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  • 2000-2004  (20)
  • 1955-1959  (9)
  • Brassica napus
  • somaclonal variation
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 100 (2000), S. 895-898 
    ISSN: 1432-2242
    Schlagwort(e): Key words Diallel analysis ; Regeneration ability ; Cotyledonary culture ; Brassica napus ; Heritablity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Genetic analysis of shoot regeneration from cotyledonary explants of Brassica napus was carried out by 7×7 diallel crosses using cultivars showing a different ability for regeneration. Both additive and dominant effects were significant, with the additive effect being more important than the dominant one. Dominant genes had a positive effect on shoot regeneration. Non-allelic interaction and average maternal effects were not detected, while specific the maternal one was significant. In the 5×5 sub-diallel table, the maternal effect became nonsignificant. The mean degree of dominance was 0.759. Broad- and narrow-sense heritabilities were 0.973 and 0.819, respectively, indicating that shoot regenera- tion ability can be easily transferred into economically important cultivars showing a low or an unresponsive ability.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-2242
    Schlagwort(e): Key words. Fertility Restoration (Rf) ; Cytoplasmic male sterility (CMS) ; Raphanus sativus L. ; Brassica napus ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The genetics of fertility restoration (Rf) of kosena radish CMS has been characterized. The kosena CMS-Rf system is genetically the same as that of the ogura CMS-Rf system. Two dominant genes that act complementary to the restoration of fertility control fertility restoration in kosena CMS. One allele (Rf1) is associated with accumulation of the CMS-associated protein, ORF125. The interaction of Rf1 and another allele (Rf2) was essential for the restoration of fertility in radish, whereas Rf1 alone was sufficient for the complete restoration of fertility in the B. napus kosena CMS cybrid.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell reports 19 (2000), S. 1177-1183 
    ISSN: 1432-203X
    Schlagwort(e): Keywords Rapid-cycling ; Brassica napus ; Somatic embryogenesis ; Secondary embryogenesis ; Regeneration ; In vitro Howering ; AbbreviationsABA: Abscisic acid ; BAP: 6-Benzyl-aminopurine ; DAP: Days after pollination ; 2-iP: 6-(γ, γ-dimethlyallyl-amino)purine ; Kinetin: 6-Furfurylaminopurine ; MS: Murashige and Skoog ; SE0: Somatic embryo from seed ; SE1: First-generation secondary embryo ; SE2: Second-generation secondary embryo ; Zeatin: 6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A simple method to induce somatic embryogenesis from seeds of rapid-cycling Brassica napus is described. Seedlings cultured on Murashige and Skoog (MS) basal medium produced somatic embryos directly on hypocotyls and cotyledons after 2 to 3 subcultures onto the same medium. A low pH of the medium (3.5–5) was more conducive to somatic embryogenesis than a higher pH (6 and 7). Embryogenic potential of the seeds was inversely correlated to seed age: about 41–68% of immature seeds between the ages of 14 and 28 days after pollination (DAP) formed somatic embryos compared to 0–11% of the seeds obtained 29–37 DAP. About 54% of the somatic embryos produced secondary embryos after subculturing onto the same medium. The embryogenic potential of the cultures has been maintained on MS basal medium for 2 years (12 generations) without diminution. Up to 75% of the secondary embryos developed into plantlets on MS medium enriched with 10–6  M zeatin, and 40% of these produced flowers when transferred to an optimised flower-induction medium. Viable seeds were produced in self-pollinated in vitro flowers.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2145
    Schlagwort(e): Key words Freeze-substitution ; Transmission electron microscopy ; Brassica napus ; Tapetum ; Microspore ; Immunogold
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The method of rapid freeze-fixation and substitution was used with Brassica napus floral bud material in order to improve the preservation of microspore and tapetal organelle structure. When observed using transmission electron microscopy, the appearance of the freeze-substituted material differs in a number of ways from the chemically-fixed material previously studied, in particular for the lipid-rich elaioplasts and tapetosomes in the tapetal cells. The tapetosomes have a very electron-dense, opaque appearance when visualized after rapid fixation. In addition, we were able to observe other cytoplasmic details such as pockets in the endoplasmic reticulum and cytoskeletal structures such as microfilaments. Extracellular material was also well-preserved; for example, the fibrous material in the baculae of the developing microspore exine was also visible. Finally, in the freeze-fixed sections specific structures such as elaioplasts could be labelled by antibodies, which indicates that this method preserved protein epitopes that were destroyed by chemical fixation.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-2145
    Schlagwort(e): Key words Gene-specific expression ; skp1-like gene ; GUS staining ; Gametophytic expression ; Brassica napus ; Arabidopsis thaliana
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We isolated a gene, BnSKP1γ1, expressed in rapeseed (Brassica napus) microspores, which encodes a protein closely related to the Saccharomyces cerevisiae Skp1p protein previously shown to play a role in cell cycle regulation. Twelve SKP1-related genes have already been identified in the Arabidopsis thaliana genome. Using a PCR-based strategy, we isolated three other genes. To date, most data available concerning the function of the SKP1-related genes in plants are indirect. Studies on transgenic A. thaliana plants showthat a 1100-bp BnSKP1γ1 promoter fragment can direct GUS expression in female gametophytes soon after the first haploid mitosis and in male gametophytes from the tetrade stage. No GUS expression can be detected in sporophytic tissues. RT-PCR experiments suggest that this gene is expressed in a similar way in rapeseed. This is the first reported case of a gene exhibiting such an expression pattern in angiosperms.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Biologia plantarum 43 (2000), S. 157-160 
    ISSN: 1573-8264
    Schlagwort(e): apical dominance ; in vitro flowering ; regeneration ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The morphogenetic responses of cotyledonary nodal explants of Vigna mungo (L.) Hepper cv. VBN1 cultured on the same Murashige and Skoog's medium, B5 vitamins, and 13.31 µM N6-benzylaminopurine showed variations in the pattern of multiple shooting and morphology of leaves in dependence on initial explants (presence/absence of cotyledons). The regenerated shoots elongated in the initial medium and most of them rooted in the presence of 2.41 µM indole-3-butyric acid, and flowered in vitro. Rooted plants could be transferred to the field after hardening.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Biologia plantarum 43 (2000), S. 161-165 
    ISSN: 1573-8264
    Schlagwort(e): grain legumes ; pea ; regeneration in vitro ; somaclonal variation ; variant phenotype
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A sterile mutant of pea (Pisum sativum L. line HM-6) with a number of morphological alterations was found after plant regeneration via somatic embryogenesis. Embryogenic callus was derived from the whole immature zygotic embryo on medium with 2.26 μM 2,4-dichlorophenoxyacetic acid. Morphological changes included altered leaflet shape, one pair of leaflets only, altered stipule morphology, shortened internodia, irregular or opposite leaf position on the stem, shortened flower stalk, and aborted flowers resulting in complete sterility. If the isolation of the shoot apex and axillary buds from evidently sterile plant and their culture in vitro resulted in morphologically normal and fertile regenerated plants, the chimaeric nature of R0 mutant is considered.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1573-1561
    Schlagwort(e): Brassica napus ; Pratylenchus neglectus ; nematode ; 2-phenylethyl glucosinolate ; isothiocyanate ; pest resistance ; disease break ; variability ; genetic analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Root concentrations of 2-phenylethyl glucosinolate in canola, Brassica napus, influence the susceptibility of the crop to the root lesion nematode (Pratylenchus neglectus), as well as the nematicidal effect of root tissues as they degrade in the soil. Plants containing high 2-phenylethyl glucosinolate should therefore reduce soil populations of P. neglectus. A selection program was developed to increase the proportion of total glucosinolates contributed by 2-phenylethyl glucosinolate in the roots of B. napus cv. Dunkeld. Variation within this accession was observed to be stable across the S1 and S2 generations. The segregation observed for 2-phenylethyl glucosinolate percentage suggested that the trait was encoded at a single locus, with the "high" phenotype being dominant. Plants with the high 2-phenylethyl glucosinolate phenotype (〉45% of total glucosinolates) were shown to be significantly more resistant to P. neglectus than otherwise identical "low" phenotypes (〈45% of total).
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 26 (2000), S. 1411-1422 
    ISSN: 1573-1561
    Schlagwort(e): Brassica napus ; defense-related proteins ; environmental effects ; induced defenses ; proteinase inhibitors ; regulation ; resistance ; trypsin inhibitors ; variation ; wounding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract We examined several environmental and developmental influences on trypsin inhibitor (TI) activity in leaves of young Brassica napus seedlings in a series of greenhouse experiments. In seedlings of B. napus cv. Westar, TI activity is constitutively present and exhibits a rise then fall through time in the first true leaves of young plants. TI activity is induced by wounding in the first true leaves, but the degree of induction is relatively insensitive to the degree of wounding over a gradient of 5–15% of leaf area damage. TI activity is enhanced in first true leaves of plants in which the cotyledons have been wounded relative to plants in which the cotyledons have not been wounded. TI activity is also enhanced in the second true leaves on plants in which the first true leaves have been wounded. The degree of systemic induction in second true leaves declines additively with plant age, but local induction in the first true leaves is not affected by age. In B. napus cv. Gido, TI activity is constitutively present but is not locally wound-inducible in first true leaves of young plants exposed to the same wounding gradient as cv. Westar. In unwounded plants at the six-leaf stage, TI activity is higher in second true leaves than in fifth true leaves, indicating that TI activity is developmentally regulated in this cultivar.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 26 (2000), S. 2387-2399 
    ISSN: 1573-1561
    Schlagwort(e): Rhizopus spp. ; Fusarium spp. ; rhizosphere microorganisms ; Brassicaceae ; Rorippa sylvestris ; Brassica napus ; Brassica juncea ; Lepidium sativum ; myrosinase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract We isolated several strains of Rhizopus and Fusarium spp. as dominant fungi in the rhizospheres of Brassicaceae plants. The Fusarium isolates showed a higher tolerance of the antifungal constituents of "mustard oil," which originates from the glucosinolates that are characteristic secondary metabolites of the Brassicaceae, than other Fusarium isolates from non-Brassicaceae plants. In contrast, the Rhizopus isolates showed a high tolerance regardless of their source. Myrosinase activity was found in Bn-R-1-1 (Rhizopus sp.) isolated from the rhizoplane of Brassica napus and Ls-F-in-4-1 (Fusarium sp.) isolated from a surface-disinfected root of Lepidium sativum (Brassicaceae). Ls-F-in-4-1 was the Fusarium most tolerant of the Brassicaceae antifungal constituents. These results suggest that fungi in the rhizospheres of Brassicaceae plants may be selected because of secondary metabolites exuded from the roots of host plants.
    Materialart: Digitale Medien
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  • 11
    ISSN: 1570-7458
    Schlagwort(e): Ceutorhynchus assimilis ; Trichomalus perfectus ; Brassica napus ; cabbage seed weevil ; parasitoid ; oilseed rape ; spatio-temporal distribution ; SADIE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The spatio-temporal distribution of Ceutorhynchus assimilis Payk. (Coleoptera: Curculionidae) adults caught in a rectangular grid of flight traps in a crop of winter oilseed rape (Brassica napus L.) was mapped and was analysed using Spatial Analysis by Distance IndicEs (SADIE). Their distribution was compared to that of their larvae and that of their parasitoid Trichomalus perfectus (Walker) (Hymenoptera: Pteromalidae) in pods. The distribution of immigrating C. assimilis adults was consistent with their arrival at the crop boundaries and movement within the crop towards its centre. Adult C. assimilis were aggregated at all times, invasion being on two fronts, leading to the formation of two major clusters within the crop. Large areas of the crop remained relatively unpopulated. During the emigration phase, numbers declined simultaneously in all parts of the crop. The distributions of adult and larval C. assimilis and of larval T. perfectus were spatially associated. The distribution of the parasitoid did not show a density dependent relationship with that of its host. We discuss the movements of insects which underlie their population distributions, the value of integrating spatial information into improved management strategies for C. assimilis and the potential for the spatial targeting of insecticides to reduce the amount applied and to conserve T. perfectus.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; doubled haploids ; high oleic acid rapeseed (HOAR) ; in vitro selection ; microsporeculture ; mutants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Microspore derived embryos (MDEs) in Brassica napuscontain large amounts of storage lipids which show a genotype specific fatty acid composition (FAC). One cotyledon of regenerating emblyos can be dissected at an early stage during the in vitro culture and used for fatty acid analysis. Thus, in breeding programmes to modify oil quality, only MDEs having the desired FAC need to be regenerated to plantlets and transferred to the greenhouse. In the present study the applicability of this method for the selection of a high oleic acid content and a low linoleic acid content in the seed oil has been tested by crossing a Brassica napus mutant line having a high oleic acid (C18:1) content in the seed oil (75%) with a wild type doubled haploid line with 62% C18:1 in the seed oil. Microspore culture was applied to the F1 plants. In total 59 MDEs were obtained, from which 31 were cultured with and 28 without 15μM abscisic acid for 3 weeksin vitro. One cotyledon was dissected under aspetic conditions and used for fatty acid analysis. The remaining part of the embryos were further regenerated to plantlets and transferred to the greenhouse to obtain seeds after self pollination. Seeds harvested from the doubled haploid lines in the greenhouse were used for fatty acid analysis and also for growing in the field. The abscisic acid treatment of the MDEs generally improved the correlations for linoleic and oleic acid between the MDEs and the seeds harvested in the greenhouse and the field. The correlations ranged from 0.68** to 0.81**.This indicates that selection for high oleic acid can be started already during an early stage of the in vitro culture.
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  • 13
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; germination test ; herbicidetolerance screening ; monitoring ; PAT-ELISA ; PCR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A novel screening test is described for the discrimination of transgenic phosphinothricin tolerant oilseed rape from non transgenic rape seedlings. The method is based on the germination of rape seeds on filter paper soaked with a 0.005% phosphinothricin solution. Under these conditions inhibition of seedling development by the herbicide can be observed after 10 days. The germination test gains an advantage over the routinely used herbicide spraying, because it is rapid, needs little space and allows efficient screening of huge numbers of seeds. The assay has been successfully applied to the screening of different transgenic and non transgenic rapeseed varieties/lines and has been compared to other methods such asBasta® spray test, drop test, ELISA-technique and PCR-amplification of the pat gene. This test allows on one hand large screening programmes to monitor the foreign gene in the environment and on the other quality control of seedlots before market introduction of herbicide tolerant oilseed rape.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 113 (2000), S. 207-210 
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; hybrid seed production ; self-incompatibility ; swedes, rutabaga
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Procedures for producing seed of hybrid swedes using self-incompatibility were examined. Single-cross, double-cross and modified double-cross hybrids were compared in isolation plots using natural pollinators and in polythene tunnels using blow-flies. With good coincidence of flowering and the same flower colour, nearly 100% hybrid seed was produced by natural pollinators with the single-crosses, the double-cross and one of the two modified double-cross hybrids; the other modified double-cross hybrid produced 87%hybrid seed. With poor coincidence of flowering and different flower colours the proportion of hybrids dropped to 61%. Using different flower colours and blow-flies as pollinators in polythene tunnels, higher levels of outcrossing were produced than in isolation plots with natural pollinators; the opposite result was obtained when the same flower colour was used.
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Photosynthesis research 64 (2000), S. 137-146 
    ISSN: 1573-5079
    Schlagwort(e): Brassica napus ; chlorophyll ; chlorophyll catabolite ; degradation ; porphyrin ; senescence ; tetrapyrrole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chlorophyll catabolism accompanying leaf senescence is one of the most spectacular natural phenomena. Despite this fact, the metabolism of chlorophyll has been largely neglegted until recently. Oilseed rape has been used extensively as a model plant for the recent elucidating of structures of chlorophyll catabolites and for investigation of the enzymic reactions of the chlorophyll breakdown pathway. The key reaction which causes loss of green color is catalyzed in a two-step reaction by pheophorbide a oxygenase and red chlorophyll catabolite reductase. In this Minireview, we summarize the actual knowledge about catabolites and enzymes of chlorophyll catabolism in oilseed rape and discuss the significance of this pathway in respect to chlorophyll degradation during Brassica napus seed development.
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 114 (2000), S. 217-221 
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; flower receptacle segments ; in vitro ; culture ; pollinated ovaries ; Raphanus sativus var. raphanistroides/kwd〉
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Oil radish (Raphanus sativus var. raphanistroides Makino) is resistant to drought and low temperature. In order to breed more resistant cultivars of rapeseed, the wide cross between rapeseed (Brassica napus L.) and oil radish was made. Rapeseed was not compatible with oil radish, and the frequency of hybrid plants (F1) was very low. Moreover, the hybrid plants were sterile. In order to recover the intergeneric hybrids (F1), the in vitro organ culture technique was applied in our experiments. The frequency of hybrid plants (F1) was increased up to 25.55% by means of in vitro culture of pollinated ovaries. Some fertile amphidiploid hybrid plants were obtained by means of colchicine treatment of small buds obtained from cultured flower receptacle segments of hybrid plants (F1). It is suggested that the technique of in vitro culture of pollinated ovaries and flower receptacle segments is useful in the wide-cross breeding of rapeseed.
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  • 17
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; fatty acid composition ; tissueculture-induced variation ; transformation-induced variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The variation obtained in storage fatty acids induced by the procedures of tissue culture and transformation with Agrobacterium tumefaciens was investigated and compared in rapeseed, Brassica napus, cv. Hanna. An increased variation in the fatty acid profiles was noted after tissue culture and transformation compared with plants derived directly from seeds. In the second generation of rapeseed transformants, T2, the content of oleic acid ranged from 39–72%, 12–31% for linoleic acid and 7–16% for linolenic acid. This could be compared with the oleic acid content in the T2 generation of tissue culture-derived plants which ranged between 47–76% and in seed-derived material where oleic acid ranged between 55–69%.In the T3 generation the ranges in transgenic seeds were decreased but still larger than in the seed derived plants. The range in transgenic plants was 49–64% for oleic acid, 20–28% for linoleic acid and 9–18% for linolenic acid. The most extreme individuals, both highest and lowest in the common fatty acids, were found in the group of transformed plants independent of generation. The total lipid content was also affected by the two treatments and seeds with the lowest and highest lipid content were both found among the transformed plants. In conclusion, care should be taken to use proper controls when performing transformation experiments in order to distinguish variation in the fatty acid profiles induced by the transformation procedure and tissue culture treatments from the changes due to transgenic expression.
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  • 18
    ISSN: 1573-5060
    Schlagwort(e): banana ; embryogenic cell suspension ; micropropagation ; Musa ; somaclonal variation ; somatic embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Growth and yield characteristics of two different clones of banana plants (Musa AAA cv. Grande naine) originating from four months old embryogenic cell suspensions were studied. These characteristics were compared with those plants produced by the conventional in vitro budding multiplication method. Two types of variants were observed during the acclimatization phase among 500 embryogenic cell suspension derived plants. The first type related to banana plants with `variegated or deformed leaves' were also observed in in vitro budding derived plants. The second type concerned `fasciated-leafed' plants. During the field growth, these two variant types produced plants morphologically similar to the other plants. Thus, none of the cell suspension derived plants exhibited off-type traits in the field. A Fisher block model was used to compare the field performances of the two clones produced through the two in vitro propagation techniques. The analysis of variance showed that there were no significant differences between the plants produced by either micropropagation techniques for the plant height and circumference, the length of the reference leaf, the number of nodal clusters of the inflorescence and of fruits, the bunch weight, the period of time between planting and flowering, and between planting and harvesting. This study showed that banana plants with an agronomical behaviour similar to those produced by the conventional in vitro budding method could be regenerated from embryogenic cell suspension.
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  • 19
    ISSN: 1615-6102
    Schlagwort(e): Actin microfilament ; Brassica napus ; Cytochalasin D ; Microspore embryogenesis ; Microtubule ; Preprophase band
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Changes in the actin filament and microtubule cytoskeleton were examined during heat- and cytochalasin D-induced embryogenesis in microspores ofBrassica napus cv. Topas by rhodamine phalloidin and immunofluorescence labelling respectively. The nucleus was displaced from its peripheral to a more central position in the cell, and perinuclear actin microfilaments and microtubules extended onto the cytoplasm. Heat treatment induced the formation of a preprophase band of microtubules in microspores; preprophase bands are not associated with the first pollen mitosis. Actin filament association with the preprophase band was not observed. The orientation and position of the mitotic spindle were altered, and it was surrounded with randomly oriented microfilaments. The phragmoplast contained microfilaments and microtubules, as in pollen mitosis I, but it assumed a more central position. Cytoskeletal reorganisation also occurred in microspores subjected to a short cytochalasin D treatment, in the absence of a heat treatment. Cytochalasin D treatment of microspores resulted in dislocated mitotic spindles, disrupted phragmoplasts, and symmetric divisions and led to embryogenesis, confirming that a normal actin cytoskeleton has a role in preventing the induction of embryogenesis.
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 43 (2000), S. 179-188 
    ISSN: 1573-5028
    Schlagwort(e): DNA methylation ; mutagenesis ; somaclonal variation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Somaclonal variation is manifested as cytological abnormalities, frequent qualitative and quantitative phenotypic mutation, sequence change, and gene activation and silencing. Activation of quiescent transposable elements and retrotransposons indicate that epigenetic changes occur through the culture process. Epigenetic activation of DNA elements further suggests that epigenetic changes may also be involved in cytogenetic instability through modification of heterochromatin, and as a basis of phenotypic variation through the modulation of gene function. The observation that DNA methylation patterns are highly variable among regenerated plants and their progeny provides evidence that DNA modifications are less stable in culture than in seed-grown plants. Future research will determine the relative importance of epigenetic versus sequence or chromosome variation in conditioning somaclonal variation in plants.
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  • 21
    ISSN: 1573-5060
    Schlagwort(e): aluminium toxicity ; soil acidity ; somaclonal variation ; sorghum ; Sorghum bicolor (L.) Moench ; tissue culture ; salt stress ; drought stress ; variants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Sorghum bicolor (L.) Moench is generally quite sensitive to salt and acid (high aluminium) soil stresses, but quite tolerant of drought stress. As with any stress phenomenon, intra-specific variability exists within the genus. In vitro cell selection and somaclonal variation offer an alternative to traditional breeding methodology for generating improved breeding lines for hybrid development. A field selection protocol was developed for the three soil stresses and inter-stress evaluations were conducted in an effort to find multiple, stress-tolerant genotypes. The acid soil-drought stress, super-tolerant selections were located by the R7 generation when exposed to a combined aluminium-drought stress field environment and when the regeneration population (number of regenerated lines from one callus source) was maintained at 15,000 plants or higher. A variant frequency of 0.1 to 0.2% for stress tolerance and acceptable agronomic traits among the surviving somaclones, provided an adequate number of phenotypes with desirable agronomic characteristics and a high level of soil stress tolerance. Subsequent research verified that the stress-tolerant regenerants had superior acid soil and drought stress tolerance to that of the donor parents, that their yield capabilities under stress were superior to their parents, and that their stress tolerance attributes were transferred in hybrid combinations. In vitro selection was not effective in increasing the number of field stress survivors. In fact, superior germplasms were developed from non-stressed callus or salt-stressed callus. In vitro selection reduced regeneration frequency and subsequent survival of plants under field stress. In vitro-stressed regenerants should be subjected only to non-stressed environments to maintain population numbers for field selection and thereafter should be subjected to stress environments during later (R5+) generations. The optimal strategy for the exploitation of somaclonal variation may be through short-term cell culture (〈 12 months) with no attempt at in vitro selection.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 85 (1955), S. 335-339 
    ISSN: 1573-5060
    Schlagwort(e): callus culture ; organogenesis ; pea ; Pisum sativum ; somaclonal variation ; somatic embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The possibility of producing agronomically-useful somaclones via organogenesis and somatic embryogenesis from callus cultures of pea (Pisum sativum L.) was studied. Organogenic calli were induced from immature leaflets on MSB medium with NAA and BAP. Embryogenic calli were derived either from immature zygotic embryos (using 2,4-D) or from shoot apices (using picloram) of aseptically-germinated seedlings. The seed progenies (T1 to T3-generation) of primary regenerants were grown in field conditions and their phenotypic variation was evaluated and compared with control, non-tissue culture-derived plant material. In addition, electrophoretic analyses of selected isoenzyme systems and total proteins have been done. The results do not show dramatic changes in qualitative and quantitative traits. The evaluation of at least two future generations (T4, T5) is planned.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 85 (1955), S. 323-327 
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; fatty acids ; gas chromatography ; Lunaria annua ; protoplast regeneration ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A programme of research was designed to investigate methods for the modification of the fatty acid profiles of high performance lines of oilseed rape (Brassica napus L.) in an attempt to produce lines with enhanced levels of industrially useful fatty acids. The methodology employed to achieve these objectives was based on the exploitation of somaclonal or protoclonal variation, and targeted somatic hybridization using wild cruciferous germplasm as fusion partners. A range of somaclonal lines was produced from shoot regeneration protocols. These lines underwent replicated, randomised glasshouse trials for morphological assessment followed by gas chromatographic analysis to monitor any changes in fatty acid profile. It was found that a small number of lines exhibited potentially useful changes in oleic acid and polyunsaturated fatty acid content. Protoplast regeneration and electrofusion protocols for a range of winter oilseed rape lines were developed, and methods for the isolation and fusion of protoplasts of the wild crucifer Lunaria annua (chosen for its high nervonic acid content) established.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1573-5060
    Schlagwort(e): Linum usitatissimum ; linseed ; mutation breeding ; somaclonal variation ; fatty acids ; genetic engineering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In the early 1980s the phenomenon of somaclonal variation induced by cell culture was exploited to produce genetic variation in linseed. The linseed variety Andro, derived from the widely grown Canadian variety McGregor, was selected in saline culture and was released for production in Canada. ‘Andro’ possesses traits very different from its parent, such as increased seedling vigour and tolerance to heat stress. Additional stable somaclonal variation in characters such as yield, days to maturity, seed weight and oil content were subsequently induced in ‘McGregor’. However, despite extensive screening of the somaclonal variants, no significant variation in the fatty acid profile was found. Chemical mutagenesis using ethyl methanesulphonate was, however, succesful in modifying the fatty acid profile of McGregor. Initial screening of M2 seed by the thiobarbituric acid colourimetric procedure was followed by gas chromatography to select half-seeds with atypical fatty acid profiles. Two independent, partially dominant genes were identified that were responsible for reducing the linolenic acid (18 : 3) from 50% to 2% while increasing linoleic acid (18 : 2) to 70%. A single, partially dominant gene, inherited independently of the linolenic acid genes, increased palmitic acid (16 : 0) from 7% to 30% and palmitoleic acid (16 : 1) from trace amounts to 4%. Agrobacterium-mediated transformation of linseed has also been successful. Herbicide tolerance genes for glyphosate, sulfonylurea and phosphinothricin have been incorporated into Canadian varieties. Commercially useful levels of tolerance to sulfonylurea herbicides have been achieved with no adverse agronomic affect. It is expected that a transgenic variety containing this resistance will be registered for commercial production in Canada in 1994. Standard breeding techniques, the application of antisense technology and the overexpression of fatty acid synthesis genes are being used to further modify the fatty acid profile of linseed, as well as for the transfer of abiotic stress-related genes identified in bromegrass.
    Materialart: Digitale Medien
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  • 25
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium ; Brassica napus ; CaMV 35S promoter ; mas promoter ; gene expression ; risk assessment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Gene fusions between the β-glucuronidase (GUS) reporter gene and the promoters of the cauliflower mosaic virus 35S RNA transcript (CaMV 35S) and the mannopine synthase (mas) genes were introduced into rapeseed varieties via Agrobacterium-mediated transformation. Fluorometric assay of β-glucuronidase activity indicated different expression patterns for the two promoters. In seedlings, the CaMV 35S promoter had maximum activity in the primary roots, while the mas promoter was most active in the cotyledons. Etiolated seedlings cultured in the dark showed reduced activity of the mas promoter. Before vernalization at the rosette stage, both promoters were more active in older plant parts than in younger ones. At this stage the highest activity was recorded in cotyledons. After the plants had bolted reduced promoter function was detected in the upper parts of the transformed plants. Both promoters were found to be functional in the majority of the studied organs of transgenic rapeseed plants, but the promoter activity varied considerably between the organs at different developmental stages. The ability of pollen to transfer the introduced genes to other varieties and related species (e.g. Brassica napus and Diplotaxus muralis) by cross-pollination was studied in greenhouse experiments, and field trials were carried out to estimate the distance for biologically-relevant gene dispersal. In artificial crossing, the introduced marker gene was transferable into other varieties of Brassica napus. In field trials, at a distance of 1 metre from the source of transgenic plants, the frequency of an outcrossing event was relatively high (10-3). Resistant individuals were found at 16 and 32 metres from the transgenic pollen donors, but the frequency of an outcrossing event dropped to 10-5.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1573-5060
    Schlagwort(e): Brassica napus ; disease tolerance ; oxalic acid ; oxalate oxidase ; Sclerotinia sclerotiorum ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Oxalic acid is thought to have a primary role in the pathogenicity of several plant pathogens, notably Sclerotinia selerotiorum. A gene coding for the enzyme oxalate oxidase was isolated from barley roots and introduced into oilseed rape as a means of degrading oxalic acid in vivo. This report describes the production of several transgenic plants of oilseed rape and the characterisation of these plants by Southern, Western and enzyme activity assays. Plants were shown to contain an active oxalate oxidase enzyme and were tolerant of exogenously supplied oxalic acid.
    Materialart: Digitale Medien
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  • 27
    ISSN: 1573-5060
    Schlagwort(e): asymmetric somatic hybridization ; Brassica napus ; Brassica nigra ; disease resistance transfer ; dot blot analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Asymmetric somatic hybrid plants between Brassica napus L. (oilseed rape genome AACC) and a transgenic line of Brassica nigra L. Koch (black mustard genome BB) were tested for their resistance against rapeseed pathogens Phoma lingam (black leg disease) and Plasmodiophora brassicae (club root disease). The transgenic B. nigra line used (hygromycin-resistant, donor) is highly resistant to both fungi, whereas B. napus (recipient) is highly susceptible. The asymmetric somatic hybrids were produced using the donor-recipient fusion method (with X-irradiation of donor protoplasts) reported by Zelcer et al. (1978) for the production of cybrids. Using hygromycin-B for selection, a total of 332 hybrid calli were obtained. Regenerants, resistant or susceptible to both diseases, were selected. Many hybrids expressed resistance to only one pathogen. Dot blot experiments showed that the asymmetric hybrid plants contained varying amounts of the donor genomic DNA. Furthermore, a correlation was detected between the radiation dose and the degree of donor DNA elimination.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 85 (1955), S. 295-302 
    ISSN: 1573-5060
    Schlagwort(e): tissue culture ; somaclonal variation ; plant breeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Somaclonal variation is a tool that can be used by plant breeders. The review examines where this tool can be applied most effectively and the factors that limit or improve its chances of success. The main factors that influence the variation generated from tissue culture are (1) the degree of departure from organised growth, (2) the genotype, (3) growth regulators and (4) tissue source. Despite an increasing understanding of how these factors work it is still not possible to predict the outcome of a somaclonal breeding programme. New varieties have been produced by somaclonal variation, but in a large number of cases improved variants have not been selected because (1) the variation was all negative, (2) positive changes were also altered in negative ways, (3) the changes were not novel, or (4) the changes were not stable after selfing or crossing. Somaclonal variation is cheaper than other methods of genetic manipulation. At the present time, it is also more universally applicable and does not require ‘containment’ procedures. It has been most successful in crops with limited genetic systems and/or narrow genetic bases, where it can provide a rapid source of variability for crop improvement.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 85 (1955), S. 303-315 
    ISSN: 1573-5060
    Schlagwort(e): doubled haploids ; micropropagation ; mutant cultivars ; mutation techniques ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Conventional mutation techniques have often been used to improve yield, quality, disease and pest resistance in crops, or to increase the attractiveness of flowers and ornamental plants. More than 1700 mutant varieties involving 154 plant species have been officially released. In some economically important crops, e.g. barley, durum wheat and cotton, mutant varieties occupy the majority of cultivated areas in many countries. Mutation techniques have become one of the major tools in the breeding of ornamentals such as alstroemeria, begonia, chrysanthemum, carnation, dahlia and streptocarpus. The use of in vitro techniques such as anther culture, shoot organogenesis, somatic embryogenesis and protoplast fusion can overcome some of the limitations in the application of mutation techniques in both seed and vegetatively propagated crops. In vitro culture in combination with induced mutations can speed up breeding programmes, from the generation of variability, through selection, to multiplication of the desired genotypes. The expression of induced mutations in the pure homozygote obtained through microspore, anther or ovary culture, can enhance the rapid recovery of the desired traits. In some vegetatively propagated species, mutations in combination with in vitro culture technique, may be the only method of improving an existing cultivar. Currently, many molecular studies rely on the induction and identification of mutants in ‘model species’ for construction and subsequent saturation of genetic maps, understanding of developmental genetics and elucidation of biochemical pathways. Once identified and isolated, the genes that encode agronomically-important features can be either introduced directly into crop plants or used as probes to search for similar genes in crop species. It seems most likely that the recent developments based on these technologies will soon provide improved methods for selection of desired mutants.
    Materialart: Digitale Medien
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