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  • 1
    ISSN: 1432-2242
    Keywords: Homoeologous chromosome pairing ; Ph1 pairing regulator ; Genome relationships ; Euhaploid ; Giemsa N-banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chromosome pairing and chiasma frequency were studied in bread wheat euhaploids (2n = 3x = 21; ABD genomes) with and without the major pairing regulatorPh1. This constitutes the first report of chromosome pairing relationships among the A, B, and D genomes of wheat without the influence of an alien genome. AllPh1 euhaploids had very little pairing, with 0.62–1.05 rod bivalents per cell; ring bivalents were virtually absent and mean arm-binding frequency (c) values ranged from 0.050 to 0.086. In contrast, theph1b euhaploids had extensive homoeologous pairing, with chiasma frequency 7.5–11.6 times higher than that in thePh1 euhaploids. They had 0.53–1.16 trivalents, 1.53–1.74 ring bivalents, and 2.90–3.57 rod bivalents, withc from 0.580 to 0.629. N-banding of meiotic chromosomes showed strongly preferential pairing between chromosomes of the A and D genomes; 80% of the pairing was between these genomes, especially in the presence of theph1b allele. The application of mathematical models to unmarked chromosomes also supported a 2∶1 genomic structure of theph1b euhaploids. Numerical modeling suggested that about 80% of the metaphase I association was between the two most related genomes in the presence ofph1b, but that pairing under Ph1 was considerably more random. The data demonstrate that the A and D genomes are much more closely related to each other than either is to B. These results may have phylogenetic significance and hence breeding implications.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 95 (1997), S. 757-763 
    ISSN: 1432-2242
    Keywords: Key words Alien gene transfer ; Intergeneric hybrids ; Molecular markers ; Thinopyrum ; Triticum turgidum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The objective of this study was to detect the presence of alien chromatin in intergeneric hybrids of durum wheat (Triticum turgidum, 2n=4x=28; AABB genomes) with the perennial grass Thinopyrum junceiforme (2n=4x=28; J1J1J2J2) using RAPD markers. The first step was to identify amplification of species-specific DNA markers in the parental grass species and durum wheat cultivars. Initially, the genomic DNA of five grass species (Thinopyrum junceiforme, Th. bessarabicum, Lophopyrum elongatum, Leymus karataviensis and Elytrigia pycnantha) and selected durum cultivars (‘Langdon’, ‘Durox’, ‘Lloyd’, ‘Monroe’, and ‘Medora’) was screened with 40 oligonucleotide primers (nano-mers). Three oligonucleotides that amplified DNA fragments specific to a grass species or to a durum cultivar were identified. Primer PR21 amplified DNA fragments specific to each of the five durum cultivars, and primers PR22 and PR23 amplified fragments specific to each of the grass species. Intergeneric hybrids between the durum cultivars ‘Langdon’, ‘Lloyd’ and ‘Durox’ and Th. junceiforme, and their backcross (BC) progeny were screened with all 40 primers. Six primers amplified parent-specific DNA fragments in the F1 hybrids and their BC1 progeny. Three primers, PR22, PR23 and PR41, that amplified Th. junceiforme DNA fragments in both F1 and BC1 were further analyzed. The presence of an amplified 1.7-kb Th. junceiforme DNA fragment in the F1 hybrids and BC1 progeny was confirmed using Southern analysis by hybridization with both Th. junceiforme genomic DNA and Th. junceiforme DNA amplified with primer PR41. With the exception of line BC1F2 no. 5, five selfed progeny of BC1 and a BC2 of line 3 (BC1F2 no. 3בLloyd’) from a cross of ‘Lloyd’×Th. junceiforme showed the presence of the 1.7-kb DNA fragment. All selfed BC1 and BC2 lines retained the 600-bp fragment that was confirmed after hybridization with Th. junceiforme DNA amplified with primer PR22. Other experiments using RFLP markers also showed the presence of up to seven Th. junceiforme DNA fragments in the F1 hybrids and their BC progeny after hybridization with Th. junceiforme DNA amplified with primer PR41. These studies show the usefulness of molecular markers in detecting alien chromatin/DNA fragments in intergeneric hybrids with durum wheat.
    Type of Medium: Electronic Resource
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