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Showing papers on "Gibberellic acid published in 1998"


Journal ArticleDOI
01 Oct 1998-Ecology
TL;DR: It is reported that smoke induces germination in 25 chaparral species, none of which were families known for heat-shock-stimulated germination, and it is suggested that such differences in response may affect postfire community structure.
Abstract: The California chaparral community has a rich flora of species with different mechanisms for cuing germination to postfire conditions. Heat shock triggers germination of certain species but has no stimulatory effect on a great many other postfire species that are chemically stimulated by combustion products. Previous reports have shown that charred wood will induce germination, and here we report that smoke also induces germination in these same species. Smoke is highly effective, often inducing 100% germination in deeply dormant seed populations with 0% control germination. Smoke induces germination both directly and indirectly by aqueous or gaseous transfer from soil to seeds. Neither nitrate nor ammonium ions were effective in stimulating germination of smoke-stimulated species, nor were most of the quantitatively important gases generated by biomass smoke. Nitrogen dioxide, however, was very effective at inducing germination in Caulanthus heterophyllus (Brassicaceae), Emmenanthe penduliflora (Hydrophyllaceae), Phacelia grandiflora (Hy- drophyllaceae), and Silene multinervia (Caryophyllaceae). Three species, Dendromecon rigida (Papaveraceae), Dicentra chrysantha, and Trichostema lanatum(Lamiaceae), failed to germinate unless smoke treatment was coupled with prior treatment of 1 yr soil storage. Smoke-stimulated germination was found in 25 chaparral species, representing 11 fam- ilies, none of which were families known for heat-shock-stimulated germination. Seeds of smoke-stimulated species have many analogous characteristics that separate them from most heat-shock-stimulated seeds, including: (1) outer seed coats that are highly textured, (2) a poorly developed outer cuticle, (3) absence of a dense palisade tissue in the seed coat, and (4) a subdermal membrane that is semipermeable, allowing water passage but blocking entry of large (molecular mass . 500) solutes. Tentative evidence suggests that permeability characteristics of this subdermal layer are altered by smoke. While the mech- anism behind smoke-induced germination is not known, it appears that smoke may be involved in overcoming different blocks to germination in different species. For example, in Emmenanthe penduliflora, NO2 in smoke was sufficient to induce germination, and most forms of physical or chemical scarification also induced germination. ForRomneya coulteri, NO2 alone failed to induce germination, and scarified seeds required addition of gibberellic acid. In Dicentra chrysantha, none of these treatments, nor smoke alone, induced germi- nation, but germination was triggered by a combination of soil burial followed by smoke treatment. Smoke-stimulated species differed substantially in the duration of smoke ex- posure required to induce germination, and this was inversely correlated with tolerance to smoke exposure. We suggest that such differences in response may affect postfire community structure.

287 citations


Journal ArticleDOI
TL;DR: Red light promotes GA1 synthesis in lettuce seeds by inducing Ls3h1 expression via phytochrome action, and this effect was canceled by a subsequent far-red-light treatment.
Abstract: Germination of lettuce (Lactuca sativa L.) seed is regulated by phytochrome. The requirement for red light is circumvented by the application of gibberellin (GA). We have previously shown that the endogenous content of GA1, the main bioactive GA in lettuce seeds, increases after red-light treatment. To clarify which step of GA1 synthesis is regulated by phytochrome, cDNAs encoding GA 20-oxidases (Ls20ox1 and Ls20ox2, for L. sativa GA 20-oxidase) and 3beta-hydroxylases (Ls3h1 and Ls3h2 for L. sativa GA 3beta-hydroxylase) were isolated from lettuce seeds by reverse-transcription polymerase chain reaction. Functional analysis of recombinant proteins expressed in Escherichia coli confirmed that the Ls20ox and Ls3h encode GA 20-oxidases and 3beta-hydroxylases, respectively. Northern-blot analysis showed that Ls3h1 expression was dramatically induced by red-light treatment within 2 h, and that this effect was canceled by a subsequent far-red-light treatment. Ls3h2 mRNA was not detected in seeds that had been allowed to imbibe under any light conditions. Expression of the two Ls20ox genes was induced by initial imbibition alone in the dark. The level of Ls20ox2 mRNA decreased after the red-light treatment, whereas that of Ls20ox1 was unaffected by light. These results suggest that red light promotes GA1 synthesis in lettuce seeds by inducing Ls3h1 expression via phytochrome action.

225 citations


Journal ArticleDOI
TL;DR: Although callus-free multiple-shoot formation was a function of cytokinin activity alone, faster bud break coupled with an enhanced frequency of shoot development and internode elongation were dependent on the synergistic influence of gibberellic acid (GA3) along with BA when used at an optimal concentration.
Abstract: A protocol is described for rapid and large-scale propagation of the woody aromatic and medicinal shrub Vitex negundo by in vitro culture of nodal segments from mature plants. Of the three different cytokinins – N6-benzyladenine (BA), kinetin, and thidiazuron – evaluated as supplements to Murashige and Skoog (MS) medium, BA at an optimal concentration of 2.0 mg/l was most effective in inducing bud break. Although callus-free multiple-shoot formation was a function of cytokinin activity alone, faster bud break coupled with an enhanced frequency of shoot development (92%) and internode elongation were dependent on the synergistic influence of gibberellic acid (GA3) when used at an optimal concentration (0.4 mg/l) along with BA (2.0 mg/l). The frequency of shoot proliferation was markedly influenced by the explanting season. By repeated subculturing of nodal segments harvested from the in vitro-formed axenic shoots on MS containing 1.0 mg/l BA and 0.4 mg/l GA3, prolific shoot cultures free from proximal callusing and showing a high-frequency multiplication rate were established. The percentage shoot multiplication (98–100%) as well as the number of shoots per node (six to eight) were highest during the first three culture passages, after which there was a gradual decline in shoot development. Rooting was best induced (94%) in shoots excised from proliferated shoot cultures on half-strength MS medium augmented with an optimal combination of indole-3-acetic acid and indole-3-butyric acid each at 1.0 mg/l. Vermi-compost was the most suitable planting substrate for hardening inside a plant growth chamber and its use ensured high-frequency survival (93%) of regenerated plants prior to outdoor transfer. Micropropagated plants established in garden soil were uniform and identical to the donor plant with respect to growth characteristics as well as vegetative and floral morphology.

149 citations


Journal ArticleDOI
TL;DR: Thidiazuron either alone or in combination with IAA induced high frequency shoot regeneration from primary leaf segments of three pigeonpea cultivars and Histological studies confirmed the mode of regeneration as shoot organogenesis.
Abstract: Thidiazuron either alone or in combination with IAA induced high frequency shoot regeneration from primary leaf segments of three pigeonpea cultivars Transfer of the cultures to medium with reduced concentration of thidiazuron resulted in further development of the shoots The regenerated shoots were subsequently transferred to medium supplemented with BA, IAA and gibberellic acid where 5-10% of the shoots elongated further Rooting of shoots could be obtained on half strength MS medium supplemented with NAA Histological studies confirmed the mode of regeneration as shoot organogenesis

87 citations


Journal ArticleDOI
TL;DR: GA3 was more effective than kinetin in enhancing the reduced germination and seedling growth of chickpea seeds along with amylase activity in cotyledons under NaCl induced saline conditions and IAA further inhibited both theGermination and growth of stressed seedlings.
Abstract: The percentage germination of chickpea seeds (Cicer arietinum L.cv. PBG-1) gradually decreased with increasing concentration of NaCl in the growth medium and was completely inhibited with 200 mM NaCl. In the presence of 75 mM NaCl, only 51% of the seeds germinated. Gibberellic acid (GA3) and kinetin at 6 µM concentration induced the maximum increase in % germination and seedling growth under salt stress. However, IAA further inhibited both the germination and growth of stressed seedlings. The reduction in amylase activity in cotyledons of stressed seedlings was partially reversed with GA3 and kinetin whereas IAA did not show any positive effect. GA3 was more effective than kinetin in enhancing the reduced germination and seedling growth of chickpea seeds along with amylase activity in cotyledons under NaCl induced saline conditions. The reduced uptake of radiolabelled 14C sucrose by cotyledons and its reduced distribution in the shoots and roots of stressed seedlings was increased with addition of GA3 in the medium. Cotyledonary amylase was separated into amylase 1 and amylase 2 by sephadex G 150 column chromatography. The reduced activities of both amylase 1 and amylase 2 in cotyledons under salt stress was returned to near normal levels with GA3 and there was also an increase in starch utilization, resulting in its lower concentration in cotyledons of GA3-supplemented stressed cotyledons.

86 citations


Journal ArticleDOI
TL;DR: Addition of gibberellic acid (GA3) and kinetin to medium containing 10% PEG increased the germination and seedling growth and the effect was maximum with 6 µM GA3 which was a better inducer of growth and germination under reduced water potential than Kinetin.
Abstract: The percent germination and seedling growth of chickpea (Cicer arietinum L. cv. PBG-1) decreased with increasing concentrations of exogenous polyethylene glycol 6000 (PEG). With 15% PEG in the growth medium germination was only 33% while with 10% PEG it was 58% as compared to 93% in control. Addition of gibberellic acid (GA3) and kinetin to medium containing 10% PEG increased the germination and seedling growth and the effect was maximum with 6 µM GA3 which was a better inducer of growth and germination under reduced water potential than kinetin. However, indole acetic acid (IAA) inhibited germination and growth of stressed seedlings. The activity of amylase in cotyledons under stress was significantly increased with GA3 while kinetin and IAA were less effective. Gibberellic acid also enhanced the mobilization of starch from cotyledons of stressed seedlings resulting in low starch levels in cotyledons compared with stressed seedlings.

81 citations


Journal ArticleDOI
TL;DR: The results suggest that in the presence of the agents belonging to class II, ABA responsiveness of isolated embryos from dormant grains is decreased, compared to nontreated embryos.
Abstract: The endogenous ABA contents of dormant and nondormant barley grains were determined following application of different compounds to break dormancy. The chemicals used for breaking of dormancy in intact dormant grains were weak and strong acids, alcohols,. hydrogen peroxide, cyanide, nitrate, salicylic acid, gibberellic acid and fusicoccin. The dormancy-breaking compounds could be classified into two major groups: compounds that caused a decrease in endogenous ABA (class I) and compounds which did not affect endogenous ABA (class II). Class I compounds included gibberellic acid, ethanol, hydrogen peroxide, nitrate, salicylic acid; class II compounds were fusicoccin, acid (H2SO4), sodium azide, n-caproic acid. in addition, these dormancy-breaking compounds were able to stimulate the germination rate when applied to embryos isolated from dormant grains. The concentrations necessary for stimulation of germination of isolated embryos were much lower than the concentrations for breaking the dormancy of intact grains. After embryos were isolated from dormant grains and incubated in water, ABA was determined in both embryos and in the incubation media. The class I compounds stated above also reduced ABA content in the incubation medium of isolated embryos, while class II compounds had no effect on ABA content of the medium. External application of ABA could overcome the effect of dormancy-breaking compounds of class I but not of class II. The results suggest that in the presence of the agents belonging to class II, ABA responsiveness of isolated embryos from dormant grains is decreased, compared to nontreated embryos.

80 citations


Journal ArticleDOI
18 May 1998-Planta
TL;DR: Findings indicate that GA enhances cell elongation by increasing wall extensibility, osmotic concentration being kept unchanged by starch degradation.
Abstract: The mechanism of gibberellin (GA)-induced leaf sheath growth was examined using a dwarf mutant of rice (Oryza sativa L. cv. Tan-ginbozu) treated in advance with an inhibitor of GA biosynthesis. Gibberellic acid (GA3) enhanced the growth of the second leaf sheath, but auxins did not. Measurement of the mitotic index and cell size revealed that cell elongation rather than cell division is promoted by GA3. Gibberellic acid increased the extensibility of cell walls in the elongation zone of the leaf sheath. It also increased the total amount of osmotic solutes including sugars in the leaf sheath, but did not increase the osmotic concentration of the cell sap, due to an accompanying increase in cell volume by water absorption. In the later stage of GA3-induced growth, starch granules completely disappeared from leaf sheath cells, whereas dense granules remained in control plants. These findings indicate that GA enhances cell elongation by increasing wall extensibility, osmotic concentration being kept unchanged by starch degradation.

76 citations


Journal Article
TL;DR: In this paper, the salinity induced dormancy of P. aviculare seeds was alleviated by GA. Seeds that did not germinate after 20 days were subjected to a 90-day stratification treatment.
Abstract: Germination of Polygonum aviculare L. seeds collected at a saline site near New England, Ohio was studied. Seeds that did not germinate after 20 days were subjected to a 90 day stratification treatment. Optimal germination percentages were obtained (about 100%) for stratified seeds in low and non-saline controls at the 5-15 °C thermoperiod. Increase in both salinity and temperature caused a decrease in both the percentage and rate of seed germination. Recovery of seed germination after twenty days of immersion in salt solution was complete at the low thermoperiod in high salinity treatments and it decreased with an increase in temperature. The salinity induced dormancy of P. aviculare seeds was alleviated by GA. Classification of germination recovery types from saline conditions was related to an interaction between salinity and temperature, and the need to study both of these factors simultaneously was confirmed in order to categorize a species response to salt stress.

75 citations


Journal ArticleDOI
01 Dec 1998-Planta
TL;DR: The results may indicate that salT expression in each region of the plant is dependent on the metabolic activity of the cells as well as on whether or not they are stressed.
Abstract: The expression pattern of the salT gene was analyzed in different cell types and organs of rice (Oryza sativa L.) in response to saline and hormonal treatments to obtain detailed information on the physiological cues controlling gene expression. Gel blot analysis of RNA and in-situ hybridization performed on seedlings grown for 10 ds in the presence of 1% NaCl revealed that salT was expressed mainly in the younger tissues of the plant. In contrast, 6-week-old plants exhibited maximal salT mRNA accumulation in sheaths of older leaves. In addition, salT was normally expressed in rapidly dividing suspension-cultured cells, but not in quiescent ones. Altogether, these results may indicate that salT expression in each region of the plant is dependent on the metabolic activity of the cells as well as on whether or not they are stressed. The effects of two growth regulators, abscisic acid (ABA) and gibberellic acid, were investigated in combination with the effects of NaCl. Gibberellic acid had a synergistic effect on the induction of the salT gene when combined with 0.5% NaCl, but did not induce salT on its own. At 10 μM, ABA induced salT both in the absence of NaCl and in its presence. Whereas 1 μM ABA acted additively with NaCl to induce gene expression, 5 μM ABA with NaCl was only as effective as NaCl alone. This may indicate that the two stimuli act independently and possibly through antagonistic signal transduction pathways.

71 citations


Journal ArticleDOI
TL;DR: In this article, the effectiveness of different bioregulators in enhancing bell pepper (Capsicum annuum L.) yield and fruit quality, the commercial biOREgulators CCC, NAA, GA 3, and Biozyme® were sprayed on plants at flower initiation, followed by two additional applications at 30-day intervals.
Abstract: To test the effectiveness of different bioregulators in enhancing bell pepper (Capsicum annuum L.) yield and fruit quality, the commercial bioregulators CCC, NAA, GA 3 ,and Biozyme® were sprayed on plants at flower initiation, followed by two additional applications at 30-day intervals. Biozyme produced a significant increase in total yield but 40% of the fruit were not marketable. Treatment with NAA produced the highest yield of marketable fruit. Treatments did not affect fruit firmness compared to the control. Gibberellic acid increased fruit ascorbic acid and citric acid concentrations and Biozyme, GA 3 , and CCC increased fruit soluble solids content. Biozyme treatment increased fruit fructose, sucrose, carotenoid, and lycopene concentration. Treatments had no effect on fruit calcium concentration or pH. Chemical names used: chlormequat chloride (CCC); naphthaleneacetic acid (NAA), gibberellic acid (GA 3 ); GA 3 + IAA (indole-3-acetic acid) + zeatine + micronutrients (Biozyme®).

Journal ArticleDOI
TL;DR: A cDNA encoding for a functional ornithine decarboxylase has been isolated from a cDNA library of carpels of tomato and it is shown to be up-regulated during early fruit growth induced by 2,4-dichlorophenoxyacetic acid and gibberellic acid.
Abstract: A cDNA encoding for a functional ornithine decarboxylase has been isolated from a cDNA library of carpels of tomato (Lycopersicon esculentum Mill.). Ornithine decarboxylase in tomato is represented by a single-copy gene that we show to be up-regulated during early fruit growth induced by 2,4-dichlorophenoxyacetic acid and gibberellic acid.

Journal ArticleDOI
TL;DR: The same petiole protoplast populations showed transient expression of the gusA gene introduced using electroporation, and mature plants appeared phenotypically normal.
Abstract: A method for regenerating plants from petiole protoplasts of the in vitro-raised sweet potato cultivar Jewel is described. Protoplast yields of 3.0–5.0×106 were obtained following 4–6 h digestion of 1- to 2-cm petioles (1 g fresh weight) with 1% Cellulase-R10, 2% Macerozyme-R10, and 0.3% Pectolyase Y-23 in a washing solution with 9% mannitol. A plating density of 105 protoplasts/ml was optimal for subsequent division. An initial division frequency of 12–15% was obtained in liquid or agarose-solidified KP8 culture medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) (0.9 μm), and zeatin (2.3 μm). Colonies consisting of 100–200 cells were formed after 4 weeks in the dark at 24±2°C. The frequency of colony formation was improved by the gradual addition of fresh liquid KP8 medium of lower osmoticum. Protocalli (1–2 mm in diameter) were formed after an additional 4–6 weeks under continuous illumination and regular dilution with fresh culture medium. Morphogenic callus formed globular and heart-shaped embryos that developed into cotyledon stage embryos, following transfer of calli onto medium containing 2,4-D (11.3 μm) and benzylaminopurine (2.2 μm). Subsequently, embryo conversion to plantlets was obtained on basal medium with 2% sucrose and 3.5 μm gibberellic acid. Regenerated plantlets were successfully transplanted in soil. Mature plants appeared phenotypically normal. The same petiole protoplast populations showed transient expression of the gusA gene introduced using electroporation.

Journal ArticleDOI
TL;DR: A method for regenerating pigeonpea [Cajanus cajan (L.) Millsp.] plants has been developed using distal cotyledonary segments of mature seeds as explants and may be useful for improving the crop through genetic manipulations.
Abstract: A method for regenerating pigeonpea [Cajanus cajan (L.) Millsp.] plants has been developed using distal cotyledonary segments of mature seeds as explants. A large number of shoot buds were induced directly from explants of genotypes T-15-15 and GAUT-82-90 when cultured on six different basal media fortified with 22.2 μm N6-benzylaminopurine, 2.3 μm kinetin, and 271 μm adenine sulfate. The shoot buds developed into shoots when they were subcultured on the same medium but with one-tenth concentrations of cytokinins and adenine sulfate. The shoots elongated by subculturing first two to three times on Murashige and Skoog (MS) basal medium supplemented with 2.22 μm N6-benzylaminopurine and 0.54 μmα-naphthaleneacetic acid or on half-strength MS medium containing 2.89 μm gibberellic acid, and then once on the same medium without growth regulators. Elongated shoots were rooted with 80–85% efficiency on MS medium with 4.92 μm indole-3-butyric acid and the plantlets were transferred for hardening. Plants survival in pots was 70–75%. This method may be useful for improving the crop through genetic manipulations.

Journal ArticleDOI
TL;DR: Plant growth regulators, gibberellic acid (GA) and kinetin, significantly alleviated the salinity-induced germination inhibition of both seed types but over different salinity ranges and to different degrees.
Abstract: Arthrocnemum indicum Willd., a stem succulent perennial in the family Chenopodiaceae, is widely distributed along the coastal areas of Pakistan and forms an important component of the vegetation of salt marshes in the vicinity of mangrove swamps. Seed germination of halophytes is often inhibited by hypersaline conditions at these sites, which prevents the establishment of new populations (Ungar 1991). We studied the affect of growth regulators and compatible osmotica in alleviating the innate and salinity-induced dormancy in dimorphic (brown and black) seeds of A. indicum. Germination of both types of seeds decreased with an increase in salinity. Brown seeds germinated at the highest salinity concentration (1000 mM), whereas only a few black seeds germinated at 800 mM NaCl, and no germination was recorded at 1000 mM NaCl. The osmotica, proline and betaine, did not relieve salinity-induced dormancy in either black or brown seeds. Plant growth regulators, gibberellic acid (GA) and kinetin, significantly (P ...

Journal ArticleDOI
TL;DR: The ability to form plants in vitro strongly increased with increasing embryo developmental stage and the frequencies of zygotic embryos ranged from 82 to 88%.
Abstract: Embryo development in vivo has been studied in four Citrus aurantium L. polyembryonic genotypes. Seeds were collected 65, 85, 105, 125 and 220 days after pollination (DAP). None of the immature seeds harvested 65 and 85 DAP contained visible embryos. A single embryo at a more advanced developmental stage was observed in the central position at the micropylar apex of the embryo sac in about 74% of seeds harvested at 105 DAP, while at 125 and 220 DAP the majority of seeds had two or more embryos at the same developmental stage crowded together. Restriction fragment length polymorphism (RFLP) analysis of low- and high-copy-number nuclear DNA was used to distinguish zygotic from nucellar seedlings. Analysis of plantlets derived from in vitro culture of the bigger embryos, located in the central position at the micropylar apex of the embryo sac of seeds harvested at 105 DAP, established that the frequencies of zygotic embryos ranged from 82 to 88%. Media for immature embryo germination in vitro were based on the nutrients and vitamins of Murashige and Skoog (MS) and Murashige and Tucker (MT) media supplemented with various concentrations of sucrose and growth regulators. A total of 76% of globular stage embryos (<0.3mm) germinated on MT medium containing 150 mM sucrose and 14.4 μM gibberellic acid. Heart stage embryos (0.3-0.8 mm) germinated at 95% on MT medium supplemented with 150 mM sucrose and 2.9 μM gibberellic acid. The addition of 500 mg/l malt extract to MS medium increased the germination of early cotyledon stage (0.8-2.0mm) embryos to 98%. The optimum sucrose concentration for embryo rescue was 150 mM for the three embryo developmental stages. The ability to form plants in vitro strongly increased with increasing embryo developmental stage.

Journal ArticleDOI
TL;DR: GA 3 and CO 2 could provide an effective means for maintaining fresh produce quality in parsley after postharvest senescence of parsley is studied.
Abstract: We studied the effect of CO 2 and gibberellic acid (GA 3 ) on postharvest senescence of parsley (Petroselinum crispum Mill.) and on ethylene induced senescence. GA 3 or CO 2 treatment retarded, with a similar efficiency, chlorophyll and protein degradation, amino acids accumulation and respiration rate. Treatment with GA 3 and CO 2 together resulted in an additive senescence retarding effect. The promoting effect of ethylene on senescence could be retarded with either CO 2 or GA 3 . Thus, GA 3 and CO 2 could provide an effective means for maintaining fresh produce quality in parsley.

Journal ArticleDOI
TL;DR: Somatic embryogenesis in American ginseng was investigated from three explant sources (root, leaf and epicotyl) with Murashige and Skoog medium containing different growth regulators, and somatic embryos developed on this medium with the highest frequency obtained after 3 mo. from seedling-leaf explants.
Abstract: Somatic embryogenesis in American ginseng (Panax quinquefolium L.) was investigated from three explant sources (root, leaf and epicotyl) with Murashige and Skoog (MS) medium containing different growth regulators. Mature roots and leaves obtained from 3- to 5-yr-old field-grown plants, and seedling leaves and epicotyls from plantlets grownin vitro, were evaluated. From root and epicotyl explants, callus development was optimal with 3,6-dichloro-o-anisic acid (dicamba) (9.0 μM) and kinetin (KN) (5.0 μM) as the growth regulators. When these calluses were transferred after 3 mo. to dicamba alone (9.0 μM), somatic embryo formation was observed at an average frequency of 15.6% in root explants after an additional 3 mo., and 2% in epicotyl explants after an additional 6 mo. No plantlets were recovered because the embryos germinated to form shoots with no roots. From leaf explants, callus growth was optimal with α-naphthaleneacetic acid (NAA) at 10.0 μM and 2,4-dichlorophenoxyacetic acid (2,4-D) at 9.0 μM. Somatic embryos developed on this medium, with the highest frequency (40%) obtained after 3 mo. from seedling-leaf explants. Calluses on mature leaves formed somatic embryos after 7 mo. with NAA/2,4-D at an average frequency of 30%. Transfer of these somatic embryos to 6-benzyladenine/gibberellic acid (4.4/2.9 μM) promoted shoot development but no roots were observed. Up to 100% of germination was observed within 6 wk on half-strength MS salts containing activated charcoal (1%) and on NAA/2,4-D (5.0/4.5 μM) with charcoal (1%). On the latter medium, somatic embryos enlarged and frequently gave rise to new somatic embryos after a brief callusing phase. The embryos germinated through a two-stage process, involving the elongation of the root followed by the formation of a shoot. The highest recovery of ginseng plantlets from germinated embryos was 61.0%. Following transfer to potting medium and maintenance under conditions of high humidity and low light intensity, the plantlets elongated and developed new leaves. A high percentage (50%) of these plants have been acclimatized to soil.

Journal ArticleDOI
TL;DR: Light-yellow, loose, glossy, globular callus was formed, and the highest frequency was 35.7%, and established plants survived following transfer to soil at a frequency of 71%.
Abstract: Mature zygotic embryos from three seed sources of loblolly pine were cultured on callus induction medium containing 10 mg l(-1) alpha-naphthaleneacetic acid, 4 mg l(-1) benzyladenine (BA), 400 mg l(-1) casein hydrolysate, and 400 mg l(-1) glutamine for 6 weeks. Light-yellow, loose, glossy, globular callus was formed, and the highest frequency was 35.7%. The highest differentiation frequency of callus on adventitious bud induction medium was 62.1%. After culture of calli with adventitious buds on elongation medium for 6 weeks, adventitious shoots more than 1.0 cm in height were selected for rooting. On rooting medium supplemented with 0.1 mg l(-1) indole-3-butyric acid, 1 mg l(-1) BA, and 0.5 mg l(-1) gibberellic acid, the highest rooting frequency of adventitious shoots was 46% in a culture period of 6 weeks. Established plants survived following transfer to soil at a frequency of 71%.

Journal ArticleDOI
TL;DR: The combination of dormancy and Genetic and physiological data indicate that gibberellic seed longevity allows viable wild oat seeds to infest acid does not have a primary role in the regulation of agricultural soils for several years, and GA may play a ancy in wild Oat.
Abstract: germinating soon after they fall to the soil (Naylor, 1983; Cavers et al., 1992). The combination of dormancy and Genetic and physiological data indicate that gibberellic seed longevity allows viable wild oat seeds to infest acid does not have a primary role in the regulation of agricultural soils for several years (Naylor, 1983). Better seed dormancy in wild oat (Avena fatua L.). The gibberel- understanding of seed dormancy may enhance integrated lic acid sensitivity threshold of dormant caryopses weed management strategies, allow the development of imbibed for 7 d was 1 mM. Intact dormant seeds were predictive seed germination models, and provide insights after-ripened for 0, 2, 4, 8, 12, 16, and 20 weeks at into developmental arrest in plants. 40°C and imbibed in H 2 0, 100 nM or 1 mM gibberellic A dormant wild oat seed fails to germinate under acid. The length of the after-ripening interval was conditions which normally favour germination, but afterinversely related to the mean base gibberellic acid con- ripening in warm and dry conditions releases the seed centration (the concentration resulting in 50% germina- from dormancy. Germination of dormant wild oats can tion). Thus, after-ripening, not gibberellic acid, is the be stimulated by treatment with exogenous gibberellic principal factor that regulates the release of seed dorm- acid (GA) (Adkins et al., 1986). Thus, GA may play a ancy in wild oat. F 2 caryopses (dormant◊non-dormant) role in releasing dormancy. However, there is no generally classified by germination response to progressively accepted hypothesis to explain the role of after-ripening higher gibberellic acid concentrations, were pooled or GA in the breaking of seed dormancy (Simpson, 1990). according to their gibberellic acid requirement: low, Our hypothesis is that after-ripening regulates genes or medium and high. Germination responses of the F 3 pro- gene products that control the germination response of geny from the low, medium, and high gibberellic acid dormant wild oat seeds and the activities of these factors requirement pools were regressed on to the F 2 parent are largely independent of GA. The overall objective was values, and a heritability for germination response to to characterize the role of GA in the dormancy of wild gibberellic acid, h2=0.24, was calculated. Random amp- oat seed. Specific objectives were to (1) establish the lified polymorphic DNA analysis of DNA samples from mean GA base concentrations for dormant and partially F 2 pools requiring low and high gibberellic acid concen- after-ripened caryopses, (2) determine if there is genetic trations were screened with 200 decamer primers and evidence for the role of GA in releasing dormancy, and no polymorphisms were found. The findings of this (3) screen for polymorphic DNA markers between F

Journal ArticleDOI
TL;DR: Gibberellic acid (GA 3 ) treatments (30 and 60 μg litre -1 ) were applied to young plants (Fragaria ananassa cv Chandler) to determine the effects of exogenous treatments of GA 3 on PAL and TAL activities as mentioned in this paper.
Abstract: Gibberellic acid (GA 3 ) treatments (30 and 60 μg litre -1 ) were applied to young plants (Fragaria ananassa cv Chandler). Fruits were harvested at various developmental stages (14, 21, 28 and 35 days from fruit set). Weight and size, phenolic compounds (total polyphenols and anthocyanins) and enzyme activities, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) were determined. Our aim was to obtain detailed information about PAL and TAL activities related to the strawberry colour during development and ripening processes and to determine the effects of exogenous treatments of GA 3 on PAL and TAL activities. Exogenous treatments of GA 3 improve weight, size and colour of strawberry fruits, and affect PAL and TAL activities. We found that the anthocyanin content and PAL activity are enhanced by the exogenous treatment of GA 3 in the range of 30 μg litre -1 . However, with the higher GA 3 treatment, only the anthocyanin content is affected in that way. These findings suggest that gibberellic acid effect on PAL, TAL and ultimately anthocyanin enhancement is dosage related and saturation of the response occurs at 30 μg litre -1 .

Journal ArticleDOI
TL;DR: Gibberellic acid antagonism of the growth inhibitory and stress protective effects of paclobutrazol was investigated in wheat seedlings and changes in protein expression were investigated in an attempt to understand the basis of P-induced stress protection.

Journal ArticleDOI
TL;DR: A very high reducing sugar content in the stem of GA3-treated crop indicated active hydrolysis of sucrose coming from the leaves, leading to its reduced supply to the tubers, but in the CCC treated crop, the higher chlorophyll content of the leaves with reduced stolon length will promote efficient sucrose supply toThe tubers.
Abstract: Treatment of potato plants with gibberellic acid (GA3) enhanced both shoot and stolon growth and dry weight but delayed tuber initiation and decreased tuber yield. Conversely, treatment with chlorocholine chloride (CCC) growth retardant reduced shoot and stolon growth and dry weight but promoted tuberisation. Chlorophyll a and b contents were both increased appreciably with CCC. In the tubers, CCC increased starch content by 11% compared to untreated control, whereas GA3 decreased starch content by about 13%. A very high reducing sugar content in the stem of GA3-treated crop indicated active hydrolysis of sucrose coming from the leaves, leading to its reduced supply to the tubers because of further possible sucrose hydrolysis while passing through the long stolons. However, in the CCC treated crop, the higher chlorophyll content of the leaves with reduced stolon length will promote efficient sucrose supply to the tubers. © 1998 Society of Chemical Industry.

Journal ArticleDOI
TL;DR: In this article, trials on the effectiveness of gibberellic acid (GA3) for controlling storage losses were carried out on the two main species of yam (D cayenensis rotundata and D alata) grown in the Ivory Coast.
Abstract: The annual vegetative cycle of the yam (Dioscorea spp) necessitates a long period of storage. Losses during this period are high and are mainly due to germination. Trials on the effectiveness of gibberellic acid (GA3) for controlling storage losses were carried out on the two main species of yam (D cayenensis rotundata and D alata) grown in the Ivory Coast. Methods of application at the apex adapted to the rural environment were tested. Treatment with GA3 prolonged the dormancy period and thus reduced losses. This substance was effective at low concentration with a long soaking duration (75 mg litre−1 for 2 h) and during a soaking of short duration with a higher concentration (0·5 h at 150 mg litre−1). Because of its stability at ambient temperature, the solution was still active 3 days after being prepared and after reuse of the same dip six times. © 1998 SCI.

Journal ArticleDOI
TL;DR: Seed exposure to GA 3 during rather than after prechilling was more effective in promoting Indiangrass establishment, and the effects on seedling emergence and growth of providing GA 3 at 1000 mg.L -1 during the 2-week prechills did not influence seedling shoot dry mass.
Abstract: Following dry storage for 5 or 11 months (new and old seeds, respectively) at 5 °C, less than 10% of the seeds of Indiangrass germinated as determined by a standard germination test. We attempted to increase germination by subjecting seeds to dormancy-breaking treatments, including sodium hypochlorite soak (5.25% v/v NaOCl; 20 or 60 min), prechilling (5 °C for 2 weeks), gibberellic acid during germination (GA 3 , 1000 mg.L -1 ), and combinations thereof. Treatment with NaOCl increased the germination of non-prechilled seeds only when they were germinated in GA 3 ; a 60-min soak in NaOCl increased germination to 53% and 65% in new and old seeds, respectively. Prechilling increased germination to 65% and 47% in new and old seeds, respectively. Germination of new, prechilled seeds was increased further to 86% by either a 20-min soak in NaOCl or germination in GA 3 , Germination of old, prechilled seeds was not promoted further by treatment with NaOCl, but was increased to 67% by germination in GA 3 ; Since NaOCl treatment alone failed to promote germination, we examined the effects on seedling emergence and growth of providing GA 3 at 1000 mg.L -1 during the 2-week prechilling period. While prechilling alone increased emergence to an average 34% for new and old seeds, prechilling with GA 3 increased emergence to 75% and 50% for new and old seeds, respectively. These treatments did not influence seedling shoot dry mass. Seed exposure to GA 3 during rather than after prechilling was more effective in promoting Indiangrass establishment.

Book ChapterDOI
01 Jan 1998
TL;DR: The identification and quantification of the plant growth hormones indoleacetic acid and gibberellic acid, produced by plant growth-promoting rhizobacteria (PGPR) was carried out by using high-pressure liquid chromatography (HPLC).
Abstract: Identification and quantification of the plant growth hormones indoleacetic acid and gibberellic acid, produced by plant growth-promoting rhizobacteria (PGPR), was carried out by using high-pressure liquid chromatography (HPLC). The PGPR strains were isolated from roots of rice, wheat and kallar grass and belonged to the genera Azoarcus, Azospirillum, Enterobacter, Pseudomonas and Zoogloea. For these studies, bacteria were grown in liquid nitrogen free malate (NFM) or combined carbon medium (CCM) containing tryptophan and combined nitrogen. Some Azospirillum strains produced both indoleacetic acid and gibberellic acid, while none of the Enterobacter spp. tested produced these growth hormones. Azoarcus strain K-1 produced higher amounts of gibberellic acid and Azospirillum strain ER-2 produced higher amounts of indoleacetic acid. Indoleacetic acid production increased with the age of bacterial cultures while a decrease in the production of gibberellic acid was noted at later growth stages. Pure indoleacetic acid and gibberellic acid in the concentration range 1–2 µg/ml increased root area and plant biomass of rice and wheat. Among PGPR strains tested, Pseudomonas 96–51 and its extract containing growth hormones increased root area, root length and plant biomass of rice and wheat.

Journal Article
TL;DR: Changes in the amount of endogenous phytohormones in flower buds located in different parts of the plant indicate that ABA in particular plays an important role in the formation of flowering order in saf- flower.
Abstract: Changes in the amounts of endogenous gibberellic acid (GA 3 ), indole-3-acedic acid (IAA) and abscisic acid (ABA) during different growth periods of the safflower were studied by high-perfor- mance liquid chromatography (HPLC). A correlation was confirmed between low levels of GA 3 , as well as high levels of ABA, and the initia- tion of flowering. IAA reached its maximum level during bud formation, indicating that IAA might play an active role in the differentiation of bud formation. Changes in the amount of endogenous phytohormones in flower buds located in different parts of the plant indicate that ABA in particular plays an important role in the formation of flowering order in saf- flower.

Journal ArticleDOI
TL;DR: In vitro culture conditions for plant regeneration of tef, Eragrostis tef (Zucc.) Trotter were established and neither chlorophyll-deficient plants nor morphological variants were found among regenerants.
Abstract: The study was carried out to establish in vitro culture conditions for plant regeneration of tef, Eragrostis tef (Zucc.) Trotter. Mature seeds of two Ethiopian varieties, DZ-01-354 and DZ-01-196, were used to initiate callus cultures on Murashige and Skoog (MS) medium with different auxins. Four- and 8-week-old calli induced on a medium with 2.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) were subcultured onto various media to induce somatic embryogenesis. Compact, nodulated, embryogenic callus was observed after transfer onto MS-callus proliferating (CP) medium. Embryogenic tissue appeared on soft and amorphous callus and developed into somatic embryos during a subsequent subculture to MS embryo-promoting (EP) media. Various growth regulator combinations were tested in CP and EP media to obtain a high efficiency of somatic embryo formation. The highest frequency of calli forming somatic embryos (56.1–68.3%) was observed when CP media with 2.0 or 4.0 mg/l 2,3,5-triiodobenzoic acid were employed and then cultures were transferred to EP media with 0.5 mg/l 2,4-D and 0.5 mg/l kinetin followed by 0.5 mg/l indole-3-acetic acid and 0.5 mg/l N6-benzyladenine. Plant development from somatic embryos was obtained on MS medium supplemented with 1.0 mg/l gibberellic acid. On average, 71.2% of calli displaying somatic embryos converted into plants. Regenerated plants were successfully transferred to soil. Neither chlorophyll-deficient plants nor morphological variants were found among regenerants. All regenerated plants were fertile.

Journal ArticleDOI
TL;DR: In addition to removing IAA transport from the apical shoot, the accumulation of a promotive factor is also necessary to induce parthenocarpic growth in decapitated plants.
Abstract: The role of the apical shoot as a source of inhibitors preventing fruit growth in the absence of a stimulus (e.g. pollination or application of gibberellic acid) has been investigated in pea (Pisum sativum L.). Plant decapitation stimulated parthenocarpic growth, even in derooted plants, and this effect was counteracted by the application of indole acetic acid (IAA) or abscisic acid (ABA) in agar blocks to the severed stump. The treatment of unpollinated ovaries with gibberellic acid blocked the effect of IAA or ABA applied to the stump. [3H]IAA and [3H]ABA applied to the stump were transported basipetally, and [3H]ABA but not [3H]IAA was also detected in unpollinated ovaries. The concentration of ABA in unpollinated ovaries increased significantly in the absence of a promotive stimulus. The application of IAA to the stump enhanced by 2- to 5-fold the concentration of ABA in the inhibited ovary, whereas the inhibition of IAA transport from the apical shoot by triiodobenzoic acid decreased the ovary content of ABA (to approximately one-half). Triiodobenzoic acid alone, however, was unable to stimulate ovary growth. Thus, in addition to removing IAA transport from the apical shoot, the accumulation of a promotive factor is also necessary to induce parthenocarpic growth in decapitated plants.

Journal ArticleDOI
TL;DR: GA3 application in vitro resulted in rapid accumulation of GDA-1 mRNA in LD-grown G2 pea apical buds, which is compatible with its delaying effect on apical senescence and shows that photoperiod may change the efficiency of gibberellin perception by plants.
Abstract: Using cDNA representational difference analysis (cDNA RDA), we isolated a cDNA named GDA-1 from a cDNA library constructed with mRNA from short-day (SD) grown G2 pea apical tissue The amino acid sequence deduced from GDA-1 shares partial identity with the B2 protein which is expressed during embryogenesis of carrot cells Northern analysis showed that GDA-1 mRNA is abundant in SD-grown G2 pea apical buds In long-day (LD) conditions, there was almost no detectable GDA-1 mRNA When LD-grown G2 peas were kept in continuous darkness for 24 h, the GDA-1 mRNA content reached a level equivalent to about 50% of that in the SD samples On the other hand, when SD-grown peas were transferred into the light for 24 h, the amount of hybridizable GDA-1 mRNA dropped to the same as that of LD-grown plants GDA-1 expression was found to be independent of flower initiation time GA3 application in vitro resulted in rapid accumulation of GDA-1 mRNA in LD-grown G2 pea apical buds, which is compatible with its delaying effect on apical senescence Time-course experiments revealed that GDA-1 is induced within 15 min of GA3 application Exogenous GA3 did not influence the expression of GDA-1 in SD-grown G2 peas Since both photoperiod and GA induce the expression of GDA-1, we speculate that they may activate similar signal transduction pathways in G2 peas Our work also shows that photoperiod may change the efficiency of gibberellin perception by plants