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  • 1
    ISSN: 1432-2145
    Keywords: Polymerase chain reaction ; Self-incompatibility ; Solanaceae ; Ribonuclease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polymerase chain reaction (PCR) has been used to clone two S-alleles (S13 and S14) from Solanum chacoense. The two alleles do not cross-hybridize on genomic Southern blots or on northern blots using stylar RNA. Although the S14 message was not detected in a stylar cDNA library prepared from mature flowers, a full-length copy of the S13 coding sequence was isolated by screening with the PCR fragment. We have analysed the sequences of the S13 cDNA and the S14 PCR fragment (60% of the mature protein coding sequence) in the context of S-RNase evolution, and propose that random point mutations may be sufficient to generate new S-alleles. Based on a phylogenetic tree composed of RNase sequences containing the conserved RNase motifs HGLWP and KHGXC, we suggest that gametophytic self-incompatibility genes are RNase genes that have acquired a new function in the gametophytic self-incompatibility system early in the evolution of flowering plants.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 407 (2000), S. 649-651 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Many flowering plants avoid inbreeding through a genetic mechanism termed self-incompatibility. An extremely polymorphic S-locus controls the gametophytic self-incompatibility system that causes pollen rejection (that is, active arrest of pollen tube growth inside the style) when an ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-203X
    Keywords: Dioscorea abyssinica ; Dioscorea alata ; In vitro tuberization ; Yam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nodal cuttings of Dioscorea alata L. ‘Brazo fuerte’ and D. abyssinica Hoch. were cultured in vitro to assess the influence of NAA on the production of microtubers. In D. alata, high concentrations of NAA (27 and 54 μM) favored the production of large microtubers, whereas the highest number of microtubers was obtained with 2.7 μM. D. abyssinica was found to be more sensitive to NAA since concentrations higher than 0.27 μM promoted the growth of callus on the root system. In this species, the production of the largest microtubers was obtained at 2.7 μM whereas the number of microtubers was not affected by any concentration tested. In D. alata, the effects of ABA and BAP were also evaluated. The weight of the microtubers increased with increasing concentrations of ABA. This effect, however, was observed only on expiants cultured under 8 h photoperiod, but not on those cultured under 16 h. Finally the presence of BAP at concentrations as low as 0.22 μM adversely affected the survival of the explants.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 199-209 
    ISSN: 1573-5044
    Keywords: anther culture ; diploid potato ; effective factors ; heritability ; leaf disc culture ; regenerative capacity ; Solanum chacoense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two diploid clones of self-incompatible Solanum chacoense Bitt. with androgenetic ability were tested for anther and leaf disc culture response together with eight of their reciprocal F1 hybrids. Large differences were found among genotypes in frequency of anther induction as well as in the phase of plant regeneration. Anthers harvested in June showed a significantly higher percentage of response (17.5%) at the induction phase than those collected in July (13.8%) or August (12.7%). The lowest induction frequency was observed in May (7.3%). By contrast, plant regeneration from induced anthers did not vary during this time. Genotypic differences were also observed in leaf disc response. The two parental clones and two of their hybrids failed to produced any shoots. Among the remaining genotypes, two had only sporadic occurrence of shoot formation, two gave an intermediate response (15% and 24% of their discs carried shoots), whereas the discs of the two remaining genotypes responded well to culture (68% and 77%). The genetic analysis performed on the reciprocal hybrids revealed that a positive significant correlation existed between anther induction and leaf disc response (Spearman's r=0.82; p=0.01). This suggests that, under our conditions, these two aspects of tissue culture might share a common system of genetic control. Estimates of broad sense heritabilities, for leaf disc culture, 83% were obtained and the number of effective factors involved in the control of tissue culture response, indicated a relatively simple genetic control. Finally, considering the potentialities opened by the use of RFLP analysis, it might be possible to find probes that are linked with genes involved in tissue culture competence.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 2 (1983), S. 199-206 
    ISSN: 1573-5044
    Keywords: in vitro ; flowering ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Meristem-derived plantlets of cassava (Manihot esculenta Crantz) were induced to flower in vitro. Five genotypes out of 13 consistently responded to our culture conditions giving rise to male or female flowers. Male flowers contained anthers in which meiosis occurred and apparently normal pollen grains were formed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 26 (1991), S. 147-152 
    ISSN: 1573-5044
    Keywords: ammonium nitrate ; Dioscorea abyssinica ; Dioscorea alata ; in vitro tuberization ; photoperiod ; yam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nodal cuttings of D. alata L. ‘Barzo fuerte’ and ‘Florido’, as well as of D. abyssinica Hoch, were cultured in vitro in order to assess the influence of the photoperiod on the production of microtubers. For both species, the highest number of microtubers was obtained under 16 and 24-h photoperiods, whereas larger microtubers were generally produced at 8-h photoperiod. In D. alata, further increase in microtuber size was observed in a culture medium where NH4NO3 was omitted. This effect was less noticeable in D. abyssinica.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5028
    Keywords: glucuronidase ; post-transcriptional regulation ; transgenic plants ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of the levels of starch phosphorylase mRNA and its product in the various organs of the potato plant indicates that the gene is differentially regulated, leading to a high accumulation of the gene product in tubers. The amount of phosphorylase transcripts synthesized in nuclei isolated from tubers and leaves indicates that the difference in the steady-state levels of phosphorylase mRNA in these organs can be explained by different rates of initiation of transcription. However, while rates of initiation of transcription are similar in tubers and stems, the steady-state level of phosphorylase mRNA is much lower in the stem. Transgenic potato plants expressing the β-glucuronidase (GUS) gene under the control of 5′-flanking sequences of the phosphorylase gene exhibited high levels of GUS activity in petioles, stems, stolons, tubers and roots, but low levels in leaves. This confirms the results of transcription assays observed for leaves, stems and tubers, and indicates that accumulation of phosphorylase mRNA in stems and tubers is not controlled solely by transcription initiation. Finally, histochemical analysis for GUS activity in transgenic potato plants suggests that transcription of the phosphorylase gene predominantly occurs in starch-containing cells associated to vascular tissues, and suggests a role for starch phosphorylase in the mobilization of starch stored along the translocation pathway.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 27 (1991), S. 15-21 
    ISSN: 1573-5044
    Keywords: in vitro ; Iris pseudacorus ; I. setosa ; I. versicolor ; root culture ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for plant regeneration of Iris via somatic embryogenesis is described. Root and leaf pieces from in vitro-grown plants of several genotypes of rhizomatous Iris sp. were cultured in vitro. Callus induction occurred only on root cultures incubated under low light intensity (35 μmol m-2 s-1) on two induction media containing 2,4-D (4.5 or 22.5 μM), NAA (5.4 μM) and kinetin (0.5 μM). Somatic embryos developed after transfer of callus onto four regeneration media containing 9 or 22 μM BA, or 5 μM kinetin and 2 μM TIBA or 9 μM BA and 4 μM TIBA. Plantlets could be obtained from these somatic embryos. Genotypic differences were found both in callus induction and somatic embryo formation, with I. pseudacorus responding better than I. versicolor or I. setosa. Cytological analysis performed on root tips of 80 regenerated plants revealed that two of the I. pseudacorus regenerants were tetraploid.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 23 (1993), S. 1079-1085 
    ISSN: 1573-5028
    Keywords: Brassica ; Solanum ; stigma ; style ; self-incompatibility ; multigenic family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, the tissue printing technique has been used to rapidly localize in female tissues the presence of specific mRNA representing the products (or some of the products) of the self-incompatibility S-locus gene(s). The methodology, initially developed for Brassica oleracea (sporophytic self-incompatibility) has been successfully employed on Solanum chacoense (gametophytic self-incompatibility). In the Brassica system tissue printing has allowed rapid discrimination between S alleles belonging to class 1 (dominant types) vs. class 2 (recessive types), and thus parallels findings obtained by restriction analyses. In the Solanum system the level of the S-RNase messages was analysed by scanning laser densitometry, and it was found that the message levels of the allele S14 declined faster than those coming from S13 in mature flowers.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-5028
    Keywords: amino acid replacement ; new S alleles generation ; S allele specificity ; S phenotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic clone of the S11 allele from the self-incompatibility locus (S locus) in Solanum chacoense Bitt. has been isolated by cross-hybridization to the S. chacoense S13 allele and sequenced. The sequence of the S11 allele contains all the features expected for S genes of the Solanaceae, and S11 expression, as assessed by northern blots and RNA-PCR, was similar to that of other S. chacoense S alleles. The S11 protein sequence shares 95% identity with the phenotypically distinct S13 protein of S. chacoense and is the gametophytic S allele with the highest similarity to an existing allele so far discovered. Only 10 amino acid changes differentiate the mature proteins from these two alleles, which sets a new lower limit to the number of changes that can produce an altered S allele specificity. The amino acid substitutions are not clustered, suggesting that an accumulation of random point mutations can generate S allele diversity. The S11 intron is unusual in that it could be translated in frame with the coding sequence, thus suggesting an additional mechanism for the generation of new S alleles.
    Type of Medium: Electronic Resource
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