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  • 1
    ISSN: 1432-203X
    Keywords: forage grasses ; Festuca pratensis ; suspension cultures ; protoplasts ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Suspension cultures from mature embryo-derived compact callus were initiated in seven meadow fescue (Festuca pratensis Huds.) cultivars. Four to six months after initiation, embryogenic suspension cultures with a moderate growth rate were established from three of them (cvs. Barmondo, Belimo and Leopard). These suspension cultures showed the capacity, maintained over six months, to regenerate green plants which could be grown to maturity under greenhouse conditions. Morphogenic suspension cultures from single genotypes of three F. pratensis cultivars (cvs. Barmondo, Belimo and Leopard) yielded large numbers of protoplasts, which upon culture in agarose beads using nurse cells formed microcalli with an overall plating efficiency in the range of 10-3 to 10-4. Mature plants were reproducibly regenerated and established in soil, from such protoplasts during a period of six months. The regeneration of fertile plants from protoplasts derived from suspension cultures of meadow fescue and its implications on gene transfer technology for this species are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-203X
    Keywords: Festuca pratensis ; suspension cultures ; protoplasts ; plant regeneration ; somaclonal variation ; genetic fidelity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cytological and molecular analysis was performed to assess the genetic uniformity and true-to-type character of plants regenerated from 20 week-old embryogenic suspension cultures of meadow fescue (Festuca pratensis Huds.), and compared to protoplastderived plants obtained from the same cell suspension. Cytological variation was not observed in a representative sample of plants regenerated directly from the embryogenic suspensions and from protoplasts isolated therefrom. Similarly, no restriction fragment length polymorphisms (RFLPs) were detected in the mitochondrial, plastid and nuclear genomes in the plants analyzed. Randomly amplified polymorphic DNA markers (RAPDs) have been used to characterise molecularly a set of mature meadow fescue plants regenerated from these in vitro cultures. RAPD markers using 18 different short oligonucleotide primers of arbitrary nucleotide sequence in combination with polymerase chain reaction (PCR) allowed the detection of pre-existing polymorphisms in the donor genotypes, but failed to reveal newly generated variation in the protoplast-derived plants compared to their equivalent suspensionculture regenerated materials. The genetic stability of meadow fescue plants regenerated from suspension cultures and protoplasts isolated therefrom and its implications on gene transfer technology for this species are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 85 (1993), S. 536-540 
    ISSN: 1432-2242
    Keywords: Molecular markers ; Restriction fragment length polymorphism ; Oryza sativa L ; Isozymes ; Rainfed lowland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Photoperiod-sensitive rice (Oryza sativa L.) cultivars are widely grown in rainfed lowland areas with unfavorable water regimes. A molecular marker for the trait would be useful in genetic and physiological studies and in developing improved photoperiod-sensitive cultivars. Previous genetic studies identified a major gene for photoperiod sensitivity on chromosome 6. We have tested an isozyme marker and several RFLP probes mapping to chromosome 6 in an attempt to identify marker(s) tightly linked to photoperiod sensitivity in tropical rice cultivars. We report here that the isozyme gene Pgi-2 is linked (23.2±4.7 cM) to the photoperiod-sensitivity gene in the cultivar GEB-24. Although association of duration with Pgi-2 alleles can be used to detect segregation of the photoperiod sensitivity gene in crosses, it will probably not be useful as a marker in selection because of its loose linkage. In contrast, a gene for photoperiod sensitivity in the cultivar Puang Rai 2 was found to be closely linked to the rice genomic clone RG64. Among 15 F3 lines homozygous for photoperiod insensitivity, no recombinants were detected with RG64. This clone is thus an excellent probe to follow segregation of the major photoperiod-sensitivity gene in rice crosses.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 76 (1988), S. 815-829 
    ISSN: 1432-2242
    Keywords: Oryza sativa ; Molecular markers ; RFLP ; Genetic map ; Trisomies ; DNA methylalion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the construction of an RFLP genetic map of rice (Oryza sativa) chromosomes. The map is comprised of 135 loci corresponding to clones selected from a PstI genomic library. This molecular map covers 1,389 cM of the rice genome and exceeds the current classical maps by more than 20%. The map was generated from F2 segregation data (50 individuals) from a cross between an indica and javanica rice cultivar. Primary trisomics were used to assign linkage groups to each of the 12 rice chromosomes. Seventy-eight percent of the clones assayed revealed RFLPs between the two parental cultivars, indicating that rice contains a significant amount of RFLP variation. Strong correlations between size of hybridizing restriction fragments and level of polymorphism indicate that a significant proportion of the RFLPs in rice are generated by insertions/delections. This conclusion is supported by the occurrence of null alleles for some clones (presumably created by insertion or deletion events). One clone, RG229, hybridized to sequences in both the indica and javanica genomes, which have apparently transposed since the divergence of the two cultivars from their last common ancestor, providing evidence for sequence movement in rice. As a by product of this mapping project, we have discovered that rice DNA is less C-methylated than tomato or maize DNA. Our results also suggest the notion that a large fraction of the rice genome (approximately 50%) is single copy.
    Type of Medium: Electronic Resource
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