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  • 1
    Electronic Resource
    Electronic Resource
    Expression of a cassava granule-bound starch synthase gene in the amylose-free potato only partially restores amylose content (1999)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Granule-bound starch synthase I (GBSS I) is responsible for the synthesis of amylose in starch granules. A heterologous cassava GBSS I gene was tested for its ability to restore amylose synthesis in amylose-free (amf) potato mutants. For this purpose, the cassava GBSS I was equipped with different transit peptides. In addition, a hybrid containing the potato transit peptide, the N-terminal 89 amino acids of the mature potato GBSS I, and the C-terminal part of cassava GBSS I was prepared. The transgenic starches were first analysed by iodine staining. Only with the hybrid could full phenotypic complementation of the amf mutation be achieved in 13% of the plants. Most transformants showed partial complementation, but interestingly the size of the blue core was similar in all granules derived from one tuber of a given plant. The amylose content was only partially restored, up to 60% of wild-type values or potato GBSS I-complemented plants; however, the GBSS activity in these granules was similar to that found in wild-type ones. From this, and the observation that the hybrid protein (a partial potato GBSS I look-alike) performs best, it was concluded that potato and cassava GBSS I have different intrinsic properties and that the cassava enzyme is not fully adapted to the potato situation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00493.x
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  • 2
    Electronic Resource
    Electronic Resource
    Successful first and second backcrosses of S. nigrum (+) S. tuberosum somatic hybrids with both Solanum parents (1999)
    Springer
    Sexual plant reproduction 12 (1999), S. 144-151 
    Details
    ISSN: 1432-2145
    Keywords: Key words Solanum tuberosum ; Solanum nigrum ; Somatic hybrids ; Backcross experiments ; Phytophthora infestans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Somatic hybrids of Solanum nigrum (+) 2× potato were successfully crossed with S. nigrum and with potato. First and second backcross progeny with S. nigrum could easily be obtained. One of the BC1 genotypes was already self-fertile. Backcrosses with potato had a much lower success rate. Only pollinations with tetraploid potato resulted in seed-containing berries. Two BC1 genotypes were obtained after 4362 pollinations from which 505 ovules were cultured. The first BC1 genotype grew vigorously in vitro and in the greenhouse and flowered abundantly. The second BC1 showed many abnormalities and dropped its flowers before anthesis. The first BC1 was again crossed with tetraploid potato and in this generation also the success rate was low. Over 5000 pollinations resulted in 1750 berries from which over 3000 ovules were obtained. Twelve plants germinated from these ovules and they were not as vigorous in vitro and in vivo as the BC1 parent. Some of the BC2 genotypes were used for further backcrosses but no BC3 plants were obtained. BC1 and BC2 genotypes that resulted from the backcross program with potato were tested for resistance to Phytophthora infestans. The BC1 genotype was as resistant as the S. nigrum fusion parent, but among the eight BC2 genotypes scored six were resistant, whereas two genotypes showing lesions were susceptible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050185
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  • 3
    Electronic Resource
    Electronic Resource
    The extent and position of homoeologous recombination in a distant hybrid of Alstroemeria: a molecular cytogenetic assessment of first generation backcross progenies (1999)
    Springer
    Chromosoma 108 (1999), S. 52-63 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract.  To estimate the extent and position of homoeologous recombination during meiosis in an interspecific hybrid between two distantly related Alstroemeria species, the chromosome constitution of six first generation backcross (BC1) plants was analysed using sequential fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH) analysis. Four different probes were used for the FISH analysis: two species-specific and two rDNA probes. The six BC1 plants were obtained from crosses between the hybrid A. aurea×A. inodora with its parent A. inodora. GISH clearly identified all chromosomes of both parental genomes as well as recombinant chromosomes. The sequential GISH and FISH analysis enabled the accurate identification of all individual chromosomes in the BC1 plants, resulting in the construction of detailed karyotypes of the plants. The identification of the recombinant chromosomes provided evidence which chromosomes of the two species are homoeologous. Two of the BC1 plants were aneuploid (2n=2x+1=17) and four triploid (2n=3x=24), indicating that both n and 2n gametes were functional in the F1 hybrid. Using GISH, it was possible to estimate homeologous recombination in two different types of gametes in the F1 hyrid. The positions of the crossover points ranged from highly proximal to distal and the maximum number of crossover points per chromosome arm was three. Compared with the aneuploid plants, the triploid plants (which received 2n gametes) clearly possessed fewer crossovers per chromosome, indicating reduced chromosome pairing/recombination prior to the formation of the 2n gametes. Besides homeologous recombination, evidence was found for the presence of structural rearrangements (inversion and translocation) between the chromosomes of the parental species. The presence of the ancient translocation was confirmed through FISH analysis of mitotic and meiotic chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050351
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  • 4
    Electronic Resource
    Electronic Resource
    GBSS T-DNA inserts giving partial complementation of the amylose-free potato mutant can also cause co-suppression of the endogenous GBSS gene in a wild-type background (1996)
    Springer
    Plant molecular biology 31 (1996), S. 731-739 
    Details
    ISSN: 1573-5028
    Keywords: complementation ; expression ; co-suppression ; granule-bound starch synthase ; Solanum tubersoum L. ; transgenic inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The wild-type gene encoding granule-bound starch synthase (GBSS) is capable of both complementing the amylosefree (amf) potato mutant and inhibiting the endogenous GBSS gene expression in wild-type potato. Co-suppression of the endogenous GBSS gene, easily visualised by staining the starch with iodine, occurred when the full-size GBSS sequence (genomic), GBSS cDNA or even the mutant amf allele were introduced into the wild-type potato. Conversely, introduction of the GBSS promoter sequence alone, did not result in co-suppression in the 80 analysed transformants. Neither the orientation of the GBSS gene with respect to kanamycin resistance nor the presence of an enhancer influenced the frequency of plants showing a co-suppression phenotype. After crossing a partially complemented amf mutant with a homozygous wild-type plant, the F1 offspring segregated into plant phenotypes with normal and decreased expression of the GBSS gene. This decreased expression correlated with the presence of a linked block of five T-DNA inserts which was previously shown to be correlated with partial complementation of the amf mutant. This crossing experiment indicates that co-suppression can cause inhibition of gene expression of both inserted and endogenous wild-type GBSS genes. The frequency of partially complemented amf plants was equal to the frequency of co-suppressed wild types when a construct, with an enhancer in front of the GBSS promoter, was used (pWAM 101E). This might suggest that partial complementation of the amf genotype caused by unstable expression of the transgene can be overcome by inserting an enhancer in front of the GBSS promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019461
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  • 5
    Electronic Resource
    Electronic Resource
    Mapping of resistance to the potato cyst nematode Globodera rostochiensis from the wild potato species Solanum vernei (1996)
    Springer
    Molecular breeding 2 (1996), S. 51-60 
    Details
    ISSN: 1572-9788
    Keywords: BSA ; Globodera rostochiensis ; potato ; RFLP ; SCAR ; Solanum vernei
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A population of diploid potato (Solanum tuberosum) was used for the genetic analysis and mapping of a locus for resistance to the potato cyst nematode Globodera rostochiensis, introgressed from the wild potato species Solanum vernei. Resistance tests of 108 genotypes of a F1 population revealed the presence of a single locus with a dominant allele for resistance to G. rostochiensis pathotype Ro1. This locus, designated GroV1, was located on chromosome 5 with RFLP markers. Fine-mapping was performed with RAPD and SCAR markers. The GroV1 locus was found in the same region of the potato genome as the S. tuberosum ssp. andigena H1 nematode resistance locus. Both resistance loci could not excluded to be allelic. The identification of markers flanking the GroV1 locus offers a valuable strategy for marker-assisted selection for introgression of this nematode resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171351
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  • 6
    Electronic Resource
    Electronic Resource
    Composition of endogenous alleles can influence the level of antisense inhibition of granule-bound starch synthase gene expression in tetraploid potato plants (1998)
    Springer
    Molecular breeding 4 (1998), S. 343-358 
    Details
    ISSN: 1572-9788
    Keywords: amylose ; antisense RNA ; endogenous allele ; Solanum tuberosum ; T-DNA insertion ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The T-DNA composition was analysed of twelve potato genotypes obtained after transforming a tetraploid cultivar with an antisense granule-bound starch synthase (GBSSI) gene. In five transformants (labelled TB50 nos.) the antisense GBSSI gene was driven by the CaMV 35S promoter, while in the remaining seven (labelled TBK50 nos.) the GBSSI promoter was used. In these twelve transformants the antisense effect on amylose production in potato tuber starch ranged from complete suppression to no discernible inhibition, and the number of T-DNA insertions ranged from one to at least fifteen. The antisense effect of individual T-DNA loci in progeny of these transformants was studied. Progeny containing a single T-DNA showed no inhibition of GBSSI activity. Only multiple, linked T-DNA insertions resulted in substantial antisense inhibition. T-DNA fragments present in duplex in selfed progeny resulted in a larger antisense effect than that in the parent (which contained the T-DNA insertions in simplex). Furthermore, the antisense effects of some T-DNA-containing linkage groups were influenced by the composition of endogenous GBSSI alleles. For practical breeding this implies that (1) the efficiency of obtaining primary potato transformants showing complete inhibition of GBSSI gene expression by antisense RNA is genotype-dependent, and (2) many transformants have to be produced per genotype to be able to select plants with maximum suppression of GBSSI and a minimum number of T-DNA loci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009697725778
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  • 7
    Electronic Resource
    Electronic Resource
    Factors affecting the inhibition by antisense RNA of granule-bound starch synthase gene expression in potato (1995)
    Springer
    Molecular genetics and genomics 246 (1995), S. 745-755 
    Details
    ISSN: 1617-4623
    Keywords: Antisense effect ; Granule-bound starch synthase (GBSS) ; Introns Promoter ; T-DNA copy number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inhibition of expression of specific genes by means of antisense RNA is widely used, although little information is available regarding conditions that affect the efficacy of inhibition. In this study, inhibition of granule-bound starch synthase (GBSS), a key enzyme in starch biosynthesis, is used as a model system. Eleven antisense constructs derived from the full-length GBSS cDNA, the genomic GBSS coding region (gDNA) or fragments of each of these sequences, were analysed with respect to their inhibitory effect. Introduction of full-length gDNA constructs yielded a lower percentage of transgenic clones showing complete inhibition than did introduction of the full-length cDNA constructs. This may be caused by a lower antisense binding capacity of the former due to the relatively low GC content in intron sequences present in the gDNA constructs. The presence of multiple T-DNA insertions was related to a higher degree of inhibition. Putative polyadenylation signals on the antisense strand of the GBSS gene resulted in a premature stop of transcription of some of the antisense genes, as demonstrated by the expression of smaller antisense RNA transcripts. Introduction of antisense constructs driven by the promoter of the (target) GBSS gene resulted in a higher percentage of clones with complete inhibition than introduction of antisense constructs driven by the 35S CaMV promoter. Complete antisense inhibition was achieved in 25% of the clones carrying the antisense construct pKGBA 50, which is based on the GBSS promoter and the full-length GBSS cDNA. Thus, it is concluded that the use of pKGBA50 is very suitable for the modification of the composition of potato tuber starch via antisense RNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290722
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  • 8
    Electronic Resource
    Electronic Resource
    Formation of shoots from leaf axils of Alstroemeria: The effect of the position on the stem (1998)
    Springer
    Plant cell, tissue and organ culture 52 (1998), S. 165-169 
    Details
    ISSN: 1573-5044
    Keywords: age ; in vitro ; Inca lily ; monocots ; micropropagation ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Direct shoot regeneration was induced from leaf explants of Alstroemeria. The explants contained a leaf blade and a small portion of stem node, which were cut from the erect shoots of in vitro multiplicated plantlets. The shoot regeneration capacity of the excised leaf explants was significantly related to the position of the explant on the stem. The youngest explant which was located closest to the shoot apex gave the highest response. A gradient response toward the shoot apex was observed in percentage of shoot regeneration and in the number of shoots per regenerating explant. Histological studies revealed that the shoots were initiated at the leaf axils. The origin of the adventitious buds was located at the epidermal layer of stem peripheral cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006063105940
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  • 9
    Electronic Resource
    Electronic Resource
    Selection of diploid tuberous Solanum hybrids for 2n-egg formation using 2x⋅4x-crosses (1998)
    Springer
    Euphytica 101 (1998), S. 325-339 
    Details
    ISSN: 1573-5060
    Keywords: potato ; sexual polyploidization ; Solanum ; species ; Tuberosum hybrids ; unreduced gametes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diploid families of Tuberosum hybrids as well as Tuberosum-wild species F1 hybrids were generated to select 2n-egg producing genotypes of different genetic backgrounds. Plants were selected if they produced more than four seeds per berry after pollination with tetraploid males (2x⋅ot4x-crosses). From the nine families of Tuberosum hybrids that were derived from one or two 2n-egg producing parents, 12 out of 82 (15%) 2n-egg producing plants were selected. From the 32 families of Tuberosum-wild species F1 hybrids, 21 of 274 (8%) 2n-egg producing plants were selected. The level of 2n-egg formation was estimated in 25 selected diploid hybrids and five control clones (three high, one moderate and one low 2n-egg producers) on the basis of seed set following 2x⋅4x-crosses using 13 tetraploid males in four crossing years. Besides the effect of the diploid 2n-egg producing female on the seed set following 2x⋅4x-crosses (P = 0.0001), there was a significant effect of the tetraploid male (P = 0.0001), whereas the effect of the crossing year (P = 0.0688) was less significant. On the basis of differences in the seed set following 2x⋅4x-crosses as compared to the control clones for low, moderate and high level of 2n-egg formation, the level of 2n-egg formation in two of the newly selected hybrids was classified as very high, four were high, sixteen were moderate and three were low. The significance of the selected hybrids for the genetic analysis of various restitution mechanisms of 2n-egg formation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018391013013
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of cytokinins and lines on plant regeneration from long-term callus and suspension cultures of Allium cepa L. (1999)
    Springer
    Euphytica 108 (1999), S. 83-90 
    Details
    ISSN: 1573-5060
    Keywords: line ; onion ; regeneration ; shallot ; suspension culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Suspension cultures were initiated from callus cultures of Allium cepa, which had been precultured on a solidified medium for 7 months. For another 3 months the 83 callus lines were kept in suspension culture. Each line is derived from a single zygotic embryo, 24 lines from onion and 59 lines from shallot. Of these, 20 suspension lines showed adequate growth and were used to test the effect of cytokinins on plant regeneration. On average, 1.25% of the calli produced shoots on a growth regulator-free medium (MS30: MS basal medium supplemented with 30 g/l sucrose). Thus plant regeneration decreased significantly with time because the overall average plant regeneration frequency was 35.5% after 3 months of culture on solidified medium. Plant regeneration after 3 months proved not to be a reliable predictor of plant regeneration after 10 months in vitro culture. Overall only 0.25–0.88% of the calli produced shoots when the regeneration medium was supplemented with different types and concentrations of cytokinins. Contrary to expectations, the type and concentration of cytokinins could not increase the shoot regeneration capacity. However as expected, the increasing cytokinin concentration (especially TDZ at the range of 1–5 mg/l) led to a decrease in root formation. Plant regeneration proved to be highly dependent upon the line used. The best line was atm24 with an overall shoot regeneration capacity of 4.62% (among the 13 treatments); it had its highest shoot regeneration on MS30 treatment with 12.5%. The results obtained show that for the development of a reliable transformation protocol only young callus material (〈 3 months), which has still a high regeneration potential, can be used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003652211389
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