Tagged: FISH


Stylosanthes hybrid origin

Origin and evolution of the forage allotetraploid species Stylosanthes scabra

The genus Stylosanthes includes nitrogen-fixing and drought-tolerant species of considerable economic importance for perennial pasture, green manure and land recovery. Stylosanthes scabra is adapted to variable soil conditions, being cultivated to improve pastures and soils worldwide. Previous studies have proposed S. scabra as an allotetraploid species (2n = 40) with a putative diploid A genome progenitor S. hamata or S. seabrana (2n = 20) and the B genome progenitor S. viscosa (2n = 20). Cost et al. aimed to provide conclusive evidence for the origin of S. scabra. The authors performed fluorescence in situ hybridization (FISH) and genomic in situ...

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Cariograms showing inter- and intrapopulation site number variation of interstitial telomeric repeats (ITRs) in Anacyclus clavatus.

Variability of interstitial telomeric-like repeats in Mediterranean weedy species

A telomere is the region of DNA that marks the end of a chromosome. The protect the ends of the chromosome, and stop one chromosome from fusing with another. So finding something that looks like a telomere in the middle of a chromosome would be odd – but it happens. And no one knows exactly why. Although interstitial occurrence of telomeric repeat motifs (ITR) has been reported in the genome of a few organisms, the striking level of polymorphism found by Rosata et al. within a single species has not been described before. Rosata and colleagues investigate whether a comparable...

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Multiple target in situ hybridizations combining GISH using H. marinum subsp. gussoneanum DNA as a probe (gusDNA)

Allopolyploidy origins and genome structure of barley relatives

Unravelling relationships within Hordeum, one of the largest genera of the tribe Triticeae (Hordeae), is difficult, as many taxa, including most of the polyploids, are of hybrid origin. Mapping phylogenetic relationships, Cuadrado et al. investigate origins and interspecific affinities of the allotetraploids Hordeum secalinum and H. capense using molecular karyotyping. Genomic in situ hybridization distinguishes the subgenomes Xa and I while FISH/ND-FISH determines the distribution of ten repetitive DNA sequences. Identification of each chromosome pair in the six analysed accessions reveals an intricate pattern of homologous and putative homeologous relationships among barley species carrying the Xa genome. This paper is...

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Evolutionary history of sea barleys (Hordeum marinum)

Evolutionary history of sea barleys (Hordeum marinum)

Hordeum marinum (sea barley) is a complex species that is usually recognized as having two subspecies, marinum (2n = 2x = 14) and gussoneanum (2n = 2x =14 and 2n = 2x = 28). Carmona et al. use comparative physical mapping of repetitive DNA to determine the genome structure of several H. marinum accessions representing all taxa and cytotypes. They detect two subgenomes in the tetraploids, which appear to have come about through a cross between a diploid gussoneanum progenitor and a second, related – but unidentified – diploid ancestor. They conclude that the allopolyploids are segmental in nature with two...

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Molecular cytogenetics of repetitive DNA in jute species

Molecular cytogenetics of repetitive DNA in jute species

The genomes and chromosomes of the important fibre crops white jute and Tossa jute (Corchorus species) are poorly characterized. Information is essential for breeding and improvement, with characters including environmental adaptability, fibre quality and susceptibility to diseases differing between the species. Begum et al. use a comparative analysis of a prominent satelllite DNA family, identified in this study, to reveal its diversification and emerging subfamily structure in both jute genomes, while the heterogenous distribution along chromosomes is conserved. In combination with ribosomal genes and retrotransposon sequences, they use the chromosome-specific distribution of the satellite DNA for in situ hybridization to generate...

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Brassica monosomic alien addition lines

Brassica monosomic alien addition lines

Addition of each chromosome of Brassica oleracea to the chromosome complement of B. rapa results in a series of nine monosomic alien addition lines. Heneen et al. report the development and use of such a series for mapping genes, determining chromosome homoeology, and for assigning genetic linkage groups to specific chromosomes. Seven B. oleracea chromosomes carry major or minor genes controlling seed colour either maternally or through the embryo. Chromosome homoeology prevails largely between chromosomes occupying similar karyotypic positions. The two species are the progenitors of oilseed rape, B. napus, and the results have potential applications in marker-assisted selection and breeding...

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Satellite DNA family in Medicago and allied genera

Satellite DNA family in Medicago and allied genera

Satellite DNA is a genomic component present in virtually all eukaryotic organisms and is an important element in genome organization and evolution in plants. Rosato el al. assess the presence and physical distribution of the repetitive DNA E180 family in 70 accessions from Medicago and allied genera. The results suggest that recurrent and independent evolutionary episodes of amplification appear to have been produced in both annual and perennial Medicago species as well as in basal and derived clades, and hence the use of repetitive DNA families as phylogenetic markers in this genus should be viewed with caution.

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