Cytogenetics of Polyploids

Jackson, R. C.; Casey, Jane

doi:10.1007/978-1-4613-3069-1_2

Cited by 34 publications

(17 citation statements)

References 51 publications

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“…There is no reason why the genomes of polyploids should be immune from such changes. Indeed in view of the inevitable duplication of many DNA sequences in polyploids, they may be more tolerant of and, therefore, more prone to variation in DNA content than diploids (Jackson and Casey, 1980). It seems then that the DNA content of a genome is not immutable and so its value in tracing the ancestry of polyploids is somewhat diminished.…”

Section: Methodsmentioning

confidence: 99%

DNA variation in Festuca

Seal

1983

Heredity

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SUMMARYThere is substantial interspecific variation in nuclear DNA content in Festuca much of which cannot be accounted for by variation in chromosome number.The distribution of species DNA contents closely matches the taxonomic divisions within the genus. Polyploid taxa, especially high polyploids, tend to have less DNA than expected.(a) There may be errors in the proposed modes of origin of polyploid forms. In particular, the distinction between European and Moroccan forms may have been underestimated, and/or (b) polyploid species may have undergone a reduction in nuclear DNA content since their divergence, relative to their progenitor species of lower ploidy.

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Section: Methodsmentioning

confidence: 99%

DNA variation in Festuca

Seal

1983

Heredity

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“…In contrast to this phenomenon the model described by Jackson & Casey (1982) indicates that all the specimens TABLE 3.__Comparison between observed chromosome configurations and the expected chromosome configurations in triploids according to the methods described by Alonso & Kimber (1981), Jackson & Casey (1980 and Jackson & H auber( 1982). Only the model with the lowest average sum of squares is given in this table studied are autotetraploids with 0-2 chiasmata per chro mosome pair and with partly random chromosome asso ciations.…”

Section: Chromosome Behaviourmentioning

confidence: 99%

“…The hybrid index also indicates that R. longepedicellatus and R. cuneifolius B are clearly separated morphologically. However, a continuous bridge of morphological charac ters spans the gap between them in the form of the very variable hybrid species, R. x proteus (Figures 1, 2, 3 & Jackson & Casey (1980 Jackson & Casey (1980 and Jackson& H auber (1982).…”

Section: Morphologymentioning

confidence: 99%

“…These methods included the genomic relationship system developed by Kimber and others (Kimber & Hulse 1978;Driscoll 1979;Driscoll, Bielig & Darvey 1979;Alonso & Kimber 1981;Espinasse & Kimber 1981;Kimber & Alonso 1981;Kimber, Alonso & Sallee 1981;Alonso & Kimber 1984), the binomial system de veloped by Jackson et al (Jackson & Casey 1980Jackson & Hauber 1982) and the modification of this binomial system by Spies (1984). Computer pro grammes were used to calculate these values.…”

Section: Introductionmentioning

confidence: 99%

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The genus Rubus (Rosaceae) in South Africa. IV. Natural hybridiza tion

Spies¹,

Stirton

Plessis³

1987

Bothalia

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“…The chromosome behavior during meiosis is usually examined to determine the numerical and structural features of chromosomes. The configuration at metaphase I (MI) of meiosis is commonly showing the homologous degree between the different sets of chromosomes in polyploid plants (Jackson and Casey 1980). Further comparative analysis helps to explore the way of formation and evolution mode of the polyploidy.…”

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confidence: 99%

Cytological Study of Tetraploid Species of <i>Magnolia</i> subgenus <i>Yulania</i> (Magnoliaceae)

Wang

Ejder

et al. 2016

CYTOLOGIA

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Summary Cytological studies were conducted on five tetraploid species plus two varieties of Magnolia subgenus Yulania and a hybrid between two of these species. Two different chromosome configurations in meiosis are observed in this article. The first group was typical for M. acuminata, M. liliiflora and their relatives which share several cytological characteristics including chromosome configurations and behavior in meiosis. The cytological evidence indicate autotetraploid origin for these species, despite the homologous chromosomes likely having changed their structures causing the formation of heteromorphic multivalents, chromosome bridges and fragments during meiosis. The second group of chromosome configuration was found in M. cylindrica and M. concinna. These species were characterized by very rare trivalents and tetravalents. These observations suggest these taxa as allotetraploids which may have been formed from hybridisation between hexaploid and diploid parents as deduced from trivalents observed at some rate. Multivalent formation and possible translocations and inversions of chromosomes in M. liliiflora influence its propagation by causing low fertility. M. liliiflora is probably a comparatively new species with an unstable chromosome constitution and is growing only in small populations at low elevation. It is vulnerable, and the species could already be extinct in nature. On the other hand, M. acuminata shows a more regular chromosome behavior and fewer abortion spores than M. liliiflora, and should be a more stable species with longer evolution time. Thus, the superior fertility of M. acuminata has enabled it to develop a stable and extensive distribution from NE to SE USA.

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Cytogenetics of Polyploids

Cited by 34 publications

References 51 publications

DNA variation in Festuca

DNA variation in Festuca

The genus Rubus (Rosaceae) in South Africa. IV. Natural hybridiza tion

Cytological Study of Tetraploid Species of <i>Magnolia</i> subgenus <i>Yulania</i> (Magnoliaceae)

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Cytogenetics of Polyploids

Cited by 34 publications

References 51 publications

DNA variation in Festuca

DNA variation in Festuca

The genus Rubus (Rosaceae) in South Africa. IV. Natural hybridiza­ tion

Cytological Study of Tetraploid Species of <i>Magnolia</i> subgenus <i>Yulania</i> (Magnoliaceae)

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The genus Rubus (Rosaceae) in South Africa. IV. Natural hybridiza tion