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Showing papers on "Gibberellic acid published in 2006"


Journal ArticleDOI
TL;DR: The data support an ABA-gibberelic acid hormone balance mechanism controlling cycling through dormant states that depends on synthetic and catabolic pathways of both hormones.
Abstract: Physiologically dormant seeds, like those of Arabidopsis, will cycle through dormant states as seasons change until the environment is favourable for seedling establishment. This phenomenon is widespread in the plant kingdom, but has not been studied at the molecular level. Full-genome microarrays were used for a global transcript analysis of Arabidopsis thaliana (accession Cvi) seeds in a range of dormant and dry after-ripened states during cycling. Principal component analysis of the expression patterns observed showed that they differed in newly imbibed primary dormant seeds, as commonly used in experimental studies, compared with those in the maintained primary and secondary dormant states that exist during cycling. Dormant and after-ripened seeds appear to have equally active although distinct gene expression programmes, dormant seeds having greatly reduced gene expression associated with protein synthesis, potentially controlling the completion of germination. A core set of 442 genes were identified that had higher expression in all dormant states compared with after-ripened states. Abscisic acid (ABA) responsive elements were significantly over-represented in this set of genes the expression of which was enhanced when multiple copies of the elements were present. ABA regulation of dormancy was further supported by expression patterns of key genes in ABA synthesis/catabolism, and dormancy loss in the presence of fluridone. The data support an ABA-gibberelic acid hormone balance mechanism controlling cycling through dormant states that depends on synthetic and catabolic pathways of both hormones. Many of the most highly expressed genes in dormant states were stress-related even in the absence of abiotic stress, indicating that ABA, stress and dormancy responses overlap significantly at the transcriptome level.

392 citations


Journal ArticleDOI
TL;DR: The results suggest that the homeostasis of various plant hormones might be altered in 35S::XERICO plants, possibly by overaccumulation of ABA.
Abstract: Summary RING (really interesting new gene) zinc-finger proteins have important regulatory roles in the development of a variety of organisms. The XERICO gene encodes a small protein (162 amino acids) with an N-terminal trans-membrane domain and a RING-H2 zinc-finger motif located at the C-terminus. In silico gene-expression analysis indicated that XERICO is induced by salt and osmotic stress. Compared with wild-type (WT) Arabidopsis plants, transgenic plants overexpressing XERICO (35S::XERICO) exhibited hypersensitivity to salt and osmotic stress and exogenous abscisic acid (ABA) during germination and early seedling growth. When subjected to a drought treatment, transcriptional upregulation of a key ABA-biosynthesis gene, AtNCED3, was much faster and stronger in 35S::XERICO plants compared with WT plants. Further, upregulation of XERICO substantially increased cellular ABA levels. The adult 35S::XERICO plants, in contrast to early seedling growth, showed a marked increase in their tolerance to drought stress. Yeast two-hybrid screening indicated that XERICO interacts with an E2 ubiquitin-conjugating enzyme (AtUBC8) and ASK1-interacting F-box protein (AtTLP9), which is involved in the ABA-signaling pathway. Affymetrix GeneChip array analysis showed that the expressions of many of the genes involved in the biosynthesis of plant hormones (e.g. ethylene, brassinosteroid, gibberellic acid) were significantly changed in the 35S::XERICO plants. These results suggest that the homeostasis of various plant hormones might be altered in 35S::XERICO plants, possibly by overaccumulation of ABA.

329 citations


Journal ArticleDOI
TL;DR: The aims of the study were to identify the effects of rice endophyte Pantoea agglomerans YS19 on host plant growth and allocations of photosynthates.
Abstract: Aims: The aims of the study were to identify the effects of rice endophyte Pantoea agglomerans YS19 on host plant growth and allocations of photosynthates. Methods and Results: Endophytic diazotrophic YS19 showed nitrogen-fixing activity in N-free medium, and produced four categories of phytohormones which were indole-3-acetic acid, abscisic acid, gibberellic acid and cytokinin in Luria–Bertani medium. Inoculation of YS19 improved the biomass of the 12-day-cultivated host rice seedlings by 63·4% on N-free medium or by 18·7% on N-supplemented medium. Spraying of YS19 cell culture onto the rice plants at the premilk stage enhanced the transportation of the photosynthetic assimilation product from the source (flag leaves) to the sink (stachys) significantly. The formation of the plant sink was obviously inhibited when YS19 cell culture was applied at the late milk stage. Conclusions: This research suggests that endophyte YS19 promotes host rice plant growth and affects allocations of host photosynthates. Significance and Impact of the Study: These findings suggested that YS19 possesses the potential for increasing rice production in field application. Meanwhile, a suitable plant growth stage must be selected for the foliar spraying of YS19 cell culture.

229 citations


Journal ArticleDOI
TL;DR: It is proposed that Scytonema hofmanni extracellular products may counteract altered hormone homeostasis of rice seedlings under salt stress by producing gibberellin-like plant growth regulators.
Abstract: Salt stress is one of the most serious factors limiting the productivity of rice, the staple diet in many countries. Gibberellic acid has been reported to reduce NaCl-induced growth inhibition in some plants including rice. Most paddy soils have a natural population of Cyanobacteria, prokaryotic photosynthethic microorganisms, which synthesize and liberate plant growth regulators such as gibberellins that could exert a natural beneficial effect on salt stressed rice plants. The aim of this work was to evaluate the effect of the cyanobacterium Scytonema hofmanni extracellular products on the growth of rice seedlings inhibited by NaCl and to compare it with the effect of the gibberellic acid in the same stress condition. Growth (length and weight of the seedlings) and biochemical parameters (5-aminolevulinate dehydratase activity, total free porphyrin and pigments content) were evaluated. Salt exposure negatively affected all parameters measured, with the exception of chlorophyll. Chlrorophyll concentrations nearly doubled upon exposure to high salt. Gibberellic acid counteracted the effect of salt on the length and dry weight of the shoot, and on carotenoid and chlorophyll b contents. Extracellular products nullified the salt effect on shoot dry weight and carotenoid content; partially counteracted the effect on shoot length (from 54% to 38% decrease), root dry weight (from 59% to 41% decrease) and total free porphyrin (from 31 to 13% decrease); reduced by 35% the salt increase of chlorophyll a; had no effect on root length and chlorophyll b. Gibberellic acid and extracellular products increased 5-aminolevulinate dehydratase activity over the control without salt. When coincident with high salinity, exposure to either EP or GA3, resulted in a reversal of shoot-related responses to salt stress. We propose that Scytonema hofmanni extracellular products may counteract altered hormone homeostasis of rice seedlings under salt stress by producing gibberellin-like plant growth regulators.

154 citations


Journal ArticleDOI
TL;DR: Results suggested that C. paliurus seeds exhibit both exogenous and endogenous dormancy, and a combination of chemical scarification and exogenous application of GA 3 alleviated seed dormancy in a relatively short period of time.

135 citations


Journal ArticleDOI
TL;DR: The production of transgenic potato shoots within 4 weeks from the time of initial inoculation of leaf explants by Agrobacterium tumefaciens has been established with the Solanum tuberosum subspecies andigena.

107 citations


Journal ArticleDOI
TL;DR: Evidence is provided that butenolide can act in a similar fashion as gibberellic acid in promoting seed germination of light-sensitive seeds, and both compounds were found to stimulate germination.
Abstract: This study investigated the effects of 3-methyl-2H-furo[2,3-c]pyran-2-one, a germination active butenolide present in plant-derived smoke, gibberellic acid and smoke water on seeds of Australian Asteraceae exposed to different light regimes. Seeds of all species required light, with maximum germination occurring under white light, or light dominated by 640 nm. Compared to untreated seeds, butenolide increased germination of Angianthus tomentosus, Gnephosis tenuissima, Myriocephalus guerinae, Podolepis canescens and Rhodanthe citrina at suboptimal light wavelengths and in the dark to a level equal to, or greater than, smoke water. Germination of Erymophyllum glossanthus and Gnephosis acicularis was not promoted by butenolide or smoke water under any light regime. The action of gibberellic acid was compared to that of butenolide for three species (Angianthus tomentosus, Myriocephalus guerinae and Podolepis canescens), and both compounds were found to stimulate germination. This study provides evidence that butenolide can act in a similar fashion as gibberellic acid in promoting seed germination of light-sensitive seeds. The ecological significance of these findings is discussed.

87 citations


Journal ArticleDOI
TL;DR: Germination of African mustard seeds collected from southern Australia was not influenced by light conditions at the optimum temperature but seed germination was inhibited by light at the lower temperature and presence of light increased the sensitivity of seeds to low temperature, as well as salt and osmotic stress.
Abstract: Germination of African mustard seeds collected from southern Australia was not influenced by light conditions at the optimum temperature of 20/12 C. However, seed germination was inhibited by light at the lower temperature (15/9 C). Presence of light increased the sensitivity of seeds to low temperature, as well as salt and osmotic stress. In dark conditions, seed germination was relatively unaffected at a low level of salinity (80 mM NaCl) but decreased even at 10 mM NaCl in light/dark conditions. In the dark, seed germination was unaffected up to an osmotic potential of −0.6 MPa but declined thereafter. Seeds of African mustard germinated over a broad range of pH from 4 to 10. Seed germination was stimulated by potassium nitrate (from 0.005 to 0.04 M) and gibberellic acid (0.001 M). Seedling emergence of African mustard was the greatest (51%) for seeds buried at 1 cm but no seedlings emerged from seeds placed at a depth of 5 cm. At the end of the growing season, seed decay (77 to 87%) and dorma...

77 citations


Journal Article
TL;DR: Irrespective of its concentration, spray of gibberellic acid proved beneficial for most parameters, especially in the case of Hyb-SC-3.
Abstract: A pot experiment was performed according to a factorial randomized design at Aligarh to study the effect of 4 levels of gibberellic acid spray (0, 10 -8 , 10 -6 and 10 -4 M GA3) on the growth, leaf-NPK content, yield and quality parameters of 2 tomato cultivars (Lycopersicon esculentum Mill.), namely Hyb-SC-3 and Hyb-Himalata. Irrespective of its concentration, spray of gibberellic acid proved beneficial for most parameters, especially in the case of Hyb-SC-3.

72 citations


Journal ArticleDOI
TL;DR: The results support the hypothesis that FsPP2C2 is a positive regulator of ABA and indicate the existence of potential cross-talk between ABA signaling and GA biosynthesis.
Abstract: A functional abscisic acid (ABA)-induced protein phosphatase type 2C (PP2C) was previously isolated from beech (Fagus sylvatica) seeds (FsPP2C2). Because transgenic work is not possible in beech, in this study we overexpressed this gene in Arabidopsis (Arabidopsis thaliana) to provide genetic evidence on FsPP2C2 function in seed dormancy and other plant responses. In contrast with other PP2Cs described so far, constitutive expression of FsPP2C2 in Arabidopsis, under the cauliflower mosaic virus 35S promoter, produced enhanced sensitivity to ABA and abiotic stress in seeds and vegetative tissues, dwarf phenotype, and delayed flowering, and all these effects were reversed by gibberellic acid application. The levels of active gibberellins (GAs) were reduced in 35S:FsPP2C2 plants, although transcript levels of AtGA20ox1 and AtGA3ox1 increased, probably as a result of negative feedback regulation, whereas the expression of GASA1 was induced by GAs. Additionally, FsPP2C2-overexpressing plants showed a strong induction of the Responsive to ABA 18 (RAB18) gene. Interestingly, FsPP2C2 contains two nuclear targeting sequences, and transient expression assays revealed that ABA directed this protein to the nucleus. Whereas other plant PP2Cs have been shown to act as negative regulators, our results support the hypothesis that FsPP2C2 is a positive regulator of ABA. Moreover, our results indicate the existence of potential cross-talk between ABA signaling and GA biosynthesis.

66 citations


Journal ArticleDOI
TL;DR: Exogenous application of GA3 improved the water stress tolerance in maize plants by maintaining membrane permeability, enhancing chlorophyll concentration, leaf relative water content (LRWC) and some macro-nutrient concentrations in leaves.
Abstract: The combination effects of water stress and gibberellic acid (GA3) on physiological attributes and nutritional status of maize (Zea mays L. cv., DK 647 F1) were studied in a pot experiment. Maize plants were grown in the control (well watered WW) and water stress subjected to treated both water stress and two concentrations of gibberellic acid (GA3 25 mg L−1, 50 mg L−1). WS was imposed by maintaining the moisture level equivalent to 50 % pot capacity whereas the WW pots were maintained at full pot capacity. Water stress reduced the total dry weight, chlorophyll concentration, and leaf relative water content (RWC), but it increased proline accumulation and electrolyte leakage in maize plants and appears to affect shoots more than roots. Both concentrations of GA3 (25 and 50 mg L−1) largely enhanced the above physiological parameters to levels similar to control. WS reduced leaf Ca2+ and K+ concentrations, but exogenous application of GA3 increased those nutrient levels similar or close to control. Exogenous application of GA3 improved the water stress tolerance in maize plants by maintaining membrane permeability, enhancing chlorophyll concentration, leaf relative water content (LRWC) and some macro-nutrient concentrations in leaves.

Journal ArticleDOI
TL;DR: The hypothesis that carbohydrates may be involved in regulating dormancy status inRoot buds of field-grown leafy spurge had the highest level of innate dormancy from October to November, which persisted until a prolonged period of freezing occurred in November or early December.
Abstract: Signals from both leaves and apical or axillary meristems of leafy spurge are known to inhibit root bud growth. To test the hypothesis that carbohydrates and growth regulators affect root bud growth, decapitated leafy spurge plants were hydroponically treated with glucose, sucrose, gibberellic acid (GA), abscisic acid (ABA), 1-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BA), and a GA biosynthesis inhibitor, paclobutrazol. Both glucose and sucrose caused suppression of root bud growth at concentrations of 30 mM. The inhibitory effect of sucrose was counteracted by GA at 15 μM. In contrast, BA, ABA, NAA, and paclobutrazol inhibited root bud growth at concentrations as low as 1, 2, 1, and 16 μM, respectively. Sugar and starch levels were also determined in root buds at various times after decapitation. Buds of intact plants contained the highest level of sucrose compared with buds harvested 1, 3, and 5 d after decapitation. To determine how seasonal changes affect root bud dormancy, growth fr...


Journal ArticleDOI
TL;DR: The result discussed in this paper indicates that somatic embryos were produced in numbers and converted plantlets can be used as raw material, genetic modification to embryo precursor cell may improve alkaloid yield further.
Abstract: In the present study an efficient somatic embryogenesis method has been developed in Catharanthus roseus. Friable embryogenic callus was induced from hypocotyl of in vitro germinated seeds on Murashige and Skoog basal nutrient media supplemented with various auxins particularly 2,4-D (1.0 mg l−1). However, only NAA (1.0 mg l−1) produced somatic embryos in cultures. Embryo proliferation was even high on the same medium added with BAP. Cotyledonary somatic embryo germinated and converted into plantlets in BAP (0.5 mg l−1) added medium following a treatment with gibberellic acid (1.0 mg l−1) for maturation. Carbon sources and concentrations had a marked influence on maturation process. Plantlet conversion was better achieved when embryos were matured on 3% fructose or 3–6% maltose. The result discussed in this paper indicates that somatic embryos were produced in numbers and converted plantlets can be used as raw material, genetic modification to embryo precursor cell may improve alkaloid yield further.

Journal ArticleDOI
TL;DR: In vitro organogenesis was achieved from callus derived from hypocotyl explants of Cucumis sativus L. cv.
Abstract: In vitro organogenesis was achieved from callus derived from hypocotyl explants of Cucumis sativus L. cv. Poinsett 76. Calli were induced from hypocotyl explants excised from 7-d-old seedlings grown on Murashige and Skoog (MS) medium containing 87.64 µM sucrose, 0.8 % agar, 3.62 µM 2,4-dichlorophenoxy acetic acid and 2.22 µM 6-benzyladenine (BA). Regeneration of adventitious buds from callus (25 shoots explant−1) was achieved on MS medium supplemented with 8.88 µM BA, 2.5 µM zeatin and 10 % coconut water after two subcultures in the same medium at 30-d interval. Gibberellic acid (1.75 µM) favoured shoot elongation and indole 3-butyric acid (7.36 µM) induced rooting. Rooted plants were hardened and successfully established in soil.


01 Jan 2006
TL;DR: It is suggested that recovery effect in starch mobilization and root elongation is in some part regulated by soaking treatment of plant hormones under lower salt stress in rice seed germination.
Abstract: The soaking effects of two plant hormones, gibberellic acid (GA 3) and indole-3-acetic acid (IAA) on dehulled rice seeds exposed to low NaCl stress were investigated. Total soluble and reducing sugars in endosperms of rice seeds soaked with GA 3 (10 &M) increased gradually as germination progressed under low NaCl stress. This increase was more pronounced in IAA-soaked rice seeds than in GA 3-soaked rice seeds. Similarity of +-amylase activity in IAA-soaked germinating rice seeds was much more stimulated than that soaked with GA 3. IAA- and GA 3-soaked rice seeds showed relatively high amounts of endogenous IAA under salt stress. In particular, IAA content increased more in GA 3-soaked rice seeds than in IAA-soaked rice seeds. Furthermore, gibberellin content in IAA-soaked rice seeds showed the highest concentrations among all the treatments. It suggests that recovery effect in starch mobilization and root elongation is in some part regulated by soaking treatment of plant hormones under lower salt stress in rice seed germination.

Journal ArticleDOI
TL;DR: GA3 can be at the origin of an interesting growth rate of vegetative buds, which elongation depend on variety as well as GA3 concentration, which shows that Marsaline seems to be the most able variety in regenerating floral structures.
Abstract: The phytohormone gibberellin is involved in the regulation of many physiological process including flower induction and shoot growth. In this study, gibberellic acid (GA3) was used in order to induce the reversion of olive tree vegetative buds towards a floral ones in vitro. For this, six varieties (Marsaline, Chemchali, Picholine, Chemlali, Zalmati and Oueslati ) was tested and explants, consisting of a single node segments, were grown in media containing three concentrations of GA3 (1, 2 and 10 mg/l). Results show that Marsaline seems to be the most able variety in regenerating floral structures. For this variety, 5 cases of reversion were observed mainly on the medium containing 10 mg/l GA3. This same medium was also favorable for this transformation for the other varieties (3 cases on Picholine, one each on Chemchali , Zalmati and Oueslati). The examination of the histological sections confirmed this transformation. In addition, this experiment showed that GA3 can be at the origin of an interesting growth rate of vegetative buds, which elongation depend on variety as well as GA3 concentration.

Journal ArticleDOI
TL;DR: The application of gibberellic acid during flower bud induction significantly reduced flowering of ‘Black Diamond’ and ‘ Black Gold’ Japanese plums, and this partial inhibition of flowering significantly reduced the cost of manual thinning.

Journal ArticleDOI
TL;DR: This is the first report of successful, micropropagation in an ornamental eucalypt (subgenus Symphyomyrtus) from seedling explants, and the internodes were otherwise very short and unsuitable for multiplication or root initiation.
Abstract: Micropropagation via enhanced axillary shoot proliferation was investigated in the ornamental Eucalyptus cv. ‘Urrbrae Gem’ using in vitro germinated seedlings and was successfully achieved using woody plant medium (WPM) supplemented with 2.2 μM benzylaminopurine, 1.0 μM α-naphthaleneacetic acid, and 1.5 μM gibberellic acid (GA3), gelled with 5 g l−1 Phytagel®. Shoot proliferation was greater on WPM and QL media with GA3 compared to B5, AP, and TK media with or without GA3. GA3 was required for shoot elongation as the internodes were otherwise very short and unsuitable for multiplication or root initiation. Root initiation was improved using (1/2)WPM supplemented with 20 μM indole-3-butyric acid (IBA) over a 7 d pulse, followed by subculture to IBA-free medium, compared to placing shoots on low levels of IBA for 4–6 wk. Plantlets were successfully hardened off to the natural environment via a fogger at 67% relative humidity at 21°C for 3 d and continued to thrive as potted plants. This is the firs...

Journal ArticleDOI
TL;DR: Germination was inhibited by light; however, when seeds were subsequently transferred to complete darkness they germinated readily, and seedling recruitment of both populations was higher under minimum tillage than no-Till conditions, reflecting greater exposure of seeds to light under no-till systems.
Abstract: Threehorn bedstraw is an important dicotyledonous weed in southern Australia that is particularly difficult to control in pulse crops. Knowledge of the germination ecology of this weed would facilitate development of effective weed-control programs. Experiments were conducted to study the germination of two populations, Roseworthy Campus (RC) and Yorke Peninsula (YP), of threehorn bedstraw from South Australia. In the absence of chilling, seeds germinated only in the darkness. Germination was considerably higher under an alternating day/night temperature range of 13/7 C compared with 20/12 or 25/15 C day/night temperature. Germination was inhibited by light; however, when seeds were subsequently transferred to complete darkness they germinated readily. Potassium nitrate (0.005 M KNO3) and gibberellic acid (0.001 M GA3) stimulated germination in the darkness in both populations. This concentration of KNO3 increased germination of the RC and YP populations from 26 and 37% to 56 and 68%, respectivel...


Journal ArticleDOI
TL;DR: Evidence from the present study indicates that S. nux-vomica seeds possess physiological dormancy that can be broken effectively by after-ripening, and dry seed (10% moisture content) can be hermitically stored at ambient temperature for 30 weeks without losing their viability.
Abstract: Seeds of Strychnos nux-vomica have slow and erratic germination; thus different presowing treatments were applied to enhance the germination of its seeds collected from Tamaraikulam, Tamil Nadu, India. In addition, the effects of desiccation and different storage conditions on the germination of S. nux-vomica seeds were investigated. The results show that soaking in 500 ppm gibberellic acid (GA3) for 24 h, incubation of seeds at 40 °C for 3 days and alternate water soaking (16 h) and drying (8 h) for 14 days significantly increased the percentage germination compared to the control. Desiccation of seeds down to 10% moisture content resulted in better germination. Germination of S. nux-vomica seeds differed significantly between different storage periods, moisture contents of the seed and for first and second order interactions (p<0.001). The highest germination (92%) was achieved when seeds with 10% moisture content were stored at ambient temperature for 30 weeks. Evidence from the present study indicates that S. nux-vomica seeds possess physiological dormancy that can be broken effectively by after-ripening. As seeds of S. nux-vomica are found to be desiccation tolerant, dry seed (10% moisture content) can be hermitically stored at ambient temperature for 30 weeks without losing their viability.

Journal ArticleDOI
TL;DR: It is revealed that conclusions based on one population of Hypericum perforatum cannot characterize the germination behaviour for the entire species, and seed germination percentages are highly variable depending on the accession.
Abstract: Germplasm conservation of medicinal plants is of increasing interest and, when possible, seed banking is the most efficient system for ex situ conservation of these plant genetic resources. Hypericum perforatum L. (St. John's wort, Guttiferae) is a medicinal plant with evidence of efficacy as an anti-depressant. The aim of this work was to increase knowledge of its seed germination behaviour by studying 68 wild populations. Seed germination tests were carried out at 25/15 °C under a photoperiod of 16-h light/8-h darkness. Final germination percentages were highly variable depending on the accession, ranging from 6 to 98%. Similarly, germination rate (as expressed by T 50 values) varied significantly from 6.1 to 23.0 days. The effect of seed desiccation with silica gel on subsequent germination was also studied. The effect of two other incubation temperatures (15 and 25 °C) and light (photoperiod or darkness) on seed germination was studied in several accessions. Temperature had no significant effect on final germination percentages. However, light significantly increased the germination of most but not all accessions assayed. Seeds from four accessions with low germination percentages were subjected to different presowing treatments that could increase germination: dry heat, hot water and gibberellic acid. Germination was promoted significantly by gibberellic acid in two of the four accessions assayed, but the thermal treatments did not enhance significantly the germination percentages. This study reveals that conclusions based on one population of Hypericum perforatum cannot characterize the germination behaviour for the entire species.

Journal ArticleDOI
TL;DR: Peat followed by volcanic tuff gave the best performance for acclimatization to outdoor conditions and the clone 37 displayed a higher performance than clones 50 and 82 through tissue culture.
Abstract: This experiment is designed to determine the most suitable conditions and media for propagating three selected fig (Ficus carica L.) clones through tissue culture. The clone 37 displayed a higher performance than clones 50 and 82. As the multiplication medium, the Murashige and Skoog (MS) medium containing 1 mg dm−3 α-indole-3-butyric acid (IBA), 1 mg dm−3 gibberellic acid and 5 mg dm−3 6-benzyladenine were the best, whereas, MS medium complemented with 1.2 and 2.5 μM IBA or 1-naphthalene acetic acid (NAA) were better in respect to rooting. Peat followed by volcanic tuff gave the best performance for acclimatization to outdoor conditions.

Journal Article
TL;DR: Effect of cadmium on barley seeds treated with kinetin and gibberellic acid was investigated, and Cadmium showed important inhibitory effects on roots and coleoptile growth after germination.
Abstract: Effect of cadmium on barley seeds treated with kinetin and gibberellic acid was investigated. As usual, cadmium has inhibited seed germination, and showed important inhibitory effects on roots and coleoptile growth after germination. In general, increase in cadmium concentration caused a greater inhibition of germination, root and coleoptile growth. The adverse effect of cadmium on root and coleoptile growth was more pronounced than that on germination. While testa was pierced by radicle (an indication of germination), no root or coleoptile development was observed above at concentration of 3-9.5 mM CdCl2xH2O. Low concentrations of cadmium have inhibited the root growth more than it did on coleoptile growth. Treatment of seeds with gibberellic acid and kinetin did not show any significant difference on the effect of cadmium in germination. However, inhibition of coleoptile elongation by cadmium has decreased a very much after kinetin application. The same result, although with lower rates when compared to kinetin, has been obtained for GA3 as well. In addition, the inhibitory effect of cadmium on root growth increased even more after kinetin application. The results have been found statistically significant through the least significant different (LSD) test at levels ofp < 0.05 and p < 0.01.

Journal ArticleDOI
TL;DR: Somatic embryos of carob were induced from cotyledonary segments excised from immature seeds when cultured on Murashige and Skoog media supplemented with several combinations of 6-benzylaminopurine (BA) and indole-3-butyric acid (IBA).
Abstract: Somatic embryos of carob (Ceratonia siliqua L.) were induced from cotyledonary segments excised from immature seeds when cultured on Murashige and Skoog media supplemented with several combinations of 6-benzylaminopurine (BA) and indole-3-butyric acid (IBA). The best frequencies of induction (33.8%) were obtained when 4.4 μM BA and 0.5 μM IBA were used. Shoots were also sporadically formed in the same media. When IBA was replaced by other auxins in the induction media, only α-naphthaleneacetic acid (NAA) and indole-3-acetic acid (IAA) could induce somatic embryogenesis, although at lower rates than IBA. 2,4-Dichlorophenoxyacetic acid and 4-amino-3,5,6-trichloropicolinic acid were completely ineffective. Besides culture media composition, the developmental stage of the explants at the time of culture showed a strong influence on somatic embryogenesis induction, with cotyledons from stage II pods providing the highest levels of induction. By contrast, the genotype of the explant did not determine a significant role in the induction process. Attempts to achieve somatic embryo germination were mostly unsuccessful, since only shoot development was observed; the highest frequencies of development occurred on media containing only gibberellic acid (3.0 μM). For plant regeneration, the developed shoots were further rooted on IBA-supplemented media, and the plantlets obtained were transferred to soil, where c. 88% of them survived. Histological observations showed the presence of morphologically normal and abnormal somatic embryos, the latter displaying an abnormal pattern of vascular bundles. Ultrastructural analysis showed that the cells of the globular embryos had a dense cytoplasm, whereas those not involved in somatic embryo formation showed signs of senescence. Histological studies were also used to distinguish between somatic embryos and shoots originated in the same media.

Journal ArticleDOI
TL;DR: In this article, the authors used drenches of Gibberellic acid (GA 3 )(2.5 or 5 mM), N 6 -benzyladenine (BA) (25 or 50 mM) alone or in combination.
Abstract: Flowering of Miltoniopsis orchids is influenced by a combination of cool temperatures and short photoperiod. To determine if application of plant growth regulators could promote flowering without the need for costly structural modification to control photoperiod or temperature, we used drenches ofgibberellic acid (GA 3 )(2.5 or 5 mM), N 6 -benzyladenine (BA) (25 or 50 mM) alone or in combination. BA (25 or 50 mM) treatments promoted new vegetative shoots and decreased the number of plants with inflorescences compared to the untreated control plants. This reduction of flowering and increased vegetative shoot production was alleviated by the addition of GA 3 in combination with BA. However, the number of plants with inflorescences remained less than the control. GA 3 hastened Miltoniopsis inflorescence emergence during the first flowering season by 10.9 to 14.9 days for Bert Field 'Eileen' and by 48.7 days for Rouge 'Akatsuka'. The number of 'Eileen' inflorescences produced per plant increased from 2.2 to 3.0 with 2.5 mM GA 3 treatment. Flower deformities were not observed in the GA 3 treated plants, and flower size and inflorescence length were unaffected by the GA 3 treatment.

Journal ArticleDOI
TL;DR: Application of GA3 30 DAT significantly increased plant height and the number, but not the weight, of tubers formed per plant and daminozide and CCC reduced plant height when applied 30 but not 60 d after transplanting (DAT) in both spring and autumn.
Abstract: The effects of plant growth regulators [6-benzyl amino purine (BA), indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D), gibberellic acid (GA3), chlormequat chloride (CCC), daminozide] and their time of application on tuberisation and physiological age of cv. Chacasina F1 grown from true potato seed (TPS) were studied in four experiments conducted in spring or autumn in Greece. BA, IAA and 2,4-D did not affect plant development, tuberisation or the physiological age of the tubers produced. Daminozide and CCC reduced plant height when applied 30 but not 60 d after transplanting (DAT) in both spring and autumn. Neither substance affected tuberisation or the physiological age of the tubers formed. Application of GA3 30 DAT significantly increased plant height and the number, but not the weight, of tubers formed per plant. Tubers from GA3-treated plants tended to be elongated with a low dry matter content. When GA3 was applied at 60 DAT, plant height was increased, but tuber number, weight and ...

Journal ArticleDOI
TL;DR: Galeopsis speciosa has a strong dormancy that is sufficiently alleviated during the winter to allow germination of only part of a seed batch each year, hence a stepwise germination pattern occurs over a period of several years.
Abstract: This study examined germination and dormancy in Galeopsis speciosa (Lamiaceae), a common summer annual weed in cold-temperate areas. Seeds collected in southern Sweden were subjected to several experiments. The seeds were dormant at maturity. Seeds sown outdoors after collection produced a small number of seedlings, that emerged early in the spring. After long cold stratification or stratification outdoors over two winters, the maximum germination was 40 to 50%; germination occurring over a wide range of temperatures. Warm stratification preceding cold stratification had no effect on germination, but repeated warm and cold periods seemed to promote germination. Gibberellic acid (GA) stimulated germination but full germination was only achieved after more than two months of incubation at the most suitable temperature regime tested. Excised embryos grew and developed into normal seedlings. With these results, the species does not fit into the currently used system for seed dormancy classifications. The response to GA and the growth of excised embryos indicate non-deep or intermediate physiological dormancy, but dormancy alleviation by stratification was not in line with the guiding principles for these classifications. Galeopsis speciosa has a strong dormancy that is sufficiently alleviated during the winter to allow germination of only part of a seed batch each year, hence a stepwise germination pattern occurs over a period of several years.