the dwarf genotype resulted in a small enhancement of elongation in internode III between d 17 and 21 and caused a small increase in XET activity in internode III. Repeated applications of GA3 caused internode V to elongate between d 20 and 26, to the same extent as in the tall variety, and concomitantly led to greatly elevated XET activity (expressed per unit fresh weight, per unit of extractable protein, and per internode). Thus, XET activity correlated with GA3-enhanced length in pea internodes; the possibility that this represents a causal relationship is discussed.

86 citations


Journal ArticleDOI
TL;DR: The maturation of embryos was significantly affected by pH, photoperiod, abscisic acid and genotype, and all regenerated plants showed normal morphological characteristics.
Abstract: Somatic embryogenesis and plant regeneration were obtained from immature leaflet callus of chickpea. Numerous globular embryos developed on the surface of callus on Murashige and Skoog's (1962) medium containing 25 μM 2,4-dichlorophenoxyacetic acid. These globular embryos differentiated into mature somatic embryos upon removal of 2,4-dichlorophenoxyacetic acid. The maturation of embryos was significantly affected by pH, photoperiod, abscisic acid and genotype. Callus continued to produce somatic embryos for over 8 subcultures at 4 week intervals. Two per cent of the embryos formed plants on medium containing 15 μM gibberellic acid and 1 μM indole-3-butyric acid. Desiccation of embryos for a period of 3 d increased their rate of conversion into plants from 0.9 to 2.8%. All regenerated plants showed normal morphological characteristics.

72 citations


Journal ArticleDOI
TL;DR: In young and fully developed leaves of rolA and P35S-rolA transgenic clones a 40–60% reduction of immunoreactive gibBerellin A1 was found, as compared to wild-type leaves, which suggests that the reduction of gibberellic acid content is indirectly but causally involved in rolC-induced alterations of stem elongation and planar leaf blade growth.
Abstract: The rolA gene of the TL-DNA of Agrobacterium rhizogenes Ri-plasmid plays a major role in establishing the hairy root syndrome in transgenic plants. Transgenic tobacco plants (Nicotiana tabacum L.) expressing constitutively the rolA gene under the transcriptional control of the 35S RNA promoter show pronounced phenotypical alterations. P35S-rolA transgenic tobacco plants are characterized by stunted growth, dark green wrinkled leaves with an altered length-to-width ratio, condensed inflorescences, retarded onset of flowering, a reduced number of flowers and shortened styles. To investigate whether the pleiotropic alterations of growth and development are linked to an altered hormonal status we have compared the immunoreactive content of indole-3-acetic acid, cytokinins, abscisic acid, gibberellin and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) of seedlings and different tissues of P35S-rolA transgenic plants, transgenic plants expressing the rolA gene under control of its own phloem-specific promoter and wild-type plants. Multiple tissue-specific alterations of phytohormone concentrations are the consequence of rolA gene activity. Changes of phytohormonal content can explain part of the rolA-induced phenotypic alterations. Most strikingly, in young and fully developed leaves of rolA and P35S-rolA transgenic clones a 40–60% reduction of immunoreactive gibberellin A1 was found, as compared to wild-type leaves. Treatment of wild-type tobacco plants with inhibitors of gibberellin biosynthesis phenotypic alterations similar to those of rolA transgenic plants. This suggests that the reduction of gibberellic acid content is indirectly but causally involved in rolA-induced alterations of stem elongation and planar leaf blade growth.

72 citations


Journal ArticleDOI
TL;DR: An in vitro regeneration protocol was developed in chilli from immature zygotic embryos via direct somatic embryogenesis without involving intermediate callus and showed cytological and morphological uniformity.

69 citations


Journal ArticleDOI
TL;DR: It was shown that sprays of dilute sulphuric acid favoured grain germination by acting on the outer layers of the grain, and gibberellic acid was shown to exert its germination-stimulating effects and sodium hydroxide its inhibitory effects on the internal tissues.
Abstract: The germination of grains that had been steeped in solutions/suspensions of antibiotics was improved relative to water-steeped controls. The effect of the antibiotics was most striking for dormant grain that had been steeped for 90 min rather than 60 min. By incubating decorticated grains under different amounts of water it was shown that restriction of air to decorticated dormant grains reduced germination much more than was the case with decorticated, mature grains. Incubating the dishes of grain in oxygen, rather than air, overcame the inhibitory effect of excess water, confirming that it was the restriction of the oxygen supply by the water that checked germination. It was shown that sprays of dilute sulphuric acid favoured grain germination by acting on the outer layers of the grain. When acid-sprayed and untreated samples were decorticated and incubated their germination rates under different test conditions were essentially identical. In contrast gibberellic acid was shown to exert its germination-stimulating effects and sodium hydroxide its inhibitory effects on the internal tissues. By comparing the respiration rates of ground samples of grain (entire and decorticated; untreated and surface-sterilised) it was shown that microbes in the surface layers have substantial oxygen uptake rates. It seems that the competition of these microbes with the grain tissues for oxygen is a major cause of dormancy.

49 citations


Journal ArticleDOI
TL;DR: This paper reported identification of a 2189 bp cDNA clone from barley corresponding to a single-copy gene, Beg1 (Barley embryo globulin), on chromosome 4, which encodes a storage globulin.
Abstract: We report identification of a 2189 bp cDNA clone from barley corresponding to a single-copy gene, Beg1 (Barley embryo globulin), on chromosome 4, which encodes a storage globulin In barley, the major protein reserve in the aleurone layer belongs to the 7S globulin class of proteins found in many seeds Electrophoretically and antigenically similar proteins are present in the barley embryo Accumulation of Beg1 mRNA was noted beginning 15-20 days post-anthesis in both the aleurone layer and embryo of the developing barley grain but not in the starchy endosperm A high level of Beg1 mRNA is also present in the mature imbibed aleurones, which can be repressed by treatment with gibberellic acid This repressive effect of gibberellin on the levels of Beg1 mRNA is confirmed in the gibberellin response-constitutive mutant, slender, whose aleurone layers do not accumulate Beg1 mRNA even in the absence of applied gibberellic acid The deduced primary translation product of the Beg1 mRNA is a 637 amino acid (72 kDa) protein with homology to maize embryo globulin 1 (GLB1) and a partial sequence of a wheat 7S globulin The internal amino acid sequence of BEG1 closely matches the N-terminal sequence of isolated barley aleurone globulin Seven imperfect tandem repeats of 16 amino acids each are present near the N-terminus of BEG1, which conform to the consensus HGEGEREEEXGRGRGR, and contribute to the observed unusual amino acid composition of this protein A second, distinct barley globulin gene, Beg2, which is homologous to maize Glb2, was detected by Northern and Southern analysis Beg2 and Beg1 are regulated differently which may indicate variation in storage or utilization properties among the barley globulins

46 citations


Journal ArticleDOI
TL;DR: Embryos and aleurone layers from dormant grains responded stronger to ABA than those from nondormant grains and counteracted the ABA-induced inhibition of embryo germination.
Abstract: Dormant and nondormant isogenic barley grains were obtained by maturing grains under short day (SD) or long day (LD) growth conditions, respectively. Hormonal responses of isolated embryos and aleurone layers from these grains were studied. Addition of abscisic acid (ABA) reduced germination rate and percentage of embryos, and induced Rab (ABA-responsive) mRNA in aleurone layers from both types of grain. Embryos and aleurone layers from dormant grains responded stronger to ABA than those from nondormant grains. Gibberellic acid (GA 3 ) increased the germination rate and percentage of embryos from dormant grains and counteracted the ABA-induced inhibition of embryo germination

Journal ArticleDOI
TL;DR: The reported effects of these substances on in vitro behaviour will be of value in improving the frequency and uniformity of somatic embryo maturation, and therefore regeneration, in maize.

Journal ArticleDOI
TL;DR: The xyloglucan fragment was found to inhibit gibberellic acid-induced elongation of etiolated pea epicotyls with maximum inhibition at concentrations ranging from 10 -11 to 10 -9 M.
Abstract: The biological activity of a cell wall-derived xyloglucan nonasaccharide (XG9) was investigated using a bioassay with entire pea epicotyls (Pisum sativum cv. Progress). The xyloglucan fragment was found to inhibit gibberellic acid-induced elongation of etiolated pea epicotyls with maximum inhibition at concentrations ranging from 10 -11 to 10 -9 M. Growth of etiolated epicotyls in the absence of exogenously applied GA 3 was also inhibited by XG9 in the same concentration range

Journal ArticleDOI
TL;DR: Seed pretreatment with GA3 or kinetin nullified the deleterious effects imposed by irrigation with sea water particularly the high level on photosynthetic14CO2 fixation and inhibited leaf growth by themselves in almost all measurements.
Abstract: The antagonistic effects of some growth regulators [i.e. indol-3-yl-acetic acid (IAA), gibberellic acid (GA3) or kinetin] on stress imposed by sea water on leaf area, pigment and photosynthetic activity in leaves of broad bean plants at different stages of development were investigated. Seed priming with GA3 alleviated either partially or completely the effects induced by the two levels of sea water (10 and 25 %) used on leaf area at all experimental stages. However, IAA, GA3 and kinetin inhibited leaf growth by themselves in almost all measurements. Seed pretreatment with kinetin alleviated the inhibition of pigment production in sea water-irrigated plants. Furthermore, GA3 or kinetin nullified the deleterious effects imposed by irrigation with sea water particularly the high level (25 %) on photosynthetic14CO2 fixation.

Journal ArticleDOI
TL;DR: A sunflower genotype able to regenerate plants from in vitro cultures was identified by screening hybrids and inbred lines and factors affecting the frequency of embryo formation and plant regeneration are discussed.
Abstract: A sunflower genotype (Helianthus annuus L. cv. Florom-328) able to regenerate plants from in vitro cultures was identified by screening hybrids and inbred lines. Protoplasts of this genotype were isolated from dark grown hypocotyls and were cultured in droplets of agarose-solidified V-KM medium covered by liquid V-KM supplemented with naphthaleneacetic acid (NAA) and benzylaminopurine (BAP). One week later colonies were subjected to 2,4-dichlorophenoxyaceticacid for a one week period. Further culture in V-KM with reduced concentrations of NAA and BAP resulted in the appearence of somatic embryos. Maturation of embryos was achieved by culture on MS medium supplemented with NAA, BAP, gibberellic acid A3 and the ethylene inhibitor AgNO3. Embryos were then transferred onto hormone free MS medium for germination. The frequency of shoot formation in the best case was 9.6 percent of viable colonies (1.3 percent of protoplasts plated). Some of the shoots with roots could be transplanted into soil, others were grafted on hypocotyls of in vivo germinated seedlings. Eighty percent of grafted shoots and over 95 percent of rooted shoots survived. The plants flowered and produced 5 to 10 seeds each. Factors affecting the frequency of embryo formation and plant regeneration are discussed.

Journal ArticleDOI
TL;DR: The results suggest that GA-induced enhancement of sugar accumulation in the subhook cells is dependent on increased invertase activity, and the sugar accumulated in theSubhook may be involved in growth promotion by GA.
Abstract: The possible involvement of invertase in the action of gibberellic acid (GA) on stimulating sugar accumulation in growing subhooks of Alaska pea (Pisum sativum L. cv. Alaska) was studied. GA and indoleacetic acid (IAA) stimulated elongation growth to a similar extent. GA, in contrast to IAA, increased the amount of soluble sugars in the subhook. GA substantially increased invertase activity whereas IAA did not. These results suggest that the mode of action of GA and IAA differs, although both stimulate pea subhook growth. Cycloheximide (CH) inhibited the effect of GA on invertase activity, accumulation of soluble sugars, and elongation growth. Good correlations were found between invertase activity, the amount of soluble sugars and growth. The results suggest that GA-induced enhancement of sugar accumulation in the subhook cells is dependent on increased invertase activity. The sugar accumulated in the subhook may be involved in growth promotion by GA.

Journal ArticleDOI
TL;DR: This is the first report of plant regeneration from nucellar explants of A. marmelos through organogenesis from fertilized ovules of immature fruits of Aegle marmelo Corr.
Abstract: A protocol for organogenesis from nucellar explants excised from fertilized ovules of immature fruits of Aegle marmelos Corr. was developed. Adventitious buds were initiated on Murashige and Skoog's (MS) medium containing various combinations of 6-benzyladenine (BA), α-naphthalene-acetic acid (NAA), 3-indoleacetic acid and gibberellic acid. Medium containing 4.4 μm BA and 2.7 μM NAA produced the maximum number of adventitious buds per explant. Shoots were elongated by transferring explants with shoot buds to medium with a low concentration of BA (0.44 μM). Rooting of in vitro-regenerated shoots was obtained in half-strength MS medium with 4.9 μM indole-3-butyric acid. This is the first report of plant regeneration from nucellar explants of A. marmelos.

Journal ArticleDOI
TL;DR: A system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established and about 60% of plantlets survived after transplanting in pots.
Abstract: A system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established. Callus was induced on solid media supplemented with 8.5–15.0 mg.l−1 of indole-3-acetic acid and 3.46–34.64 mg.l−1 gibberellic acid. Callus was then subcultured on different media (solid or liquid) with or without IAA, or continuously maintained on the initiating media. Somatic embryos were obtained in subcultures on IAA-containing media as well as in long-term cultures on initiating media. The best results were achieved in liquid subcultures. About 60% of plantlets survived after transplanting in pots.

Journal ArticleDOI
TL;DR: The effect of a haulm application of gibberellic acid (GA) on the dormancy of seed potatoes harvested immature was investigated and several storage temperature regimes were imposed to examine the interaction between GA and storage temperature.
Abstract: In three experiments with cvs Diamant (short dormancy) and Desiree (long dormancy), the effect of a haulm application of gibberellic acid (GA) on the dormancy of seed potatoes harvested immature was investigated. Several storage temperature regimes were imposed to examine the interaction between GA and storage temperature. The storage regimes included 18 and 28 C continuously, hot pre-treatments of different duration (different periods at 28 C and subsequently 18 C) and a cold pre-treatment (20 days at 2 C and subsequently 18 C).

Journal ArticleDOI
TL;DR: Mussel processing wastes are transformed into a substrate suitable for diverse bioproductions, one being gibberellic acid, whose production is known to be closely related to the level of N in the culture medium, and various aspects of the relationships between the types of nutrients and their balances were studied.

Journal ArticleDOI
TL;DR: It is concluded that the dormancy mechanism is located in the scutellum, that it could be broken surgically or chemically by applying fusicoccin, and that dormancy could be restored by abscisic acid but not the latter.
Abstract: 2) the influence ofthree growth-regulating substances: gibberellic acid, fusicoccin, and abscisic acid The site of the mechanism was determined by assessing the germinability of surgically altered dormant seeds Effects of the growth substances were determined by assessing the germinability of seeds incubated in their presence Results revealed that dormancy could be broken surgically by altering the scutellum or chemically by applying fusicoccin Dormancy could be restored by abscisic acid in the former case but not the latter It is concluded that the dormancy mechanism is located in the scutellum, that it

Journal ArticleDOI
TL;DR: The results indicate that leaf yellowing is controlled by endogenous gibberellins and that the effect of phytochrome is mediated by gibBerellin synthesis.
Abstract: Chlorophyll loss in the leaves of cut flowering branches of Alstroemeria pelegrina L. cv. Stajello, placed in water in darkness at 20°, was inhibited by irradiation with red light and by the inclusion of gibberellic acid (GA3) in the water. The effects of red light were abolished when it was followed by far-red light. Effects of GA3 and red light were additive over a range of GA3 concentrations (0. 01–1 μM). Chlorophyll breakdown was increased by the inclusion of AMO-1618, ancymidol, or tetcyclasis in the water. The effect of these inhibitors of gibberellin synthesis was fully reversed by GA3. The inhibition of chlorophyll breakdown by red light was absent when AMO-1618, ancymidol or tetcyclasis were included in the water. The results indicate that leaf yellowing is controlled by endogenous gibberellins and that the effect of phytochrome is mediated by gibberellin synthesis.

Journal ArticleDOI
TL;DR: Gibberellic acid (GA3) was also applied in field trials and both GA3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests, where GA3 promoted vegetative growth at the expense of reproductive commitment.
Abstract: Endogenous gibberellins (GAs) were extracted from safflower (Carthamus tinctorius L.) stems and detected by capillary gas chromatography-mass spectrometry from which GA1, GA3, GA19,, GA20, GA29, and probably, GA44 were detected. The detection of these GAs suggests that the early 13-OH biosynthetic pathway is prevalent in safflower shoots. Deuterated GAs were used as internal standards and GA concentrations were determined in stems harvested at weekly intervals. GA1 and GA19 levels per stem increased but concentrations per gram dry weight decreased over time. GA20 was only detected in young stem tissue. Gibberellic acid (GA3) was also applied in field trials and both GA3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests. GA3 increased epidermal cell size, internode length, and increased internode cell number causing stem elongation. Conversely, paclobutrazol reduced stem height, internode and cell size, cell number and overall shoot weight. In field tests, GA3 increased total stem weight, but decreased leaf weight, flower bud number and seed yield. Thus, GA3 promoted vegetative growth at the expense of reproductive commitment. These studies collectively indicate a promotory role of GAs in the control of shoot growth in safflower, and are generally consistent with gibberellin studies of related crop plants.

Journal ArticleDOI
TL;DR: Results indicate that modification of gibberellin status can have a strong impact on the number of shoots formed in Albizzia julibrissin when placed on Gamborg's B5 medium supplemented with various levels of paclobutrazol, uniconazole, prohexadione calcium, or GA3.
Abstract: Hypocotyl explants of Albizzia julibrissin were placed on Gamborg's B5 medium supplemented with various levels of paclobutrazol, uniconazole, prohexadione calcium, or GA3. Callus formation was evident within one week after placement of the explants on the culture media. Green nodule-like structures protruded from the distal end of the explants within 10 days and developed into shoots within a month. These shoots readily formed adventitious roots when placed on fresh culture medium. All three of the gibberellin biosynthesis inhibitors increased shoot formation compared to the control. The number of shoots per explants was increased 107, 79, and 168% by 0.3–0.4 μM paclobutrazol, uniconazole, and prohexadione calcium, respectively. In contrast to the gibberellin biosynthesis inhibitors, GA3 decreased shoot formation. These results indicate that modification of gibberellin status can have a strong impact on the number of shoots formed.

Journal ArticleDOI
TL;DR: It is shown here that apices from older plants grown under high irradiance can undergo inflorescence differentiation in vitro after one LD even in the absence of GA3, as can apicesFrom plants in SD if GA3 is present in the medium, and appears to be necessary for differentiation beyond the spikelet primordia stage.
Abstract: Previous experiments have shown that shoot apices excised from plants of L. temulentum that had been exposed to one long day (LD) could form inflorescence primordia in vitro if gibberellic acid (GA3) was present in the medium whereas apices from plants in short days (SD) could not. We show here that apices from older plants grown under high irradiance can undergo inflorescence differentiation in vitro after one LD even in the absence of GA3, as can apices from plants in SD if GA3 is present in the medium. For apices excised from both SD and one LD plants, the order of effectiveness of gibberellins for inflorescence induction was 2,2-dimethyl GA4 > GA5 > GA3 > GA1, in agreement with their ranking for effectiveness on intact plants. Application of GA3 to leaves before apex excision can substitute for GA3 in the growth medium. The presence of GA3 in the medium is not required until 4-6 days after excision from plants given one LD, and appears to be necessary for differentiation beyond the spikelet primordia stage. Three hypotheses concerning the relation between GAs and the LD stimulus to flowering, as affected by plant age, are considered.

Journal ArticleDOI
TL;DR: Analysis of the GA3 dose-response curve of the secretory enzyme α-amylase and glyoxysomal enzyme isocitrate lyase demonstrated that a reduction in medium pH from 6.0 to 3.7 enhanced theGA3-response of isolated barley (Hordeum vulgare L.) aleurone layers.

Journal ArticleDOI
TL;DR: Histological studies revealed the origin of buds from calluses via organogenesis through organogenesis in Phaseolus coccineus L, which has maintained their ability to regenerate plants for more than two years.
Abstract: A method for long-term plant regeneration of Phaseolus coccineus L, is described. Shoot-tips and cotyledonary nodes cultured on a Murashige and Skoog medium supplemented with N6-benzylaminopurine, 10 μM, and α-naphthaleneacetic acid, 1μM, formed multiple bud-shoots. These shoots were transferred to medium containing BAP 1 μM, NAA 0.1 μM, and gibberellic acid 3 μM to promote shoot growth and further shoot multiplication. Rooting was achieved in medium with 11 μM indole-3-acetic acid. Rooted plants grew to maturity and were fertile. Cultures have maintained their ability to regenerate plants for more than two years. A sample of 30 regenerated plants (R0) was tested for chromosome number, all of them being diploid; seven isozymatic systems were electrophpretically analyzed in 82 R0 regenerated plants. No differences were observed in their electrophoretic patterns in comparison with those shown by seedlings. Histological studies revealed the origin of buds from calluses via organogenesis.

Journal Article
TL;DR: Plasmalemma from spinach leaves, a long day plant, has been isolated and characterized by biochemical markers and it appeared that the auxin activated the ATP-dependent accumulation of proton in plasma membrane vesicles.

Journal ArticleDOI
TL;DR: It is concluded that microbial activity on the surface layers of the grain, ‘maturity’ of the aleurone layer (enhanced by warm storage) and the duration of the steeping period all influence the responsiveness of barley aleur one layers to a dose of gibberellic acid.
Abstract: After steeping, with and without antimicrobial agents in the steep liquor, for 20 h or 60 h, barley grains were degermed. α-Amylase, produced in response to a fixed dose of gibberellic acid applied to the scutellar recess, was estimated at intervals during a subsequent incubation period. When samples with similar steeping periods were compared it was seen that enzyme production was greater in those that had been steeped in the presence of antimicrobial agents. This was particularly clear in samples that had been steeped for 60 h. Furthermore, grain which had been steeped for 60 h before de-embryonation produced more α-amylase, in response to gibberellic acid, than grain which had received a 20 h steep. Sub-samples of three lots of grain were warm-stored to overcome water sensitivity. When such grains were steeped, degermed and dosed with gibberellic acid they tended to produce more a-amylase than samples of control, cool-stored grain of the same original lots similarly treated and incubated. It is concluded that microbial activity on the surface layers of the grain, ‘maturity’ of the aleurone layer (enhanced by warm storage) and the duration of the steeping period all influence the responsiveness of barley aleurone layers to a dose of gibberellic acid.

Journal ArticleDOI
TL;DR: In this article, it has been proposed that gibberellic acid (GA3) promotes germination by overcoming restrictions in sugar production and utilization in afterripening-responsive dormant caryopses.
Abstract: It has been proposed that gibberellic acid (GA3) promotes germination by overcoming restrictions in sugar production and utilization in afterripening-responsive dormant caryopses. While their germination rates were similar, germination commenced sooner in afterripened wild oat (Avena fatua L.) caryopses than in dormant caryopses treated with GA3 and dormant excised embryos treated with GA3 plus fructose (Fru). Limited germination occurred in dormant excised embryos cultured with GA3 alone. Carbohydrate concentrations were measured over time in dormant caryopses and excised embryos whose germination was induced with GA3 and GA3 plus Fru. The concentration of sucrose (Suc) in the endosperm declined prior to germination of dormant GA3-treated caryopses. Raffinose (Raf) family oligosaccharides in the embryos of dormant GA-treated caryopses remained relatively constant prior to and shortly after the onset of germination. In contrast, Raf family oligosaccharides in the embryos of afterripened caryopses declined prior to germination. Together this suggests Raf family oligosaccharide utilization is not associated with germination per se. Increased starch levels, which occurred in dormant excised embryos treated with Fru and GA3 plus Fru, were associated with dormancy because similar effects were not apparent in afterripened embryos cultured with Fru. An initial decline in the concentration of Raf family oligosaccharides in dormant embryos cultured with GA3 or GA3 plus Fru seems to be a result of the excision process. GA3 appears to stimulate the germination of dormant embryos by enhancing the uptake or utilization of Fru. It appears that GA3 and afterripening-induced changes in carbohydrate utilization in dormant caryopses are different.