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  • starch composition  (4)
  • Amylose content  (1)
  • Chlorateresistance  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 64 (1982), S. 83-90 
    ISSN: 1432-2242
    Schlagwort(e): Arabidopsis thaliana ; Mutant ; Chlorateresistance ; Nitrate reductase ; Cytochrome-c reductase ; Xanthine dehydrogenase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chlorate resistant mutants of Arabidopsis thaliana were isolated, of which 10 exhibited a lowered nitrate reductase activity and 51 were chlorate-resistant because of an impaired uptake of chlorate. The 51 mutants of this type are all affected in the same gene. The mutants with a lowered nitrate reductase activity fall into 7 different complementation groups. Three of these mutants grow poorly on media with nitrate as the sole nitrogen source, while the others apparently can reduce sufficient nitrate to bring about growth. In all cases a low nitrate reductase activity coincides with an enhanced nitrite reductase activity. After sucrose gradient centrifugation of wildtype extracts nitrate reductase is found at the 8S position, whereas cytochrome-c reductase is found both at 4 and 8S positions. It is suggested that the functional nitrate reductase is a complex consisting of 4S subunits showing cytochrome-c reductase activity and a Mo-bearing cofactor. All mutants except B25 are capable of assembling the 4S subunits into complexes which for most mutants have a lower S value and exhibit a lower nitrate reductase activity than the wildtype complexes. Since the mutants B25 and B73 exhibit a low xanthine dehydrogenase activity, the Mo-bearing cofactor is probably less available in these mutants than in the wildtype. B73 appears to be the only mutant which is partly repaired by excessive Mo. The possible role of several genes is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1871-4528
    Schlagwort(e): minitubers ; starch composition ; mutant detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Small amounts of potato tuber and leaf tissues are extracted in perchloric acid. After staining with I2-KI solution absorbancies at 618 and 550 nm are measured. The amylose/amylopectin ratio can be estimated from the ratio of the absorbancies by using a formula or a graph in which the specific absorptions of the two compounds are introduced. Weighing of samples is not required. The method can be used for the estimation of the starch composition of minitubers and is especially suitable for the detection of mutants with an altered starch composition.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1617-4623
    Schlagwort(e): Amylose content ; Antisense RNA ; Dominant (hemizygous) suppression ; Granule-bound starch synthase ; Transgenic potato
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Granule-bound starch synthase [GBSS; EC 24.1.21] determines the presence of amylose in reserve starches. Potato plants were transformed to produce antisense RNA from a gene construct containing a full-length granule-bound starch synthase cDNA in reverse orientation, fused between the cauliflower mosaic virus 35S promoter and the nopaline synthase terminator. The construct was integrated into the potato genome by Agrobacterium rhizogenes-mediated transformation. Inhibition of GBSS activity in potato tuber starch was found to vary from 70% to 100%. In those cases where total suppression of GBSS activity was found both GBSS protein and amylose were absent, giving rise to tubers containing amylose-free starch. The variable response of the transformed plants indicates that position effects on the integrated sequences might be important. The results clearly demonstrate that in tubers of potato plants which constitutively synthesize antisense RNA the starch composition is altered.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium rhizogenes ; antisense RNA ; granule-bound starch synthase ; Solanum tuberosum ; starch composition ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Granule-bound starch synthase (GBSS) catalyses the synthesis of amylose in starch granules. Analysis of antisense RNA mediated inhibition of GBSS gene expression in large numbers of tubers from in vitro grown, greenhouse grown and field grown transgenic potato plants revealed stable and total inhibition of GBSS gene expression in one clone. In three other transgenic genotypes partial and unstable inhibition was found. In these genotypes both GBSS activity and amylose content were remarkably reduced compared with the non-transformed control genotype. No relationship was found between the level of inhibition of GBSS gene expression and yield and dry matter content.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1573-5060
    Schlagwort(e): Solanum tuberosum ; potato ; mutant ; starch composition ; amylose-free ; embryo rescue ; inheritance ; phenotype ; breeding ; karyotype
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The amylose-free (amf) potato mutant 86.040 has been characterized phenotypically and genotypically. Not only storage starch in tubers and metabolic starch in leaves but also starch in cells with specific functions, such as columella cells in the root cap and guard cells of stomata, was amylose-free. Doubled amf-clones of 86.040 flowered well, but the percentage of stainable pollen was low (8.2%). Therefore, they were used as female parent in crosses with diploid amylose-containing plants. Over 400 pollinations gave 13 berries, all dropping off prematurely; they contained 78 ovules with embryos at different developmental stages. Twenty F1 plants were obtained by embryo rescue, all having amylose starch. Three of them were characterized more extensively. They flowered well and pollen stainabilitity as well as seed set were high. Analysis of the F1 plants and of F1 × F1 progeny plants showed that the amf-character is monogenic and recessive. The locus involved was designated amf +and the mutated allele amf.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1573-5060
    Schlagwort(e): Solanum tuberosum ; potato ; adventitious shoot induction ; minituber induction ; starch composition ; cytology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A three step procedure for adventitious shoot regeneration on leaf explants of monoploid potato clone H7322 and a minituber induction procedure on stem segments have been described. Chromosome counts on 92 adventitious shoots showed that 85% of them had been polyploidized, i.e., 71% were diploid, 1% tetraploid, and 13% were mixoploid. Cytophotometric studies on nuclei of soil grown tubers of tetraploid cv Astarte, of 1x, 2x and 4x adventitious shoots of H7322, and of diploid H2578 showed in all cases polyploidization with prominent classes up to 8C and 16C. However, nuclei of pith cells of 5 weeks old minitubers which had developed on monoploid H7322 itself or on 1x adventitious shoots of H7322 showed predominantly 1C and 2C values. Pith cells of minitubers of monoploid H7322 were screened, after iodine staining, for the presence of variant cells containing reddish-brown staining (amylose-free) starch. In more than 75% of the investigated minitubers one or a few of such variant cells were found indicating that such a variation occurs in minitubers of monoploid potato and that this variant character is expressed in cells of vegetative storage organs like potato tubers.
    Materialart: Digitale Medien
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