Search Results - (Author, Cooperation:R. G. Visser)

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  1. 1
    X. Xu ; S. Pan ; S. Cheng ; B. Zhang ; D. Mu ; P. Ni ; G. Zhang ; S. Yang ; R. Li ; J. Wang ; G. Orjeda ; F. Guzman ; M. Torres ; R. Lozano ; O. Ponce ; D. Martinez ; G. De la Cruz ; S. K. Chakrabarti ; V. U. Patil ; K. G. Skryabin ; B. B. Kuznetsov ; N. V. Ravin ; T. V. Kolganova ; A. V. Beletsky ; A. V. Mardanov ; A. Di Genova ; D. M. Bolser ; D. M. Martin ; G. Li ; Y. Yang ; H. Kuang ; Q. Hu ; X. Xiong ; G. J. Bishop ; B. Sagredo ; N. Mejia ; W. Zagorski ; R. Gromadka ; J. Gawor ; P. Szczesny ; S. Huang ; Z. Zhang ; C. Liang ; J. He ; Y. Li ; Y. He ; J. Xu ; Y. Zhang ; B. Xie ; Y. Du ; D. Qu ; M. Bonierbale ; M. Ghislain ; R. Herrera Mdel ; G. Giuliano ; M. Pietrella ; G. Perrotta ; P. Facella ; K. O'Brien ; S. E. Feingold ; L. E. Barreiro ; G. A. Massa ; L. Diambra ; B. R. Whitty ; B. Vaillancourt ; H. Lin ; A. N. Massa ; M. Geoffroy ; S. Lundback ; D. DellaPenna ; C. R. Buell ; S. K. Sharma ; D. F. Marshall ; R. Waugh ; G. J. Bryan ; M. Destefanis ; I. Nagy ; D. Milbourne ; S. J. Thomson ; M. Fiers ; J. M. Jacobs ; K. L. Nielsen ; M. Sonderkaer ; M. Iovene ; G. A. Torres ; J. Jiang ; R. E. Veilleux ; C. W. Bachem ; J. de Boer ; T. Borm ; B. Kloosterman ; H. van Eck ; E. Datema ; B. Hekkert ; A. Goverse ; R. C. van Ham ; R. G. Visser
    Nature Publishing Group (NPG)
    Published 2011
    Staff View
    Publication Date:
    2011-07-12
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Evolution, Molecular ; Gene Duplication ; Gene Expression Regulation, Plant ; Genes, Plant/genetics ; Genetic Variation ; Genome, Plant/*genetics ; *Genomics ; Haplotypes/genetics ; Heterozygote ; Homozygote ; Immunity, Innate ; Inbreeding ; Molecular Sequence Annotation ; Molecular Sequence Data ; Plant Diseases/genetics ; Ploidies ; Solanum tuberosum/*genetics/physiology
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Staff View
    Publication Date:
    2013-03-08
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Acclimatization ; *Agriculture ; *Alleles ; Arabidopsis ; Chromosomes, Plant/genetics ; Circadian Clocks/physiology/radiation effects ; Crops, Agricultural/genetics/growth & development/radiation effects ; Europe ; Flowers/genetics/growth & development ; Gene Expression Regulation, Plant ; Genes, Plant/genetics ; Genetic Variation/*genetics ; Light ; Molecular Sequence Data ; Plant Leaves/metabolism/radiation effects ; Plant Proteins/genetics/metabolism ; Plant Tubers/genetics/growth & development/radiation effects ; Solanum tuberosum/*genetics/*growth & development/radiation effects ; South America ; Time Factors
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  3. 3
    Staff View
    ISSN:
    1365-3040
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Biology
    Notes:
    A highly synchronized in vitro tuberization system, based on single-node cuttings containing an axillary bud, was used to investigate the activity patterns of enzymes involved in the conversion of hexose phosphates and related products during stolon-to-tuber transition of potato (Solanum tuberosum L.). At tuberization the activity of enzymes involved in glycolysis and the oxidative pentose phosphate pathway (OPPP) showed a small but clear increase. This increase reflects a higher capacity of respiratory(-related) metabolism, presumably due to the onset of rapid cell division in the apical part of the tuberizing stolon. During the phase of successive tuber growth these enzymes decreased in activity, suggesting that the concomitant massive starch accumulation is not accompanied by a large increase in respiration. A high degree of positive correlation between the activities of these enzymes could be observed, implying that the level of respiratory metabolism-related enzymes is co-ordinately regulated by the same mechanism of coarse control. The activity pattern of pyrophosphate:fructose-6-phosphate phosphotransferase (PFP) showed no developmental change and does not resemble the activity pattern of the enzymes participating in respiratory(-related) metabolism. Instead, its level of activity is very likely the result of metabolic regulation. The level of the content of the metabolites UDP-glucose (UDPGlc) and glucose-6-phosphate (Glc6P) decreased after the onset of tuberization. This decline indicates that tuber induction is not accompanied by an appreciable increase in the level of the cytosolic hexose phosphate (hexose-P) content but that it rather remains on a low level, which might be a prerequisite in order to maintain a high net rate of sucrose degradation during tuber development. In contrast to UDPGlc and Glc6P, the content of fructose-1,6-bisphosphate (Fru1,6bisP) showed an increase after tuber induction. The overall activities of ADP-glucose pyrophosphorylase (AGPase) and starch phosphorylase (STP) both showed a large increase after tuber initiation, which is consistent with their presumed role in the process of starch synthesis and accumulation during rapid tuber growth.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1046/j.1365-3040.1999.00473.x

    Articles: DFG German National Licenses
  4. 4
    Visser, R. G. ; Oussoren, Wim
    Springer
    Published 1998
    Staff View
    ISSN:
    1432-0517
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Chemistry and Pharmacology
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/

    Articles: DFG German National Licenses
  5. 5
    Visser, R. G.
    Springer
    Published 2000
    Staff View
    ISSN:
    1432-0517
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Chemistry and Pharmacology
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s007690050448

    Articles: DFG German National Licenses
  6. 6
    Jacobsen, E. ; Visser, R. G. F. ; Wijbrandi, J.
    Springer
    Published 1985
    Staff View
    ISSN:
    1432-203X
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract The selection and characterization of 5-methyltryptophan (5-MT) resistant cell lines is described in a dihaploid potato, clone H2578(007). The frequency of resistant calli was increased by treatment of a cell suspension with N-ethyl-N-nitroso-urea. Two lines, 5-MT-21 and 5-MT-26, accumulated tyrosine (160 nMol and 1546 nMol/g fresh callus), and the third, 5-MT-27, accumulated both tyrosine (841 nMol/g fresh callus) and phenylalanine (451 nMol/g fresh callus). In the wildtype tyrosine and phenylalanine content was 65 nMol and 42 nMol/g callus, respectively. The tryptophan content of line 5-MT-26 was significantly increased, from 20 nMol/g to 76 nMol/g fresh callus. The total free amino acid content of the three variant cell lines was higher than that of the wildtype. Variant cell lines 5-MT-21, -26 and -27 showed a low degree of resistance to 5-MT, when grown on a selective medium and were cross-resistant to parafluorophenylalanine and 3-fluorotyrosine, analogues of phenylalanine and tyrosine.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00571304

    Articles: DFG German National Licenses
  7. 7
    Staff View
    ISSN:
    1432-203X
    Keywords:
    Key words Friable embryogenic callus ; Regeneration ; Rhizome ; Alstroemeria
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract  Stem segments of seedlings from two Alstroemeria breeding lines, cultured on media supplemented with 4 mg/l 2,4-dichlorophenoxyacetic acid and 0.5–1.0 mg/l 6-benzylaminopurine (BA), initiated soft callus, which became compact after subculture on a medium with only 0.5 mg/l BA. Friable embryogenic calli were initiated from compact callus on a medium supplemented with 10 mg/l picloram. Proembryos developed from friable embryogenic calli via embryos into plants after subculture on medium supplemented with 0.1 mg/l BA. The proembryos formed friable embryogenic calli again after culture on medium supplemented with 10 mg/l picloram. The total time needed to regenerate a complete plantlet from friable callus was approximately 6 months. This system for the production of embryogenic material is considered to have valuable applications for genetic transformation in Alstroemeria.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s002990050768

    Articles: DFG German National Licenses
  8. 8
    Staff View
    ISSN:
    1432-203X
    Keywords:
    direct somatic embryogenesis ; primary and higher cycles ; liquid culture ; shoot development
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Summary In cassava a cyclic system of somatic embryogenesis was developed. Primary (torpedo shaped or germinated) embryos, originating from leaf lobes, could only be obtained after culture on solid medium. Cyclic embryos, originating from embryos, could be obtained in both liquid and on solid medium. The production of embryos in liquid medium was distinctly higher, faster and more synchronized than on solid medium. Lower densities and fragmentation of starting embryos improved the production significantly. The highest production found was 32.1 embryos per initial embryo. In all treatments the explants initiated multiple embryos. The production of single embryos was achieved by pressing starting embryos through a fine meshed sieve, indicating that embryos can be produced from a piece of tissue with a restricted number of cells. The shoot conversion rate of embryos from liquid medium was comparable with that of embryos from solid medium.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00237059

    Articles: DFG German National Licenses
  9. 9
    Staff View
    ISSN:
    1573-5028
    Keywords:
    Branching enzyme ; cassava ; cDNA ; expression pattern ; Manihot esculenta Crantz ; sequence homology
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Branching enzyme is involved in the synthesis of amylopectin in plant reserve starch. A cDNA coding for cassava (Manihot esculenta Crantz) branching enzyme was cloned from a λgt11 cDNA library using a potato cDNA probe. The cloned cDNA was partially sequenced. The sequence data confirmed the identity of the clone when compared to that of potato, the homology being ca. 80% at the nucleotide level and 85% at the amino acid level. Furthermore, the cloned cassava cDNA was able to restore branching enzyme activity in a branching enzyme deficient Escherichia coli mutant. Results of the Southern analysis suggested that there is a single gene for this particular branching enzyme in the cassava genome. Study of expression patterns by northern hybridization showed that the gene is highly expressed in tubers. The transcript is detectable in stem and petiole, but not in leaves. In roots, the mRNA is hardly present. The expression levels at different stages of tuber growth are similar with exception of very young tubers in which it is relatively low. It is also shown that there is a difference in the level of branching enzyme expression between different cassava genotypes.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00027152

    Articles: DFG German National Licenses
  10. 10
    Staff View
    ISSN:
    1573-5028
    Keywords:
    antisense effect ; granule-bound starch synthase ; cassava ; cDNA ; heterologous gene ; potato
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract A tuber-specific cDNA library of cassava (Manihot esculenta Crantz) was constructed and a full-length cDNA for granule-bound starch synthase (GBSS, also known as waxy protein), the enzyme responsible for the synthesis of amylose in reserve starch, was cloned. Sequencing of the cloned cDNA showed that it has 74% identity with potato GBSS and 60–72% identity with GBSS from other plant species. The cDNA encodes a 608 amino acid protein of which 78 amino acids form a chloroplast/amyloplast transit peptide of 8.37 kDa. The mature protein has a predicted molecular mass of 58.61 kDa (530 amino acids). Comparison of the GBSS proteins of various plant species and glycogen synthase of bacteria showed extensive identity among the mature form of plant GBSS proteins, in which the monocots and dicots form two separate branches in the evolutionary tree. From analysis of the genomic DNA of allotetraploid cassava, it is shown that GBSS is a low-copy-number gene. GBSS transcript is synthesized in a number of different organs, but most abundantly in tubers. Potato plants were transformed with the cassava GBSS cDNA in antisense orientation fused between the potato GBSS promoter and the nopaline synthase terminator. The expression of the endogenous GBSS gene in these transgenic potato plants was partially or completely inhibited. Complete inhibition of GBSS activity by the cassava antisense gene resulted in absence of GBSS protein and amylose giving rise to almost complete amylose-free potato starch. This shows that also heterologous genes can be used to achieve antisense effects in other plant species.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00021811

    Articles: DFG German National Licenses
  11. 11
    Staff View
    ISSN:
    1573-5028
    Keywords:
    Agrobacterium tumefaciens ; adventitious shoot regeneration ; transformation ; homozygous potato
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Transformed potato (Solanum tuberosum) plants were obtained from homozygous diploid potato by using a transformation procedure in combination with an adventitious shoot regeneration method. Leaf and stem explants were inoculated with an Agrobacterium tumefaciens strain which contained a binary vector (pVU 1011) carrying the neomycin phosphotransferase gene. Shoot regeneration most effectively on stem explants, occurred within six weeks directly from the explants without introducing a callus phase. A strong seasonal influence on transformation efficiencies was observed. Analysis of a number of randomly selected regenerated shoots for their ability to root and form shoots on kanamycin-containing medium shows that over 90% of the regenerated shoots obtained are transformed. In a number of shoots transformation was confirmed by a test for the presence and expression of the NPT-II gene.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00043210

    Articles: DFG German National Licenses
  12. 12
    Staff View
    ISSN:
    1432-2048
    Keywords:
    Antisense inhibition ; Branching enzyme (potato) ; Co-suppression (gene activity) ; Gene activity (branching enzyme) ; Solanum (branching enzyme) ; Starch physico chemical properties
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract One isoform of the branching enzyme (BE; EC 2.4.1.18) of potato (Solarium tuberosum L.) is known and catalyses the formation of α-1,6 bonds in a glucan chain, resulting in the branched starch component amylopectin. Constructs containing the antisense or sense-orientated distal 1.5-kb part of a cDNA for potato BE were used to transform the amylose-free (amf) mutant of potato, the starch of which stains red with iodine. The expression of the endogenous BE gene was inhibited either largely or fully as judged by the decrease or absence of the BE mRNA and protein. This resulted in a low percentage of starch granules with a small blue core and large red outer layer. There was no effect on the amylose content, degree of branching or λmax of the iodine-stained starch. However, when the physico-chemical properties of the different starch suspensions were assessed, differences were observed, which although small indicated that starch in the transformants was different from that of theamf mutant.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00620049

    Articles: DFG German National Licenses
  13. 13
    Staff View
    ISSN:
    1432-203X
    Keywords:
    Key words Cassava ; Protoplast culture ; Friable embryogenic callus
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Protoplasts were isolated from friable embryogenic callus (FEC) and from suspensions derived from FEC of cassava genotype TMS60444. Suspensions yielded the highest number of protoplasts (1.5×106 protoplasts/g fresh weight). Protoplasts plated at a density of 105–106/ml in a medium supplemented with 0.5 mg/l α-naphthaleneacetic acid and 1 mg/l zeatin began dividing after 3 days, and after 30 days this resulted in an absolute plating efficiency as high as 2.5%. After 2 months of culture, 60% of the developed calli were highly friable and in appearance identical to the original FEC. The protoplast derived FEC was first purified through two rounds of selection of 3 weeks each before beeing cultured for regeneration of plants. This was done by culturing the protoplast-derived FEC for 11 weeks on maturation medium, yielding a maximum of 184 organized embryos per 10.000 initially cultured protoplasts. Most of the organized embryos were torpedo shaped and matured after they had been isolated from the calli and transferred to fresh medium. Mature embryos were multiplied by secondary somatic embryogenesis at high efficiency (〉90%) on a medium supplemented with 8 mg/l 2,4-dichlorophenoxyacetic acid. About 30% of the mature secondary somatic embryos developed into shoots after transfer to a medium supplemented with 1 mg/l N6-benzylaminopurine (BAP). Shoots rooted readily on a medium without BAP.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s002990050550

    Articles: DFG German National Licenses
  14. 14
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Agrobacterium rhizogenes ; Solanum tuberosum ; Binary vector ; Neomycin phosphotransferase ; β-Glucuronidase
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Summary Transgenic shoots were regenerated from eight diploid potato hairy root clones obtained by transformation with Agrobacterium rhizogenes harboring next to its wild-type Ri-plasmid a binary vector containing the neomycin phosphotransferase and the β-glucuronidase genes. The plants exhibited the typical hairy root phenotype. Of the plants isolated, 58% were tetraploid and 38% were diploid. Flowering and tuberization was much better in the diploid than in the tetraploid plants. Transgenic plants formed a significantly larger root system when grown on kanamycin-containing medium as compared to growth on kanamycin-free medium. Direct evidence for genetic transformation was obtained by opine, neomycin phosphotransferase and β-glucuronidase assays, and by molecular hybridization. Fourteen flowering diploid plants were reciprocally crossed with untransformed S. tuberosum plants, but only six were successful. Seedlings obtained from four crosses showed that all traits were transmitted to the offspring. Molecular analysis confirmed the presence of multiple integrations (copies) of both vector T-DNA and Ri-T-DNA. The genetic data, furthermore, suggest that the traits derived from Ri-T-DNA and binary vector T-DNA are linked, as no recombination between the different traits was observed.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00262567

    Articles: DFG German National Licenses
  15. 15
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Key words Gene dosage  ;  Granule bound starch synthase  ;  amf mutant  ;  Physico-chemical properties  ;  Solanum tuberosum
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract  A gene-dosage population was obtained by crossing two genotypes that were duplex for the GBSS allele. Nulliplex, simplex, duplex or triplex*quadruplex plants could be identified by monitoring the segregation of red and blue microspores after staining with iodine. GBSS activity was significantly different for all groups and showed an almost linear dosage effect for the wildtype GBSS gene. A dosage effect was found for amylose content that was not linear. The amylose content was similar for both the duplex and triplex*quadruplex group. Within the simplex group, differences in amylose content were found, which might be due to a different genetic background. There was no linear correlation between GBSS activity and amylose content. A certain level of GBSS activity led to a maximum amount of amylose, and further increase in GBSS activity did not result in a further increase in amylose content. The presence of one or more wildtype GBSS allele(s), and therefore the presence of amylose in the starch granules, had a great influence on the physico-chemical properties of the starch suspensions.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s001220050102

    Articles: DFG German National Licenses
  16. 16
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Solanum tuberosum ; Mutant ; Starch composition ; Granule-bound starch synthase ; amylose-free
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Summary An amylose-free potato mutant was isolated after screening 12,000 minitubers. These minitubers had been induced on stem segments of adventitious shoots, which had been regenerated on leaf explants of a monoploid potato clone after Röntgen-irradiation. The mutant character is also expressed in subterranean tubers and in microspores. Starch granules from the mutant showed a strongly reduced activity of the granule bound starch synthase and loss of the major 60 kd protein from the starch granules.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00249167

    Articles: DFG German National Licenses
  17. 17
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Key words Alstroemeria aurea ; Repetitive DNA ; FISH-fluorescence in situ hybridization ; Heterochromatin ; Phylogeny
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract  Three repetitive DNA sequences were isolated from a genomic DNA library of the ornamental Alstroemeria aurea Graham. Two repeats, A001-I and A001-II, were quite homologous and highly A. aurea-specific. A001-I was a 217-bp sequence with several telomeric TTTAGGG repeats at the 5′ end and a unique sequence of 98 bp at the other end. The third repeat, A001-IV, was a 840-bp sequence which contained two sub-sequences of 56 and 74 bp respectively, previously found in chloroplast (cp) DNA of tobacco and spinach and to a lesser extent in the cpDNA of maize and rice. Repeat A001-IV was not species-specific and its hybridization signal was weaker than the other repeats. Fluorescence in situ hybridization (FISH) revealed the A. aurea-specific repeats to be located in the heterochromatic regions of all A. aurea chromosomes. The differences in FISH pattern make them useful tools for karyotype analysis. The non-species-specific sequence A001-IV gave a dispersed signal over all the Alstroemeria chromosomes in an interspecific hybrid. The potential use of these repetitive DNA sequences for the study of phylogenetic relationships within the genus Alstroemeria is discussed.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s001220050505

    Articles: DFG German National Licenses
  18. 18
    Staff View
    ISSN:
    1432-2242
    Keywords:
    In situ hybridization ; Mitotic chromosomes ; Potato ; Repetitive sequences
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Summary An in situ hybridization procedure was developed for mitotic potato chromosomes by using a potato 24S rDNA probe. This repetitive sequence hybridized to the nucleolar organizer region (NOR) of chromosome 2 in 95%–100% of the metaphase plates. Another repetitive sequence (P5), isolated from the interdihaploid potato HH578, gave a “ladderpattern” in genomic Southern's of Solanum tuberosum and Solanum phureja, but not in those of Solanum brevidens and two Nicotiana species. This sequence hybridized predominantly on telomeric and centromeric regions of all chromosomes, although chromosomes 7, 8, 10 and 11 were not always labeled clearly.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00265343

    Articles: DFG German National Licenses
  19. 19
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Complementation ; Granule-bound starch synthase ; Amylose content ; Gene expression ; Inheritance
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract Granule-bound starch synthase (GBSS) catalyses the synthesis of amylose in starch granules. Transformation of a diploid amylose-free (amf) potato mutant with the gene encoding GBSS leads to the restoration of amylose synthesis. Transformants were obtained which had wild-type levels of both GBSS activity and amylose content. It proved to be difficult to increase the amylose content above that of the wild-type potato by the introduction of additional copies of the wild-type GBSS gene. Staining of starch with iodine was suitable for investigating the degree of expression of the inserted GBSS gene in transgenic amf plants. Of the 19 investigated transformants, four had only red-staining starch in tubers indicating that no complementation of the amf mutation had occured. Fifteen complemented transformants had only blue-staining starch in tubers or tubers of different staining categories (blue, mixed and red), caused either by full or partial expression of the inserted gene. Complementation was also found in the microspores. The segregation of blue- and red-staining microspores was used to analyse the inheritance of the introduced GBSS genes. A comparison of the results from microspore staining and Southern hybridisation indicated that, in three tetraploid transgenics, the gene was probably inserted before (duplex), and in all others after, chromosome doubling (simplex). The partial complementation was not due to methylation of the HPAII/MSPI site in the promoter region. Partially complemented plants had low levels of mRNA as was found when the GBSS expression levels were inhibited by anti-sense technology.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00223647

    Articles: DFG German National Licenses
  20. 20
    Staff View
    ISSN:
    1432-2242
    Keywords:
    Gene dosage ; Granule bound starch synthase ; amf mutant ; Physico-chemical properties ; Solanum tuberosum
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Notes:
    Abstract A gene-dosage population was obtained by crossing two genotypes that were duplex for the GBSS allele. Nulliplex, simplex, duplex or triplex/quadruplex plants could be identified by monitoring the segregation of red and blue microspores after staining with iodine. GBSS activity was significantly different for all groups and showed an almost linear dosage effect for the wildtype GBSS gene. A dosage effect was found for amylose content that was not linear. The amylose content was similar for both the duplex and triplex/quadruplex group. Within the simplex group, differences in amylose content were found, which might be due to a different genetic background. There was no linear correlation between GBSS activity and amylose content. A certain level of GBSS activity led to a maximum amount of amylose, and further increase in GBSS activity did not result in a further increase in amylose content. The presence of one or more wildtype GBSS allele(s), and therefore the presence of amylose in the starch granules, had a great influence on the physico-chemical properties of the starch suspensions.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00222961

    Articles: DFG German National Licenses