The cytology of Brachycome lineariloba

Watanabe, Kinzo; Carter, C. R.; Smith-White, S.

doi:10.1007/bf00293131

Cited by 17 publications

(1 citation statement)

References 10 publications

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“…Two such apparent hybrids were confirmed by karyotype analysis and these plants provided little meiotic material, and meiotic configurations seen were extremely complicated. Two configurations identified were a chain of five, two bivalents and one univalent and a complex multivalent association of seven chromosomes (Kyhos et al, 1977).…”

Section: Origin Of B Chromosomes In B Dichromosomaticamentioning

confidence: 99%

The B chromosomes in <i>Brachycome</i>

Leach

Houben

Timmis

2004

Cytogenet Genome Res

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This review presents a historical account of studies of B chromosomes in the genus Brachycome Cass. (synonym: Brachyscome) from the earliest cytological investigations carried out in the late 1960s though to the most recent molecular analyses. Molecular analyses provide insights into the origin and evolution of the B chromosomes (Bs) of Brachycome dichromosomatica, a species which has Bs of two different sizes. The larger Bs are somatically stable whereas the smaller, or micro, Bs are somatically unstable. Both B types contain clusters of ribosomal RNA genes that have been shown unequivocally to be inactive in the case of the larger Bs. The large Bs carry a family of tandem repeat sequences (Bd49) that are located mainly at the centromere. Multiple copies of sequences related to this repeat are present on the A chromosomes (As) of related species, whereas only a few copies exist in the A chromosomes of B. dichromosomatica. The micro Bs share DNA sequences with the As and the larger Bs, and they also have B-specific repeats (Bdm29 and Bdm54). In some cases repeat sequences on the micro Bs have been shown to occur as clusters on the A chromosomes in a proportion of individuals within a population. It is clear that none of these B types originated by simple excision of segments from the A chromosomes.

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Section: Origin Of B Chromosomes In B Dichromosomaticamentioning

confidence: 99%