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  • 1
    ISSN: 1432-2242
    Keywords: Hordeum ; Secale ; Interspecific, intergeneric hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Diploid hybrids between Hordeum chilense and three other species, namely H. vulgare, H. bulbosum and Secale cereale, are described together with the amphidiploid of H. chilensexH. vulgare. Both the diploid hybrid and the amphidiploid of H. chilensexH. vulgare were chromosomally unstable, H. chilensexH. bulbosum was less so, while H. chilensexS. cereale was stable. Differential amphiplasty was found in all combinations. No homoeologous pairing was found in the Hordeum hybrids but in H. chilensexS. cereale there was chromosome pairing both within the two genomes and between the genomes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Hordeum ; chromosome elimination ; chromosome pairing ; genome asynchrony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The C0 tetraploid counterparts of diploid hybrids of Hordeum vulgare × H. bulbosum were meiotically analysed, and were found to be chromosomally less stable than the same genotypes had been as diploids. The 14 bulbosum chromosomes present in the tetraploid cytotypes were probably eliminated as pairs rather than randomly or one genome at the time. Development of the vulgare and bulbosum genomes was asynchronous in some hybrids, the bulbosum chromosomes appearing less advanced than the vulgare chromosomes in the same cell. This appeared to reduce pairing between bulbosum homologues and also suppressed homoeologous pairing.
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  • 3
    ISSN: 1432-2242
    Keywords: Hordeum ; Amphidiploids ; Chromosome elimination ; Chromosome stability ; Gene balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Both diploid and tetraploid hybrids of Hordeum vulgare x H. bulbosum exhibit chromosome instability during plant development and generally lose the H. bulbosum chromosomes by the next generation. However an amphidiploid involving the cultivar ‘Vada’ was found to retain the bulbosum chromosomes through a sexual cycle. Comparisons were made between this stable amphidiploid and a second, unstable amphidiploid involving the cultivar ‘Emir’. At meiosis there was a wide range of chromosome numbers in the ‘Emir’ amphidiploid but only a narrow range in the ‘Vada’ amphidiploid. Degraded chromosomes were commonly found in the PMCs of the ‘Emir’ amphidiploid but none was found in the stable ‘Vada’ amphidiploid. The two amphidiploids were reciprocally crossed and the chromosome numbers of the progeny checked. The H. bulbosum chromosomes had been retained in many of the progeny and both triploid and tetraploid hybrids were found. It is proposed that a gene(s) exists in ‘Vada’ capable of preventing the elimination of bulbosum chromosomes from H. vulgare x H. bulbosum hybrids.
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  • 4
    ISSN: 1432-2242
    Keywords: Hordeum ; Stable hybrids ; Chromosome elimination ; Chromosome stability ; Gene balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hybrid progeny from a stable amphidiploid of H. vulgare x H. bulbosum involving the cultivar ‘Vada’ and an unstable amphidiploid involving the cultivar ‘Emir’ were studied. The genotypes examined contained two genomes from ‘Vada’ or one from ‘Vada’ and one from ‘Emir’, with one or two genomes from H. bulbosum. Comparisons between the chromosome numbers in root-tips and anthers revealed that there was no chromosome elimination in most plants, whether there was one or two Vada genomes present. The one plant in which chromosome elimination was positively identified had ‘Emir’ as opposed to ‘Vada’ cytoplasm. It also had a high incidence of degraded or fragmented chromosomes in the PMCs. Differences in stability between a 27 chromosome plant and other hypotetraploids suggest that ‘Vada’ contains both elimination genes and elimination suppressor genes. Upon selfing, again irrespective of the number of ‘Vada’ genomes present, circa triploid hybrids gave rise to diploid H. vulgare offspring while hypotetraploids produced hybrid-like plants. These included diploids, triploids and tetraploids. There was evidence that suggested that H. vulgare as well as H. bulbosum chromosomes had been eliminated.
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