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Showing papers on "Gibberellic acid published in 2003"


Journal ArticleDOI
TL;DR: It was found that gibberellin and jasmonic acid had a synergistic effect on the induction of trichomes, suggesting important interactions between these two compounds.
Abstract: Leaf trichomes protect plants from attack by insect herbivores and are often induced following damage. Hormonal regulation of this plant induction response has not been previously studied. In a series of experiments, we addressed the effects of artificial damage, jasmonic acid, salicylic acid, and gibberellin on induction of trichomes in Arabidopsis. Artificial damage and jasmonic acid caused significant increases in trichome production of leaves. The jar1-1 mutant exhibited normal trichome induction following treatment with jasmonic acid, suggesting that adenylation of jasmonic acid is not necessary. Salicylic acid had a negative effect on trichome production and consistently reduced the effect of jasmonic acid, suggesting negative cross-talk between the jasmonate and salicylate-dependent defense pathways. Interestingly, the effect of salicylic acid persisted in the nim1-1 mutant, suggesting that the Npr1/Nim1 gene is not downstream of salicylic acid in the negative regulation of trichome production. Last, we found that gibberellin and jasmonic acid had a synergistic effect on the induction of trichomes, suggesting important interactions between these two compounds.

366 citations


Journal ArticleDOI
TL;DR: A dwarf transgenic hybrid poplar was identified after screening of 627 independent activation-tagged transgenic lines in tissue culture, greenhouse, and field environments, and the cause of the phenotype was a hyperactivated gene encoding GA 2-oxidase (GA2ox), the major gibberellin (GA) catabolic enzyme in plants.
Abstract: We identified a dwarf transgenic hybrid poplar (Populus tremula x Populus alba) after screening of 627 independent activation-tagged transgenic lines in tissue culture, greenhouse, and field environments. The cause of the phenotype was a hyperactivated gene encoding GA 2-oxidase (GA2ox), the major gibberellin (GA) catabolic enzyme in plants. The mutation resulted from insertion of a strong transcriptional enhancer near the transcription start site. Overexpression of the poplar GA2ox gene (PtaGA2ox1) caused hyperaccumulation of mRNA transcripts, quantitative shifts in the spectrum of GAs, and similarity in phenotype to transgenic poplars that overexpress a bean (Phaseolus coccineus) GA2ox gene. The poplar PtaGA2ox1 sequence was most closely related to PsGA2ox2 from pea (Pisum sativum) and two poorly known GA2oxs from Arabidopsis (AtGA2ox4 and AtGA2ox5). The dwarf phenotype was reversible through gibberellic acid application to the shoot apex. Transgenic approaches to producing semidwarf trees for use in arboriculture, horticulture, and forestry could have significant economic and environmental benefits, including altered fiber and fruit production, greater ease of management, and reduced risk of spread in wild populations.

241 citations


Journal ArticleDOI
TL;DR: To elucidate if the capacity to produce phytoene is limiting also in the seed of Arabidopsis, a gene coding for an endogenous phy toene synthase was cloned and coupled to a seed-specific promoter, and the effects of the overexpression were examined.
Abstract: Phytoene synthase catalyzes the dimerization of two molecules of geranylgeranyl pyrophosphate to phytoene and has been shown to be rate limiting for the synthesis of carotenoids. To elucidate if the capacity to produce phytoene is limiting also in the seed of Arabidopsis (Wassilewskija), a gene coding for an endogenous phytoene synthase was cloned and coupled to a seed-specific promoter, and the effects of the overexpression were examined. The resulting transgenic plants produced darker seeds, and extracts from the seed of five overexpressing plants had a 43-fold average increase of β-carotene and a total average amount of β-carotene of approximately 260 μg g – 1 fresh weight. Lutein, violaxanthin, and chlorophyll were significantly increased, whereas the levels of zeaxanthin only increased by a factor 1.1. In addition, substantial levels of lycopene and α-carotene were produced in the seeds, whereas only trace amounts were found in the control plants. Seeds from the transgenic plants exhibited delayed germination, and the degree of delay was positively correlated with the increased levels of carotenoids. The abscisic acid levels followed the increase of the carotenoids, and plants having the highest carotenoid levels also had the highest abscisic acid content. Addition of gibberellic acid to the growth medium only partly restored germination of the transgenic seeds.

191 citations


Journal ArticleDOI
TL;DR: It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.
Abstract: Germination of lettuce (Lactuca sativa L. cv. 'Grand Rapids') seeds was inhibited at high temperatures (thermoinhibition). Thermoinhibition at 28 degrees C was prevented by the application of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis. At 33 degrees C, the sensitivity of the seeds to ABA increased, and fluridone on its own was no longer effective. However, a combined application of fluridone and gibberellic acid (GA3) was able to restore the germination. Exogenous GA3 lowered endogenous ABA content in the seeds, enhancing catabolism of ABA and export of the catabolites from the intact seeds. The fluridone application also decreased the ABA content. Consequently, the combined application of fluridone and GA3 decreased the ABA content to a sufficiently low level to allow germination at 33 degrees C. There was no significant temperature-dependent change in endogenous GA1 contents. It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.

179 citations


Journal ArticleDOI
TL;DR: The presence of LeGOLS-1mRNA in ABA-deficient tomato seeds indicated that wild-type amounts of ABA are not necessary for its accumulation during seed development, and GOLS (LeGOLs-1) mRNA accumulated in developing tomato seeds concomitant with maximum dry weight deposition and the acquisition of desiccation tolerance.
Abstract: Raffinose family oligosaccharides (RFOs) have been implicated in mitigating the effects of environmental stresses on plants. In seeds, proposed roles for RFOs include protecting cellular integrity during desiccation and/or imbibition, extending longevity in the dehydrated state, and providing substrates for energy generation during germination. A gene encoding galactinol synthase (GOLS), the first committed enzyme in the biosynthesis of RFOs, was cloned from tomato (Lycopersicon esculentum Mill. cv Moneymaker) seeds, and its expression was characterized in tomato seeds and seedlings. GOLS (LeGOLS-1) mRNA accumulated in developing tomato seeds concomitant with maximum dry weight deposition and the acquisition of desiccation tolerance. LeGOLS-1 mRNA was present in mature, desiccated seeds but declined within 8 h of imbibition in wild-type seeds. However, LeGOLS-1 mRNA accumulated again in imbibed seeds prevented from completing germination by dormancy or water deficit. Gibberellin-deficient (gib-1) seeds maintained LeGOLS-1 mRNA amounts after imbibition unless supplied with gibberellin, whereas abscisic acid (ABA) did not prevent the loss of LeGOLS-1 mRNA from wild-type seeds. The presence of LeGOLS-1 mRNA in ABA-deficient (sitiens) tomato seeds indicated that wild-type amounts of ABA are not necessary for its accumulation during seed development. In all cases, LeGOLS-1 mRNA was most prevalent in the radicle tip. LeGOLS-1 mRNA accumulation was induced by dehydration but not by cold in germinating seeds, whereas both stresses induced LeGOLS-1 mRNA accumulation in seedling leaves. The physiological implications of LeGOLS-1 expression patterns in seeds and leaves are discussed in light of the hypothesized role of RFOs in plant stress tolerance.

148 citations


Journal ArticleDOI
TL;DR: This study is the first to demonstrate the potential of a polyamine-producing actinomycete to promote plant growth and the first published report of the production of polyamines by streptomycetes.
Abstract: Of seventy-five actinomycetes isolated from a bean rhizosphere in the United Arab Emirates, an isolate of Streptomyces griseoluteus (WT) was found to be capable of producing relatively high levels of putrescine on decarboxylase agar medium and to produce putrescine, spermidine and spermine in liquid decarboxylase medium. In the glasshouse, the application of the WT strain to soil amended with arginine (as a precursor for putrescine) significantly (P 0.05) differences between the levels of polyamines, endogenous PGRs, chlorophylls (a, b), and carotenoids between plants that were not exposed to either of the strain (control) and those grown in soil with the PNPM strain. Both WT and PNPM strains were incapable of producing in vitro detectable levels of PGRs, indole-acetic acid, indole-pyruvic acid, gibberellic acid, isopentenyl adenine and zeatin in the culture filtrates. This study is the first to demonstrate the potential of a polyamine-producing actinomycete to promote plant growth. In addition, it is also the first published report of the production of polyamines by streptomycete actinomycetes.

132 citations


Journal ArticleDOI
TL;DR: In this paper, a pot experiment was carried out to study effects of GA3 and cytokinin on the vegetative growth of the soybean, and the results showed that GA3 (50 mg L-1) was applied as seed treatment, leaving plants with water application as control.
Abstract: Soybean is an important crop in Brazil. Nonetheless, there are no reports on the use of plant growth regulator potential in relation to this crop in the national literature. To better understand the role of these compounds, a pot experiment was carried out to study effects of GA3 and cytokinin on the vegetative growth of the soybean. GA3 (50 mg L-1) was applied as seed treatment, leaving plants with water application as control. GA3 (100 mg L-1) and cytokinin (30 mg L-1) were sprayed on leaves at the physiological stage V3/V4, and 15 days after, cytokinin (30 mg L-1), also as foliar spray. Seed treatment decreased plant emergence and initial soybean root growth, but as the season progressed, differences in root growth disappeared; plants were shorter, and presented a decrease in the number of nodes, in stem diameter, in leaf area and in dry matter yield. Conversely, foliar application of GA3 led to an increase in plant height, first node height and stem diameter. Leaf area and dry matter production also increased as a result of GA3 foliar application. There was no effect of exogenous gibberellin and cytokinin on the number of soybean leaves, number of stem branches and root dry matter. Joint application of gibberellin and cytokinin tended to inhibit gibberellin effects. Cytokinin applied to leaves during soybean vegetative growth was not effective in modifying any of the evaluated plant growth variables.

97 citations


Journal ArticleDOI
TL;DR: In situ mRNA hybridization analysis in sections obtained from fungus-infected germinating embryos revealed that ZmPR4 mRNA accumulation occurs in those cell types that first establish contact with the pathogen, and could be part of the general defence response of maize plants against pathogens.
Abstract: Pathogenesis-related (PR) proteins are plant proteins that are induced in response to pathogen attack. PR proteins are grouped into independent families based on their sequences and properties. The PR-4 family comprises class I and class II chitinases. We have isolated a full-length cDNA encoding a chitinase from maize which shares a high degree of nucleotide and amino acid sequence homology with the class II chitinases of the PR-4 family of PR proteins. Our results indicate that fungal infection, and treatment either with fungal elicitors or with moniliformin, a mycotoxin produced by the fungus Fusarium moniliforme, increase the level of ZmPR4 mRNA. In situ mRNA hybridization analysis in sections obtained from fungus-infected germinating embryos revealed that ZmPR4 mRNA accumulation occurs in those cell types that first establish contact with the pathogen. ZmPR4 mRNA accumulation is also stimulated by treatment with silver nitrate whereas the application of the hormones gibberellic acid or acetylsalicylic acid has no effect. Wounding, or treatment with abscisic acid or methyl jasmonate, results in accumulation of ZmPR4 mRNA in maize leaves. Furthermore, the ZmPR4 protein was expressed in Escherichia coli, purified and used to obtain polyclonal antibodies that specifically recognized ZmPR4 in protein extracts from fungus-infected embryos. Accumulation of ZmPR4 mRNA in fungus-infected maize tissues was accompanied by a significant accumulation of the corresponding protein. The possible implications of these findings as part of the general defence response of maize plants against pathogens are discussed.

96 citations


Journal ArticleDOI
TL;DR: Seedling-derived cotyledon explants of squash (Cucurbita pepo L.) of commercial cultivars True French, Ma'yan and Goldy were regenerated in vitro on Murashige and Skoog medium augmented with 1 mg/l benzyladenine to facilitate the recovery of shoots.
Abstract: Seedling-derived cotyledon explants of squash (Cucurbita pepo L.) of commercial cultivars True French, Ma'yan and Goldy were regenerated in vitro on Murashige and Skoog medium augmented with 1 mg/l benzyladenine. After 4 weeks in culture small shoots and buds regenerated only on the most proximal cotyledon edge. Culture on an elongation medium with a reduced cytokinin concentration (0.1 mg/l) with or without 1 mg/l gibberellic acid (GA3) facilitated the recovery of shoots. Fresh shoots could be recovered at each subculture of the regenerating mass. Peak productivity was during the third cycle of subculture, and shoot production ceased after the fifth subculture. Culture on elongation medium supplemented with GA3 was 55% more effective with respect to overall shoot production than that on medium without GA3, with 22 shoots recovered in total per explant from the former. Regeneration occurred under both light and dark conditions. All of the shoots tested were diploid. The shoots were rooted and transferred to the greenhouse where they grew and flowered normally.

81 citations


Journal ArticleDOI
TL;DR: The usefulness of this system for further studies on the genetic transformation of pigeonpea has been demonstrated in biolistics-mediated gene transfer by using nptII and uidA as marker genes, where 50% of the selected plants showed gene integration and expression.
Abstract: A protocol for efficient plant regeneration from leaf explants of pigeonpea [Cajanus cajan (L.) Millsp.] was developed for the production of transgenic plants. Leaf explants from 4- to 5-day-old in vitro raised seedlings were most efficient in producing multiple adventitious shoots in 90% of the explants on shoot induction medium [Murashige and Skoog (MS) medium +5.0 μM benzyladenine +5.0 μM kinetin]. Shoot buds originated from the petiolar cut end of the explants and elongated rapidly on medium containing 0.58 μM gibberellic acid. Over 80% of the elongated shoots rooted well on MS medium containing 11.42 μM indole-3-acetic acid and were transplanted with 100% success. The procedure reported here is very simple, efficient and reproducible, and is applicable across diverse genotypes of pigeonpea. The usefulness of this system for further studies on the genetic transformation of pigeonpea has been demonstrated in biolistics-mediated gene transfer by using nptII and uidA as marker genes, where 50% of the selected plants showed gene integration and expression.

76 citations


Journal ArticleDOI
TL;DR: The feasibility of producing a dwarf (pot) chrysanthemum without the need for growth retardant chemicals through heterologous expression of the mutant Arabidopsis gai gene driven from its own promoter is demonstrated.

Journal ArticleDOI
TL;DR: Germination of Opuntia tomentosa seeds collected during 1998 was evaluated using treatments of scarification, gibberellic acid, GA3, dry heat, soaking, light, after-ripening and stratification at constant and alternating temperatures.

Journal ArticleDOI
TL;DR: In this paper, the efficiency of pretreatment as foliar spray of indole-3-acetic acid, gibberellic acid and kinetin, each ranging from 0.1 to 10.0 μM concentration, in restoring the metabolic alterations imposed by NaCl salinity was investigated.
Abstract: Efficiency of pretreatment as foliar spray of indole-3-acetic acid, gibberellic acid and kinetin, each ranging from 0.1 to 10.0 μM concentration, in restoring the metabolic alterations imposed by NaCl salinity was investigated in Vigna radiata (L.) Wilczek. Glycolate oxidase, superoxide dismutase, catalase and peroxidase activities increased under stress in leaves and roots also. Malondialdehyde content and total peroxide content also increased under stress. All the three hormones used were able to overcome to variable extents the adverse effects of stress imposed by NaCl to these parameters.

Journal ArticleDOI
15 Feb 2003-Planta
TL;DR: Results for gibberellic acid (GA3) and paclobutrazol applications to Carrizo citrange showed that CcGA20ox1 expression was subject to feed-back regulation, and show that the growth reduction induced by environmental and biotic factors may be partially due to the modulation of the expression of GA20ox genes.
Abstract: A cDNA clone coding for a gibberellin (GA) 20-oxidase (CcGA20ox1), an enzyme of GA biosynthesis, which when expressed in vitro catalyzed the conversion of GA12 to GA9 and of GA53 to GA20, was isolated from the citrus hybrid Carrizo citrange (Citrus sinensis × Poncirus trifoliata). Transcripts of CcGA20ox1 were abundant in the apex and leaves and much less abundant in internodes, nodes and roots. Seedlings of Carrizo citrange cultured under a 32 °C/27 °C (day/night) regime elongated more than seedlings growing under 17 °C/12 °C conditions. The effect of higher temperature was associated with more CcGA20ox1 transcripts and with higher content of GA1, the main active GA in citrus, in the shoot. The infection of Etrog citron (Citrus medica) plants with citrus exocortis viroid (CEVd), which produces a stunted phenotype, reduced the levels of transcripts in the apical shoot hybridizing to the gene CcGA20ox1 of Carrizo citrange and the content of GA1. Thus GA1 content correlated with CcGA20ox1 transcript levels. In contrast, results for gibberellic acid (GA3) and paclobutrazol applications to Carrizo citrange showed that CcGA20ox1 expression was subject to feed-back regulation. These observations indicate that the feed-back regulation of GA20ox operates mostly when the levels of active GAs have been dramatically altered. The results also show that the growth reduction induced by environmental (temperature) and biotic (CEVd) factors may be partially due to the modulation of the expression of GA20ox genes.

Journal ArticleDOI
TL;DR: An efficient system for in vitro plant regeneration from thin transversal stem sections explants (1–2 mm) using mature tissues of sweet orange cv.
Abstract: An efficient system for in vitro plant regeneration from thin transversal stem sections explants (1–2 mm) using mature tissues of sweet orange cv Pera was developed Explants were cultured in different media to evaluate the frequency of regeneration and size of buds A high percentage of explants (54% with 31 buds/explant) producing large buds (1–4 mm) was observed when the explants were cultivated for 2 weeks on Murashige and Skoog medium and then transferred to Woody Plant medium (WPM) Both media were supplemented with 18 μM 6-benzylaminopurine and 07 μM gibberellic acid Adventitious buds were regenerated into whole plants by in vitro shoot-tip grafting Regenerated plants started to flower after 12 months in the greenhouse, confirming their mature nature

Journal ArticleDOI
TL;DR: The activities of superoxide-dismutase (SOD), catalase (CAT) and peroxidase (POD), and concentrations of glutathione and ascorbate have been studied during the first stages of germination in Chenopodium rubrum L. seeds.
Abstract: The activities of superoxide-dismutase (SOD), catalase (CAT) and peroxidase (POD), and concentrations of glutathione and ascorbate have been studied during the first stages of germination in Chenopodium rubrum L. seeds. The highest CAT and SOD activity was found prior to radicle protrusion, while POD activity was maximal at the time of radicle protrusion and seedling development, new POD isozymes simultaneously appearing. The concentrations of total, reduced and oxidized glutathione showed similar changes during germination, the highest values being detected at the time of radicle protrusion. Ascorbic acid was present in the seeds in a detectable concentration only at the time preceding radicle protrusion, while its oxidized form dehydroascorbic acid was detected during the whole germination period studied. Gibberellic acid (GA3, 160 μM) had no effect on germination percentage, but in presence of GA3, SOD and CAT activity notably increased prior to radicle protrusion, and oxidized glutathione concentration decreased in further germination.

Journal ArticleDOI
TL;DR: GA3 spraying during flower-bud induction significantly inhibited the activities of PAL, PPO, POD and IAA-oxidase, and increased the level of indole-3-acetic acid (IAA), delaying the biosynthesis of lignin in leaves of the current shoots, as well as inducing the more vigorous growth and inhibiting flower- bud initiation and formation.

Journal ArticleDOI
TL;DR: As a plant model, germinating barley seeds successfully demonstrated the ability of HGA3 to produce a biological response, and the extent and type of response was dependent on the vigour level of the seedlot.

Journal ArticleDOI
TL;DR: It is shown that high carbohydrate levels in the maturation medium significantly increase plant conversion of oak somatic embryos, which exhibit no variation in DNA sequences when proliferated by secondary embryogenesis.

Journal ArticleDOI
TL;DR: A single foliar spray of gibberellic acid at concentrations of 125, 250, 500, or 1,000 mg L−1 induced flowering of Philodendron‘Black Cardinal’ and resulted in more aesthetically pleasing plants than with foliage alone.
Abstract: A single foliar spray of gibberellic acid (GA3) at concentrations of 125, 250, 500, or 1,000 mg L−1 induced flowering of Philodendron‘Black Cardinal’ (an interspecific hybrid developed from a series of crosses among P. wendlandii, hastatum, erubescens, imbe, fragrantissimum, and an unnamed species) in approximately 170 d. Percentage of plants induced and mean flower number per plant increased as GA3 concentrations increased. Compared to unsprayed plants, the number of new leaves decreased, petiole lengths of new leaves and length of the largest leaf increased, but leaf width was unaffected among sprayed plants. One hour before the spathe started to unfurl, spadix temperatures increased, and temperatures in the male portion of the spadix rose by 10 °C above ambient as the spathe fully opened. Elevated temperatures were recorded for about two hours and returned to ambient within five hours. Spathes remained open for about five hours. A creamy white spadix with a contrasting burgundy spathe resulted in more aesthetically pleasing plants than with foliage alone. Because of the short period of display, the open spathe would not increase additional ornamental value of Philodendron‘Black Cardinal’ in the marketplace. However, if breeding is the purpose of flowering induction, spathes should be cut away from the spadix to facilitate pollination.

Journal ArticleDOI
TL;DR: Effects of scarification, giberellic acid and dry heat treatments on the germination of Balanites aegyptiaca seeds from Sudanian savanna in Burkina Faso are studied.
Abstract: Effects of scarification, giberellic acid and dry heat treatments on the germination of Balanites aegyptiaca seeds from Sudanian savanna in Burkina Faso


Journal ArticleDOI
TL;DR: The overall results indicate that although GA3 did not block carbohydrate mobilisation in a irreversibly way, it clearly affected the triggering of starch breakdown and sucrose synthesis, and reinforce the idea of multiple regulatory components in the ripening pathway, as evidenced by the GA3 effects.
Abstract: During banana ripening there is a massive conversion into sugars, mainly sucrose, which can account for more than 10% of the fresh weight of the fruit. An ethylene burst is the trigger of the banana ripening process but there is evidence that other compounds can act as modulators of some biochemical pathways. As previously demonstrated, gibberellic acid (GA3) can impair the onset of starch degradation and affect some degradative enzymes, but effects on the sucrose biosynthetic apparatus have not yet been elucidated. Here, the activity and amount of sucrose synthase (SuSy; E.C. 2.4.1.13) and sucrose–phosphate synthase (SPS; E.C. 2.4.1.14), respiration rates, ethylene production, and carbohydrate levels, were evaluated in GA3-infiltrated and non-infiltrated banana slices. The exogenous supply of gibberellin did not alter the respiration or the ethylene profile but delayed sucrose accumulation by at least 2 days. While SuSy activity was similar in control and treated slices, SPS increase and sucrose accumulation was related in treated slices. Western blotting with specific antiserum showed no apparent effects of GA3 on the amount of SuSy protein, but impaired the increase in SPS protein during ripening. The overall results indicate that although GA3 did not block carbohydrate mobilisation in a irreversibly way, it clearly affected the triggering of starch breakdown and sucrose synthesis. Also, the delayed sucrose accumulation in GA3-infiltrated slices could be explained by the disturbance of SPS activity. In conclusion, gibberellins can play an important role during banana ripening and our results also reinforce the idea of multiple regulatory components in the ripening pathway, as evidenced by the GA3 effects.

Journal ArticleDOI
TL;DR: The results showed that GA3 could be successfully used as a chemical hybridizing agent in hybrid safflower production.
Abstract: The objective of the present research was to develop an effective and practical method for hybrid seed production in safflower, by inducing male sterility with gibberellic acid (GA3). Seeds of the spiny line ‘5-154’ and the non-spiny variety ‘Dincer 5-118’ were sown in alternate rows and the plants of the non-spiny female variety were exposed to various concentrations of GA3 for male sterility induction. Three successive sprays (75, 82 and 89 days after sowing) of 100 p.p.m. of GA3 to safflower buds of <0.5 cm diameter at a pre-meiotic interphase stage resulted in reduced pollen viability from 81.6-6.7% compared with the control. An average hybrid seed percentage of 80.7% (87.5% in the secondary heads), identified by the use of the spiny-capitulum marker variety ‘5-154′, was obtained. The GA3 treatments did not significantly affect the production of viable achenes. The results showed that GA3 could be successfully used as a chemical hybridizing agent in hybrid safflower production.

Journal ArticleDOI
TL;DR: An in vitro germination procedure for cherimoya (Annona cherimola Mill.) seeds, cv.

Journal ArticleDOI
TL;DR: Embryo recovery was improved by excising and culturing ovules at 60 DAF in BD or NN media and then by transferring embryos to WP medium supplemented with BA and AC, and improved greatly in 6-benzyladenine-supplemented woody plant medium containing 0.3% AC.
Abstract: In ovulo embryo rescue techniques have been used to recover new hybrids from seedless × seedless grape crosses. This study was conducted to increase efficiency by investigating effects of genotype, medium, and ovule removal age on ovule elongation, embryo recovery, growth, and plantlet formation. Ovules from self-pollinated berries of seedless varieties Sunmuscat, Merbein Seedless, and Marroo Seedless were cultured at 30, 43, 60, and 70 days after flowering (DAF) in a range of media, some of which were supplemented with gibberellic acid (GA3) and indole-3-acetic acid (IAA). The effect of activated charcoal (AC) in media on rescued embryos was also investigated. Ovules exhibited continuous growth in vivo and in vitro. The most vigorous growth was observed for ovules cultured at 30 and 43 DAF, but more embryos were recovered from ovules cultured at 60 and 70 DAF. Ovule growth and embryo production in vitro were improved in Bouquet and Davis (BD) and Nitsch and Nitsch (NN) media. Supplementation with GA3 increased embryo recovery rates. Highest embryo recovery rates were 18.1%, 9.6%, and 12.2% for Sunmuscat, Merbein Seedless, and Marroo Seedless, respectively, when ovules were excised and cultured at 60 or 70 DAF in either BD or NN media. In vitro embryo survival and plantlet formation were higher for torpedo-shaped embryos, and improved greatly in 6-benzyladenine (BA)-supplemented woody plant (WP) medium containing 0.3% AC. Embryo recovery was improved by excising and culturing ovules at 60 DAF in BD or NN media and then by transferring embryos to WP medium supplemented with BA and AC.

Journal ArticleDOI
TL;DR: Caulogenesis and somatic embryogenesis were induced from transverse thin cell layers (tTCLs) of two European spinach genotypes and regeneration events were obtained from root explants of the cultivar Carpo.
Abstract: Caulogenesis and somatic embryogenesis were induced from transverse thin cell layers (tTCLs) of two European (Spinacia oleracea L) spinach genotypes Regeneration occurred mostly when tTCLs had been excised from seedlings grown on a preconditioning medium consisting of White's macroelements, Nitsch's microelements, Murashige and Skoog's (MS) vitamins, 6 g l−1 agar and 20 g l−1 glucose The explants were cultured on MS medium supplemented with sucrose (10, 30, 50 or 80 g l−1) or fructose (5, 10 or 30 g l−1) and several combinations of indole-3-acetic acid (IAA), α-naphtalene acetic acid (NAA), 6-benzylaminopurine (BAP) and gibberellic acid (GA3) Most of the regeneration events were obtained from root explants of the cultivar Carpo The best result was observed on MS medium supplemented with 50 g l−1 sucrose, 100 μM NAA, 1 μM BAP and 10 μM GA3 After an 8-week culture, the calluses were transferred onto MS medium where shoots and somatic embryos appeared 1 week later The best root development was obtained on MS medium supplemented with 49 μM indole-3-butyric acid (IBA) and 8 g l−1 Phytagel The plantlets were, then, transferred to soil and developed into well-conformed, fertile plants

Journal ArticleDOI
TL;DR: A method specifying inflorescence proliferation to bypass juvenility and maintain the adult phase is developed and it is demonstrated that the regenerated plants still had a juvenile phase and grew normally.
Abstract: Most perennial plants must pass through a long juvenile phase of vegetative development before they are capable of flowering. We have developed a method specifying inflorescence proliferation to bypass juvenility and maintain the adult phase. Bamboo (Bambusa edulis) inflorescences were amplified by incubation in Murashige and Skoog medium supplemented with 0.1 mg/l thidiazuron. Mutant albino inflorescences also proliferated in this medium. This method is equally effective with dicotyledonous plants. Ginseng (Panax ginseng) buds were incubated in B5 medium supplemented with 1 mg/l benzyladenine and 1 mg/l gibberellic acid; new inflorescences developed from the base of the explants. Ginseng flowers were parthenocarpic and some of the fruit proliferated in vitro. Using the inflorescences as the material of somatic embryogenesis, we demonstrated that these were not mutations. The regenerated plants still had a juvenile phase and grew normally.

Journal ArticleDOI
TL;DR: Results indicate that gibberellins are not required for the anaerobic germination of rice grains, and the expression of the Amy3D gene is high under anoxia in the Tan-ginbozu mutant suggesting that germination underAnoxia can proceed thanks to the activity of the α-amylase isoform encoded by the Amy2D gene.
Abstract: Production of α-amylase during the germination of rice grains is thought to play an important role for tolerance to anoxia of these cereal grains. Under aerobic conditions α-amylases production is enhanced in response to gibberellins produced by the embryos, but the role of these hormones is less clear under anoxia. In this paper we analysed α-amylase gene expression in a rice mutant (Tan-ginbozu) severely impaired in gibberellin biosynthesis. Expression of α-amylase genes others than the gibberellin-induced Amy1A gene is observed. The expression of the Amy3D gene, which does dot require gibberellins to be induced, is high under anoxia in the Tan-ginbozu mutant suggesting that germination under anoxia can proceed thanks to the activity of the α-amylase isoform encoded by the Amy3D gene. Amy3D gene expression is repressed in the presence of high levels of soluble carbohydrates, indicating that the anaerobic expression of this gene can be triggered by a lower carbohydrate content of rice grains kept under anoxia. Germination under anoxia of Tan-ginbozu grains can proceed even in absence of exogenously-added gibberellic acid. Overall, results indicate that gibberellins are not required for the anaerobic germination of rice grains.

Journal ArticleDOI
TL;DR: Methods for breaking dormancy and thereby improving germination of Arnebia benthamii, an endangered medicinal herb of the high altitude Himalayas were investigated and reasons for variation in the responses of the two populations and among treatments are discussed.
Abstract: Methods for breaking dormancy and thereby improving germination of Arnebia benthamii (Wall. ex G.Don) Johnston, an endangered medicinal herb of the high altitude Himalayas were investigated. Seeds collected from two populations (alpine and subalpine) were subjected to various treatments, viz; cold stratification (chilling and chilling + gibberellic acid), plant growth substances (gibberellic acid, 6 benzylaminopurine and a Naphthaleneacetic acid) and nitrogenous compounds (thiourea and KNO 3 ). Both the populations differed significantly (p<0.001) in response to various pretreatments. In the alpine population, thiourea (50 mM) significantly (p<0.05) improved germination over that of the control (thiourea 96%; control 42%), whereas in the subalpine population chilling (14 d) resulted in a significant (p<0.05) improvement in germination over that of the control (chilling 14 d, 62%; control 13 %). Reasons for variation in the responses of the two populations and among treatments are discussed.