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  • 1
    ISSN: 1871-4528
    Keywords: epigenetic variation ; leaf ontogeny ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato leaf morphology changes during plant development with the phase shift from vegetative growth to flowering. Image analysis can detect differences in leaf morphology and has been used here to distinguish differences in leaf morphology between potato crops derived from seed tubers and minitubers and between crops derived from different micropropagation protocols. Further, leaf shape parameters can be used to determine the relative maturity of crops. This finding is of economic importance since differences in plant development, for example delayed flowering, are associated with yield parameters. It is hypothesised that image analysis of established microplants can be used as an early evaluation of micropropagation protocols for potato.
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  • 2
    ISSN: 1573-9368
    Keywords: Bacillus thuringiensis ; Borer disease ; Saccharum ; somaclonal variation ; transgenic sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A population of 42 transgenic sugarcane ( hybrid, cv. Ja60‐5) clones expressing a truncated cryIA(b) gene from Bacillus thuringiensis was evaluated in field trials under artificial borer (Diatraea saccharalis Fab.) infection. Five clones displaying the highest borer tolerance were selected and analysed with molecular tools (RAPD, AFLP and RAMP) to verify genomic changes. Results of field trials provided evidence both for the expression of the resistance trait and for the occurrence of limited but consistent morphological, physiological and phytopathological variation, as compared with control plants regenerated from dedifferentiated culture without transformation (C1‐control) or with plants that were clonally propagated in the field (C2‐control). The five elite transgenic clones, selected for consistent borer‐resistance and good agronomic traits, were further evaluated in a large scale field trial. It was found that the majority of agronomic and industrial traits were those of the original cv. Ja60‐5, but that a small number of qualitative traits was different. DNA changes were verified in the five selected clones. A total of 51 polymorphic DNA bands (out of the 1237 analysed bands) was identified by extensive AFLP and RAMP analysis, thus showing rare but consistent genomic changes in the transgenic plants, as compared with C1‐ and C2‐control plants. It is proposed that the increased variability verified in transgenic plants by field trials and DNA analysis is essentially correlated with cell growth in the dedifferentiated state during the transformation procedure. The results, which are consistent with those published in the case of other transgenic plant populations, are discussed in the context of selecting approaches to gene transfer that minimize somaclonal variation. This is important especially in cases, such as that of sugarcane, where success of backcrosses to restore the original genotype is made difficult by the complex ploidy state of the plant.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 58 (1999), S. 159-162 
    ISSN: 1573-5044
    Keywords: agronomic traits ; Pennisetum glaucum ; Sclerospora graminicola ; somaclonal variation ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants regenerated from seed-derived callus of a PNMS 6B line of pearl millet (Pennisetum glaucum (L.) R. Br.) were evaluated for their resistance induced by somaclonal variation for downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroter. Among the 201 lines regenerated, only 3 lines consistently proved highly resistant (free from disease incidence) for up to 5 generations; whereas, 17 lines were resistant (disease incidence ranging from 1 to 9%). Resistance was confirmed by testing the plants under both laboratory and field conditions. The plants were evaluated for their agronomic traits.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 58 (1999), S. 199-203 
    ISSN: 1573-5044
    Keywords: triploid watermelon ; seedless watermelon ; tetraploid watermelon ; plant breeding ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ploidy of watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai shoots and plantlets was estimated by painting the lower epidermis of intact in vitro-derived leaves with fluorescein diacetate (FDA) and observing fluorescence of guard cell chloroplasts with a microscope and UV light. Leaves from in vitro shoot-tip cultures of known diploid cultivars and tetraploid breeding lines were used to establish the mean number of chloroplasts per guard cell pair. Leaves from diploid and tetraploid shoot cultures had 9.7 and 17.8 chloroplasts per guard cell pair, respectively. This method then was used to estimate the ploidy of shoots regenerated from cotyledon explants of the diploid cultivar Minilee. Approximately 11% of the 188 regenerated shoots were classified as tetraploid during in vitro culture. Putative tetraploids were transplanted to the field and self-pollinated. About 45% of tetraploids identified in vitro produced fruit and viable seed. Chloroplast counts of R1 progeny were used to confirm their ploidy. All of the putative diploids were confirmed diploid and all putative tetraploids proved to be non-chimeric true breeding tetraploids.
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  • 5
    ISSN: 1573-5060
    Keywords: Erwinia carotovora ; Solanum tuberosum ; somaclonal variation ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three somatic hybrid lines between potato (cv. While Lady line no. Ke 79, 2n = 2x = 48) + Solanum brevidens (PI 218228, 2n = 2x = 24) were evaluated using randomly amplified polymorphic DNA (RAPD) markers. The lines originated from the same callus but showed different reactions to Erwinia carotovora ssp. carotovora, the cause of potato soft rot. By the use of 48 oligomer primers producing 99 scorable bands, DNA polymorphism were detected on 7 of 12 S. brevidens chromosomes. Loss of certain DNA segments on chromosome 5, 6, 9 and 11 were observed. Some of the variations could have taken place in early callus stage of development; others may have occurred after initiation of individual shoot regeneration. The possible involvement of missing RAPD products specific to one somatic hybrid that shows decreased resistance to bacterial soft rot is discussed.
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  • 6
    ISSN: 1573-5044
    Keywords: Na+ tolerance ; plant regeneration ; salt stress ; Solanum tuberosum ; somaclonal variation ; RAPDs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A stable salt-tolerant potato cell line, able to grow on media containing 60–450 mM NaCl (i.e. low to high salinity) was selected. Callus grown on 120 or 150 mM NaCl showed higher fresh weights than the rest of the treatments. Replacing NaCl by KCl or Na2SO4 showed that reductions in fresh weight were mainly due to the presence of Na+ ions. When PEG 6000 was added to the medium instead of salt, the salt tolerant cell lines were unable to overcome the PEG-induced water stress. Whole plants, regenerated from salt tolerant callus, exhibited salt stress tolerance as evidenced by their higher fresh and dry weights when watered with 90 mM NaCl, and they also produced more tubers per plant under salt stress. Salt-tolerant plants differed phenotypically from control plants both in terms of leaf shape, tuber flesh and skin colour, which was reddish. In addition, DNA fingerprinting by RAPDs, with 70 different primers, confirmed that the salt tolerant regenerants also differed genotypically from the control, salt sensitive Kennebec potato plants from which they had been selected.
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  • 7
    ISSN: 1573-5060
    Keywords: Cucumis sativus L. ; rDNA ; regeneration systems ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Somaclonal variation in the Borszczagowski line of Cucumis sativus L. was determined for five regeneration systems: micropropagation (MP), direct leaf callus regeneration (DLR), leaf callus regeneration (LCR), recurrent leaf callus regeneration (RLCR), and direct protoplast regeneration (DPR). The frequency at which new phenotypes appeared in R1 lines and the stability of the rDNA region analysed using of five probes were investigated. MP was not subject to change, while DLR caused only infrequent changes. The highest frequency of change arose through DPR (90% of lines) and RLCR (42.8%), as opposed to 5.9% with LCR. Tetraploids were produced only in the case of LCR (4.7%) and RLCR (28%).
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  • 8
    ISSN: 1573-5060
    Keywords: Tissue culture ; somaclonal variation ; Triticum aestivum L. ; plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Somaclones (R3 and R4 generations) regenerated from five winter wheat (Triticum aestivum L.) genotypes were evaluated for variation in agronomic and morphological characters. Immature embryos were used as initial explant material. Comparisons for plant height, top internode length, spike length, number of seeds per spike and 100 seed weight were made between the somaclones and their parents. Some morphological variations of stem and spike characteristics were registered which demonstrate that plant height and spike length can be changed by using immature embryo culture. The results obtained may be considered a biotechnological contribution to wheat plant improvement.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 55 (1998), S. 151-154 
    ISSN: 1573-5044
    Keywords: protoplast ; somaclonal variation ; somatic embryo ; tissue culture ; Umbelliferae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hypocotyl segments of Bupleurum falcatum L. formed embryogenic calluses when cultured on Murashige and Skoog's (MS) medium supplemented with 9.0 μM 2,4-dichlorophenoxyacetic acid (2,4-D). Suspension cultures were initiated by placing calluses into medium with 0.45 μM 2,4-D. Protoplasts were enzymatically isolated from suspension cultures. They were plated at a density of 5 × 104 protoplasts per ml on MS medium supplemented with 9% mannitol, 9.0 μM 2,4-D, 4.4 μM BA, 4.6 μM kinetin, and 0.6% Seaplaque agarose. After four weeks of culture, microcalluses were formed and subsequently transferred to MS solid medium with 18.1 μM 2,4-D. Upon transfer to MS basal medium, microcalluses gave rise to somatic embryos at a frequency of approximately 10%. They subsequently developed into plantlets. The regenerants were successfully transplanted to potting soil and grown to maturity in a greenhouse. The regenerants had the normal chromosome number of 2n=2x=20 and did not show morphological aberrancy.
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  • 10
    ISSN: 1573-5087
    Keywords: chilling tolerance ; fatty acids ; galactolipids ; phospholipids ; rice ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between chilling tolerance of six rice cultivars – Facagro 57, Facagro 76, Fujisaka 5, Kirundo 3, Kirundo 9 and IR64 -and the fatty acid composition in total lipids, phospholipids, galactolipids and neutral lipids from leaves was studied. Higher double bond index and proportions of linolenic acid in the phospholipid and galactolipid classes were related to cultivar chilling tolerance, but this was not so for the total lipids nor the neutral lipid class. The somaclonal families derived from Facagro 76, Kirundo 3 and Kirundo 9 that showed enhanced chilling tolerance as compared to their original parental cultivar were analyzed for fatty acid composition in phospholipids and galactolipids from leaves. Altered proportions in fatty acid composition in phospholipids, galactolipids or both were found in the somaclonal families derived from Facagro 76 and Kirundo 9, but not from Kirundo 3. These changes most usually resulted in higher double bond index and higher proportions in linoleic and linolenic acids which were related either to lower ratio of C16 to C18 fatty acids or to higher unsaturation in the C18 fatty acid fraction. Different mechanisms thus seem to be implicated in the altered fatty acid composition of somaclones, which may be related to the chilling tolerance improvement of some somaclonal families.
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  • 11
    ISSN: 1573-5060
    Keywords: Malus ; somaclonal variation ; tissue culture ; in vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To assess somaclonal variation, ‘Gala’ and ‘Royal Gala’ trees obtained via axillary and adventitious bud formation were compared ex vitro to conventionally grafted trees. In general, tissue culture-derived trees were relatively erect in comparison to grafted trees. Their branch angles were narrower than those of grafted trees. All trees that flowered had pink blossoms. There were no obvious differences in flowering time or in floral morphology. Most of the seven-year-old grafted control trees produced more fruits than either axillary or regenerated trees. Although there were differences in the range of fruit color between ‘Royal Gala’ and ‘Gala’ apples in both the control and tissue culture-derived plants (the fruits of ‘Royal Gala’ were darker red and more striped than those of ‘Gala’) and also in the degree of pigmentation from tree-to-tree, none of the variation exceeded that observed among apples harvested from an individual ‘Royal Gala’ or ‘Gala’ control tree for either the plants derived from axillary buds or adventitiously. Since both ‘Gala’ and ‘Royal Gala’ axillary buds showed very little somaclonal variation for the morphological and reproductive traits we studied, it appears that tissue culture may be a useful way to propagate these cultivars.
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  • 12
    ISSN: 1573-5060
    Keywords: apple ; fire blight ; resistance ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four somaclonal variants regenerated from adventitious buds of the apple variety Greensleeves were preselected on the basis of their reduced fire blight susceptibility. The present study aimed at assessing precisely their level of fire blight resistance through various inoculation techniques (on in vitro leaves and microcuttings, on greenhouse plants and in field conditions). Overall results of these tests indicated that one clone (R 46/3) was clearly less susceptible than the control. This clone was also characterized as a ‘spur’ variant, with a reduced growth which can explain its limited susceptibility to fire blight. A second clone (R 20/63) was slightly less susceptible than the control in greenhouse and field tests, but this low level of resistance was overcome by high concentrations of inoculum. The absence of variation in chromosome number and isozyme patterns confirmed the genetic trueness-to-type of these four somaclones.
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  • 13
    ISSN: 1432-203X
    Keywords: Oryza sativa ; rice ; somaclonal variation ; genetic integrity ; RAPD analysis ; DNA markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary RAPD analysis was performed among eight rice somaclonal families known to vary for specific characters and four somaclonal families which were phenotypically normal. The parental cultivar,indica rice cv. FR13A, was found to be homogeneous and homozygous at all but one of the 45 RAPD loci. Polymorphisms were found at 28 of the 45 bands among the somaclonal families, including both loss of parental bands, and the appearance of novel non-parental bands. Segregation data revealed both heterozygous and homozygous mutation events, with recessive mutations more prevalent than dominant. All somaclonal families differed significantly from the parental material, indicating that genomic alterations occurred in all families regardless of phenotype. None of the variant families could be regarded as isogenic lines of FR13A at the DNA level. However, some of the DNA level variation may be in highly repeated sequences with no phenotypic effects. The implications for somaclonal breeding and genetic engineering programs are discussed.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Biochemical genetics 35 (1997), S. 189-204 
    ISSN: 1573-4927
    Keywords: somaclonal variation ; tissue culture ; isozymes ; cactus ; genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Morphological and isozyme variation was observed among plants regenerated from callus cultures of Cereus peruvianus. Different morphological types of shoots (68%) were observed in 4-year-old regenerated plants, while no distinct morphological variants were observed in plants grown from germinated seeds. Isozyme patterns of 633 plants regenerated from calli and of 261 plants grown from germinated seeds showed no variation in isocitrate dehydrogenase isozyme, and the differential sorbitol dehydrogenase, alcohol dehydrogenase, malate dehydrogenase, acid phosphatase, and peroxidase isozyme patterns observed in regenerated plants were attributed to nonallelic variation. Allelic variation was detected at three isoesterase loci. The proportion of polymorphic loci for both populations was 13.6% and the deviation from Hardy–Weinberg equilibrium for the Est-1 and Est-7 loci observed in somaclones was attributed to the manner in which the regenerant population was established. The high values for genetic identity among regenerant and seed-grown plant populations are in accordance with the low levels of interpopulation genetic divergence. In somaclones of C. peruvianus, morphological divergence was achieved within a short time but was not associated with any isozyme changes and also was not accompanied by biochemical genetic divergence.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 35 (1997), S. 231-240 
    ISSN: 1573-5028
    Keywords: insertion mutation ; retrotransposon ; rice ; somaclonal variation ; transposable elements ; transposon tagging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Retrotransposons were extensively surveyed in rice using two molecular methods. The total copy number of retrotransposons in the rice genome was estimated to be about 1000 and 32 families were isolated, showing that retrotransposons are a major class of transposable elements in rice. Although these retrotransposons appear inactive during normal growth conditions, 5 out of 32 families were active under tissue culture conditions. The most active element, Tos17, was studied in detail. Its activity was show to be regulated mainly at the transcriptional level. The analysis of target sites of transposition indicated that activation of Tos17 is an important cause of tissue culture-induced mutations in rice. Tissue culture-induced activation of Tos17 was used to develop the site-selected mutagenesis system, in which mutants carrying a Tos17 insertion in the gene of interest can be identified among rice plants regenerated from tissue culture by the PCR using one primer for the ends of Tos17 and another for the gene of interest. This system will contribute to understanding the functions of rice genes whose sequences are being determined by the rice genome project.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 95 (1997), S. 229-235 
    ISSN: 1573-5060
    Keywords: apomixis ; Hypericum perforatum ; rDNA ; heterogeneity ; RFLP ; progeny ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three adjacent EcoRI fragments of the rDNA unit from Lycopersicon esculentum, eleven anonymous genomic and two anonymous cDNA clones from Brassica napus and three restriction endonucleases: BamHI, EcoRI and EcoRV were used for RFLP analysis of the genome of Hypericum perforatum L. A polymorphic band identified with EcoRI and two rDNA probes in five somaclones originated from the same genotype was detected in all progenies of two somaclones indicating the inheritance of the molecular changes. rDNA unit heterogeneity represented by two types of RFLP pattern revealed among somaclones and seed-derived control plants using EcoRV and two rDNA probes may indicate an alloploid origin of Hypericum perforatum. The occurrence of the identical RFLP patterns in some R0 somaclones and seed-derived plants and their progenies may be related to the apomictic mode of reproduction which is assumed to be prevalent in Hypericum perforatum. The differences in RFLP patterns of progenies when compared with the maternal plants (1 out of 10 progenies of one control plant and 1 out of 8 progenies of one somaclone) may indicate that some progenies have originated through sexual recombination.
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  • 17
    ISSN: 1573-5060
    Keywords: Sweet potato ; Ipomoea batatas ; plant regeneration ; somatic embryogenesis ; protoplasts ; genetic variation ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The application of new techniques for improvement of sweet potato crops, particularly including the exploitation of somaclonal variation, gene transfer by genetic transformation and somatic hybridization, requires the control of plant regeneration from tissue cultures. Shoots can easily be regenerated from explants of stems, petioles, leaves and roots, while callus cultures do not produce any shoots. The potential of somatic embryogenesis and plant regeneration via embryogenesis was evaluated for 10 cultivars of sweet potato. Protocols for plant regeneration from cultured protoplasts have also been developed. Since mesophyll was resistant to enzyme digestion, fragments of stems and petioles, callus and cell suspensions were used as source of protoplasts of sweet potato. Series of transfers of protoplast-derived calluses, particularly those which had been obtained from in vitro plants, to media containing a high level of zeatin resulted in successful formation of shoots in only two sweet potato cultivars. In addition, the embryogenic potential was irreversibly lost through protoplast culture, since protoplasts isolated from embryogenic cell suspensions developed into non-embryogenic callus. Consequently, an alternative protocol is being successfully developed to improve plant regeneration from cultured protoplasts of sweet potato, involving first root formation from which shoots can then be regenerated. Preliminary evaluation in field conditions in Gabon revealed that plants regenerated from cultured protoplasts exhibited a great genetic variability in their growth and tuber formation in particular.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 96 (1997), S. 135-142 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; chilling tolerance ; in vitro selection ; rice ; somaclonal variation ; field performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Embryo-derived calli of four rice varieties cultivated at high altitude in Burundi — Facagro 57, Facagro 76, Kirundo 3 and Kirundo 9 — were submitted to different temperature regimes. The percentage of regenerating calli greatly varied depending on variety, length of culture and callus temperature treatment. The reduction of regeneration percentages induced by low temperature was more pronounced in the more sensitive varieties. Regenerated plants (R0) and their progenies in R1, R2 and R3 were cold-screened together with control plants. In all varieties, significantly higher survival rates were obtained in R3 with in vitro plants than with control plants. Such chilling tolerance improvement was not obtained following a massal selection applied during 3 successive generations onto the control plants. In vitro plants regenerated from calli cultivated either at 25 °C, either at 4 °C, were cultivated at different altitudes in Burundi during two successive generations. For most observed traits, the in vitro plants were characterized by lower means, larger variation and higher maximum values than the control plants. The most chilling-tolerant somaclonal families were most usually characterized by extensive differences in fatty acid composition, chilling-induced electrolyte leakage and chlorophyll fluorescence, compared to the varieties they derived from.
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  • 19
    ISSN: 1573-5060
    Keywords: somaclonal variation ; in vitro selection ; herbicides ; wheat ; triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present work was initiated to assess tissue culture techniques as a means of generating and selecting herbicide tolerant genotypes of wheat through exploiting somaclonal variation. Callus was initiated from immature embryos of genetically defined varieties and subcultured onto selective media containing 5 μm, 10 μm and 50 μm concentrations of difenzoquat and atrazine. Plants were regenerated from all the selective media except that media containing the highest herbicide concentration. The progenies of the regenerated plants were tested as whole plants for their response to spray application of the herbicides. For difenzoquat, variation in response from extreme susceptibility to tolerance was observed. However, genetic characterization by progeny testing tolerant lines revealed that the induced variation was not heritable. No plants tolerant to atrazine were obtained. Overall, no clear evidence of heritable mutations was obtained. Alternative strategies to obtain herbicide tolerant genotypes using cell culture techniques are discussed.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 48 (1997), S. 31-35 
    ISSN: 1573-5044
    Keywords: Cucurbitaceae ; Cucumis melo ; polyploidy ; regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosome number of cells in the shoot primordium aggregates and produced plants of melon [Cucumis melo L. 'Prince' (2n=2x=24)] was examined. Shoot primordium aggregates were induced from shoot-tips cultured in liquid medium and shaken at low speed (2 rpm). They were maintained by subculturing small pieces (5mm〈) every 4 weeks. Shoot primordium aggregates just after induction contained about 97 diploid and 3 tetraploid cells, which was similar to those maintained in shoot primordium cultures for 6 years. This indicates that the ploidy level was maintained stably. On the other hand, plants produced from the shoot primordium aggregates just after induction were either diploid, tetraploid or mixoploid with both diploid and tetraploid cells. These ploidies were again observed among plants produced from shoot primordium cultures that were 2, 3 or 4 years old. A majority of produced plants were diploid while the total frequency of tetraploids and mixoploids was less than 8 of plants produced from all ages. Therefore, the frequency of somaclonal variation with respect to ploidy among plants produced from shoot primordium aggregates is likely to be stable at a low level over the long term.
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  • 21
    ISSN: 1432-203X
    Keywords: Primulaceae ; tissue culture ; regeneration ; somaclonal variation ; organogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In long-term callus cultures of Cyclamen persicum Mill. two types of tissue could be distinguished. One type featured a brown suberised outer layer and was poorly organogenic. The other type was yellowish in appearance and gave rise to many shoot buds. Both types co-existed on the same callus, the former prevailing. Selection for organogenic tissue resulted in cultures yielding approximately three times more petioles than random subcultures. Callus-derived shoots could be rooted and established in the greenhouse. The method allowed for the production of thousands of plants but the regenerants often showed deviant phenotypes and genotypes.
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  • 22
    ISSN: 1573-9368
    Keywords: Transgenic rice ; PCR-RAPD ; arbitrary DNA primers ; genomic changes ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of genomic modifications in transgenic rice plants recovered from protoplasts and their transmission to the self-pollination progeny has been verfied with the random amplified polymorphic DNA (RAPD) approach. The plant was the Indica-type rice (Oryza sativa L.) cultivar Chinsurah Boro II. The analysed material was: (1) microspore-derived embryogenic rice cells grown in suspension culture, (2) transgenic plants recovered from protoplasts produced from the cultured cells and (3) the self-pollination progeny (two successive generations) of the transgenic plants. DNA purified from samples of these materials was PCR-amplified with different random oligonucleotide primers and the amplification products were analysed by agarose gel electrophoresis. Band polymorphism was scored and used in band-sharing analyses to produce a similarity matrix. Relationships among the analysed genomes were expressed in a dendrogram. The extensive DNA changes evidenced in cultured cells demonstrate the occurrence of somaclonal variation in the material used to produce protoplasts for gene transfer. Quantitatively reduced DNA changes were also found in the resulting transgenic plants and i their self-pollination progenies. While confirming the stability of the foreign gene in transgenic plants, this work gives molecular evidence for the occurrence of stable genomic changes in transgenic plants and points toin vitro cell culture as the causative agent. RAPDs are shown to be a convenient tool to detect and estimate the phenomenon at the molecular level. The methodology is also proposed as a fast tool to select those transgenic individuals that retain the most balanced genomic structure and to control the result of back-crosses planned to restore the original genome.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 46 (1996), S. 179-186 
    ISSN: 1573-5044
    Keywords: cereal ; herbicide-tolerance ; Hordeum vulgare ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro culture of barley calluses has been used to produce plants with increased glyphosate tolerance. Calluses from immature embryos of barleyHordeum vulgare L. (‘Jeff’) were cultured on Murashige and Skoog medium with 10-6, 10-5, 10-4, 5×10-4, 10-3, or 10-2M glyphosate for one, four or thirty months. Plants were regenerated from calluses maintained in glyphosate medium at 10-6, 10-5 or 10-4M for four months, at 10-5 or 5×10-4M for one month and at 10-5M for thirty months. The progeny of each regenerated plant was analyzed for response to glyphosate. Some progenies showed increased tolerance to glyphosate.
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  • 24
    ISSN: 1573-5060
    Keywords: Alstroemeria ; genetic fingerprinting ; RAPD ; somaclonal variation ; alstroemeria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We have used random amplified polymorphic DNA (RAPD) markers to study genetic variation in Alstroemeria. The first objective was to examine the discriminatory power of RAPD markers in different genotypes of Alstroemeria obtained by traditional breeding. All genotypes examined, including commercial Alstroemeria varieties, could be distinguished on the basis of their RAPD profiles. Progeny plants could be distinguished from their parents. A second objective of this study was to investigate whether RAPD markers can be used as a routine tool to detect mutant plants, as an alternative to glasshouse testing. To address this objective, we analysed Alstroemeria plants that carried phenotypically visible mutations that either were induced by irradiation using X-rays or were the result of somaclonal variation. In eight out of a total of 13 mutant Alstroemeria plants obtained after irradiation or tissue culture we detected no polymorphisms when compared to control plants that were considered to be non-mutated. Only in five of the mutant plants analysed we detected one to two polymorphisms. These results suggest that frequent genome rearrangements had not occurred in the mutant plants analysed. These results also demonstrate that the RAPD technique is an inappropriate tool for the rapid screening of Alstroemeria for induced variation. It that the RAPD technique is an inappropriate tool for the rapid screening of Alstroemeria for induced variation. It seems probable that this conclusion would be equally applicable in other plant genera in which induced variation has occurred. However, the RAPD technique is a simple and effective tool for genetic fingerprinting of Alstroemeria varieties, provided their differences are due to sexual propagation.
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  • 25
    ISSN: 1573-5060
    Keywords: Fusarium resistance ; Fusarium spp. ; wheat ; Triticum aestivum ; culture filtrate ; in vitro selection ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Calli of resistant, intermediary and susceptible wheat (Triticum aestivum L.) varieties were selected using culture filtrates of Fusarium graminearum and F. culmorum and the regenerants were evaluated for resistance up to R3. Czapek-Dox broth medium was inoculated with mycelia of Fusarium isolates and incubated for 2–6 weeks. Filtrates were added to MS callus growing medium, then 5 weeks-old calli were transferred onto this medium (MST) for 4–5 weeks. MST containing 30% filtrate was found to be suitable for selection. Resistant calli were transferred again to fresh MST for further two selection cycles. The surviving calli produced less fertile regenerated lines (R0) than the non-selected ones. Among 18 R1 lines tested for Fusarium-resistance in the seedling stage by artificial inoculation in the greenhouse, two (11.1%) were significantly more resistant, one (5.6%) was more susceptible than the original cultivar and the rest (83.3%) behaved similarly to the donor plants. Among unselected R3 lines of three varieties, practically the same number of resistant plants were found as among the related selected ones. When the R3 selfed generations obtained through double-layer and culture filtrate selection techniques were tested for Fusarium-resistance, 35.7% of the lines were found to be more resistant than the original cultivars, none was more susceptible and 64.3% had a reaction similar to that of the source materials. Thus, inheritance of the disease reaction was not stable in all cases. Success of in vitro selection for Fusarium-resistance depended also on the genotype, and toxin analysis showed that although being effective, the selective media contained deoxynivalenol only exceptionally. In selecting wheat for Fusarium-resistance in vitro, the culture filtrate technique proved better than the double-layer procedure.
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  • 26
    ISSN: 1432-203X
    Keywords: Cucumis mel ; somaclonal variation ; low-temperature ; selection ; germinability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants were regenerated from adventitious buds and somatic embryos (R0) of melon (Cucumis melo L.), the cultivar Andes. Somaclonal variants of melon with low temperature germinability were selected from the progenies (R1) of R0 plants. Among 5,618 R1 seeds harvested from 23 R0 plants that were regenerated from adventitious buds 4 seeds germinated after 5 days of culture at 15 °C (selection rate; 0.07%). However, among 374 R2 seeds harvested from 2 R1 plants no seed germinated after 7 days of culture at 14 °C. Among 9,181 R1 seeds harvested from 50 R0 plants regenerated from somatic embryos 110 seeds germinated after 5 days of culture at 15 °C (selection rate; 1.20%). Among 3,717 R2 seeds harvested from 17 R1 plants 113 seeds germinated after 7 days of culture at 14 °C (selection rate; 3.04%). R3 seeds were collected from these R2 plants following self-pollination. Forty-five of the 47 lines (R3) originated from 10 R0 plants showed higher germination rates than that of the original cultivar. Selected lines with low-temperature germinability showed greater fruit growth rate than the original cultivar during the middle stage when they were cultivated in a greenhouse under low-temperature conditions. Of fruits harvested from 31 lines, 15 lines showed greater fruit volume than the original cultivar.
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  • 27
    ISSN: 1573-5060
    Keywords: somaclonal variation ; somatic embryogenesis ; tissue culture ; wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Somatic embryogenesis was initiated from ‘immature embryos’ on Murashige-Skoog (MS) medium plus 2 mg.l-1 2,4-dichlorophenoxyacetic acid, 2% sucrose and 0.6% agarose. Somatic embryos were isolated and regenerated into whole green plants on MS medium devoid of 2,4-D. These regenerants were previously demonstrated to differ in their mitochondrial DNA organization. In order to estimate their characteristics three progenies of short-term culture regenerants and three progenies of long-term culture regenerants were analyzed and compared to the parental line. These somaclones obtained from the wheat variety Chinese Spring were evaluated for variation of 13 agronomic and morphological quantitative characters in comparison to the parental line. Significant variation was observed for plant height, spike length, main tiller diameter, between the somaclones regenerated from long-term culture and their parent. Differences were observed to increase with the duration of culture, leading to a significant modification of the structure of the plants. Several changes occurred during the somatic tissue cultures, but to a lesser extent than has previously been described in the literature.
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  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 43 (1995), S. 229-235 
    ISSN: 1573-5044
    Keywords: Albinism ; Hordeum vulgare L. ; somaclonal variation ; totipotency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The use of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-d) has played an important role in the production and maintenance of totipotent cereal callus. However, 2,4-d has been implicated in the loss of totipotency from barley callus. To examine the effect of 2,4-d on barley callus, regenerability and karyotype were examined over time as influenced by cultivar differences and 2,4-d levels, during a period in which initially vigorous plant regeneration typically declines dramatically. Higher (20.4–27.1 μM) versus lower (6.8–13.6 μM) concentrations of 2,4-d were positively associated with the number of green plantlets recovered from calli maintained for 10 and 16 weeks before transfer to regeneration media, and with the longevity of regenerability. There was a positive relationship between 2,4-d concentration and normal karyotype. We also investigated the use of phenylacetic acid for the initiation of regenerable barley callus. Very poor callus growth and plant regeneration was supported by phenylacetic acid.
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  • 29
    ISSN: 1573-5087
    Keywords: Gibberellin ; in vitro propagation ; Musa, quantification ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract GA3 and GA20 were quantified in leaf extracts from true-to-type and somaclonal variants (dwarf and giant) of Musa AAA cv. ‘Grand nain’ by GC-MS-SIM after purification on reverse- and normal-phase HPLC and detection by ELISA with GA3 antibodies and by a dwarf rice bioassay. GA3 concentration in dwarf plants was 811 ng g−1 dry weight. For normal and giant plants, the endogeneous GA3 levels were respectively 3.6 and 4.6 times higher. The GA20 concentration in the giant plant was 68 ng g−1 of dry weight. This concentration was, respectively, 4.6 and 7.3 times higher than those of normal and dwarf plants. These results suggest that the somaclonal variations affecting banana plant height are associated with modifications in GA metabolism.
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  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 41 (1995), S. 9-15 
    ISSN: 1573-5044
    Keywords: birdsfoot trefoil ; cotyledonous protoplasts ; Lotus corniculatus L. cv. Leo ; pretreatment ; regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method was developed for rapid plant regeneration from protoplasts of birdsfoot trefoil (Lotus corniculatus L. cv. Leo). Green cotyledons from in vitro grown seedlings were preplasmolyzed in CPW salts containing 13% mannitol (CPW 13 M) for 1 h prior to the enzyme treatment. The enzyme formula consisted of 2% (w/v) Onozuka Cellulase R-10, 1% (w/v) Macerase and 0.1% (w/v) Pectolyase Y-23 in CPW 13 M. This method produced high yields of viable protoplasts after purification. The procedure is reproducible and takes approximately 2.5 months from protoplast isolation to plantlet establishment in a greenhouse. More than 100 plantlets were grown in soil. Two somaclonal variants, a chimeric plant for chlorophyll production and an albino cell line, have been obtained by this procedure.
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  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 40 (1995), S. 187-189 
    ISSN: 1573-5044
    Keywords: propagation ; somaclonal variation ; triglycerides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant rgeneration occurred on leaf-and stem-derived callus of Cuphea ericoides Cham. & Schlechtd obtained in Murashige and Skoog medium supplemented with auxins [indole-3-acetic acid (IAA), α-naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-d)] plus cytokinins [6-benzyladenine (BA) or kinetin]. These calluses were subcultured and showed vigorous growth. When subcultured on medium containing 2.22 or 4.44 μM BA, the calluses showed profuse regeneration of shoots whereas those subcultured on medium supplemented with 2.69 μM NAA or 0.226 μM 2,4-d produced numerous roots. Isolated shoots rooted on Murashige and Skoog medium lacking growth regulators or containing 0.54 μM NAA or 0.49 μM indole-3-butyric acid (IBA). Plantlets were acclimatized to greenhouse conditions.
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  • 32
    ISSN: 1573-5060
    Keywords: glyphosate ; herbicide tolerance ; non-target effects ; somaclonal variation ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The progeny of 104 regenerated maize plants were screened for tolerance to the safe broad-spectrum herbicide glyphosate during seed germination and early growth. Seven somaclones showed varying degrees of resistance to the application of the herbicide at 1.2 mM (0.1 kg a.i. in 400 1 ha-1 of water). Plants capable of a normal growth following treatment with 2.4 mM (0.2 kg ha-1) glyphosate at the three leaf stage were selfed, and their progeny analyzed. A family able to tolerate the exposure to glyphosate at 2.4 mM was isolated and shown to maintain a photosynthetic rate comparable with control after the application of the herbicide. The selfed progeny of the tolerant somaclone was characterized as to the properties of two targets of glyphosate, the shikimate pathway enzymes 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase and 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase. In vitro tests ruled out the possibility that the tolerance was due to altered forms of these enzymes. Families showed significant variability with regard to EPSP and DAHP synthase levels, measured at different stages during seedling growth; however, not even these traits were correlated with in vivo response to glyphosate. The possible role of other physiological processes in determining the increased tolerance to the herbicide is discussed.
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  • 33
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 11 (1995), S. 416-425 
    ISSN: 1573-0972
    Keywords: Genetic transformation ; micropropagation ; somaclonal variation ; synthetic seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Many important food and fibre crops have attained close to their maximum yields as a result of conventional breeding approaches and advances in agronomic and horticultural practices. The manipulation of cell and tissue cultures to produce somatic embryos efficiently is one of the keystones of the new technologies that will greatly alter the way crops are planted (as synthetic seed) and genetically altered in the future. Gene transfer into embryogenic plant cells is already challenging conventional plant breeding, and has become an indispensable tool for crop improvement. This review provides a current assessment of the impact of somatic embryogenesis in agriculture.
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  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 85 (1955), S. 295-302 
    ISSN: 1573-5060
    Keywords: tissue culture ; somaclonal variation ; plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 35
    ISSN: 1573-5060
    Keywords: doubled haploids ; micropropagation ; mutant cultivars ; mutation techniques ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 36
    ISSN: 1573-5060
    Keywords: aluminium toxicity ; soil acidity ; somaclonal variation ; sorghum ; Sorghum bicolor (L.) Moench ; tissue culture ; salt stress ; drought stress ; variants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 37
    ISSN: 1573-5060
    Keywords: callus culture ; organogenesis ; pea ; Pisum sativum ; somaclonal variation ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 85 (1955), S. 323-327 
    ISSN: 1573-5060
    Keywords: Brassica napus ; fatty acids ; gas chromatography ; Lunaria annua ; protoplast regeneration ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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  • 39
    ISSN: 1573-5060
    Keywords: Linum usitatissimum ; linseed ; mutation breeding ; somaclonal variation ; fatty acids ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
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