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Genome evolution in alpine oat-like grasses through homoploid hybridization and polyploidy

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ABSTRACT

Molecular cytogenetic and phylogenetic analysis of alpine endemic wild oats of genus Helictotrichon represents a remarkable example of speciation and diversification through homoploid hybridisation and polyploidisation. Results suggest a primary centre of species establishment in the eastern regions of the Alps, with the westward expansion and subsequent ice age interruption resulting in a recently disjunct distribution between populations of the southwestern and southeastern Alps.

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Related in: MedlinePlus

Idiograms of chromosome complements of diploid Helictotrichon species and hexaploid H. sempervirens on a strict consensus tree derived from Topoisomerase IV gene sequences. Bootstrap and Bayesian support are shown on the left and right side above the branches. Chromosomes are numbered below according to their length and arranged into groups of presumable homologues or homoeologues (lines I–VII) according to FISH with 45S and 5S rDNA probes and fluorochrome banding signals. Chromosome bands arranged above or below the chromosomes are subtelomeric, unless an intercalary position is indicated by a square bracket at the side of the respective chromosome. Chromosomes with a NOR bearing the 45 S rDNA bands or chromomycin-positive staining are indicated by a secondary constriction in the chromosome idiogram additional to their centromeric constriction (= satellite chromosomes; cf. Winterfeld and Röser 2007b). Genome-specific DNA and chromosome variants are shown in light blue for H. parlatorei and in pink for H. setaceum. Possible mechanisms of chromosome and genome evolution as well as geographical distribution of the species are listed below. B = B chromosomes.
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plw039-F1: Idiograms of chromosome complements of diploid Helictotrichon species and hexaploid H. sempervirens on a strict consensus tree derived from Topoisomerase IV gene sequences. Bootstrap and Bayesian support are shown on the left and right side above the branches. Chromosomes are numbered below according to their length and arranged into groups of presumable homologues or homoeologues (lines I–VII) according to FISH with 45S and 5S rDNA probes and fluorochrome banding signals. Chromosome bands arranged above or below the chromosomes are subtelomeric, unless an intercalary position is indicated by a square bracket at the side of the respective chromosome. Chromosomes with a NOR bearing the 45 S rDNA bands or chromomycin-positive staining are indicated by a secondary constriction in the chromosome idiogram additional to their centromeric constriction (= satellite chromosomes; cf. Winterfeld and Röser 2007b). Genome-specific DNA and chromosome variants are shown in light blue for H. parlatorei and in pink for H. setaceum. Possible mechanisms of chromosome and genome evolution as well as geographical distribution of the species are listed below. B = B chromosomes.

Mentions: The chromosome sizes, localization of primary constrictions (centromere), secondary constrictions (satellite region; SAT = localization of nucleolus organizer regions, NORs) and extension of chromosome bands (5S rDNA, 45S rDNA, chromomycin and DAPI bands) were measured digitally using Zeiss Axiovision and Adobe PhotoShop 6.0 software. Measurement data was input into Microsoft Excel for calculations. Chromosomes were numbered according to their individual length. Complete chromosome idiograms were constructed using CorelDraw software. In the idiograms the chromosomes were arranged into groups of presumable homologues or homoeologues (indicated by Roman numerals in lines I–VII in Fig. 1) according to FISH and fluorochrome banding signals. Satellite chromosomes representing a secondary constriction, 45S rDNA band or chromomycin positive and DAPI negative bands (cf. Winterfeld and Röser 2007a) were arranged in lines I and II (Fig. 1). The terminology for chromosome shape according to the centromere position (metacentric or submetacentric) followed Levan et al. (1964).Figure 1.


Genome evolution in alpine oat-like grasses through homoploid hybridization and polyploidy
Idiograms of chromosome complements of diploid Helictotrichon species and hexaploid H. sempervirens on a strict consensus tree derived from Topoisomerase IV gene sequences. Bootstrap and Bayesian support are shown on the left and right side above the branches. Chromosomes are numbered below according to their length and arranged into groups of presumable homologues or homoeologues (lines I–VII) according to FISH with 45S and 5S rDNA probes and fluorochrome banding signals. Chromosome bands arranged above or below the chromosomes are subtelomeric, unless an intercalary position is indicated by a square bracket at the side of the respective chromosome. Chromosomes with a NOR bearing the 45 S rDNA bands or chromomycin-positive staining are indicated by a secondary constriction in the chromosome idiogram additional to their centromeric constriction (= satellite chromosomes; cf. Winterfeld and Röser 2007b). Genome-specific DNA and chromosome variants are shown in light blue for H. parlatorei and in pink for H. setaceum. Possible mechanisms of chromosome and genome evolution as well as geographical distribution of the species are listed below. B = B chromosomes.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4940509&req=5

plw039-F1: Idiograms of chromosome complements of diploid Helictotrichon species and hexaploid H. sempervirens on a strict consensus tree derived from Topoisomerase IV gene sequences. Bootstrap and Bayesian support are shown on the left and right side above the branches. Chromosomes are numbered below according to their length and arranged into groups of presumable homologues or homoeologues (lines I–VII) according to FISH with 45S and 5S rDNA probes and fluorochrome banding signals. Chromosome bands arranged above or below the chromosomes are subtelomeric, unless an intercalary position is indicated by a square bracket at the side of the respective chromosome. Chromosomes with a NOR bearing the 45 S rDNA bands or chromomycin-positive staining are indicated by a secondary constriction in the chromosome idiogram additional to their centromeric constriction (= satellite chromosomes; cf. Winterfeld and Röser 2007b). Genome-specific DNA and chromosome variants are shown in light blue for H. parlatorei and in pink for H. setaceum. Possible mechanisms of chromosome and genome evolution as well as geographical distribution of the species are listed below. B = B chromosomes.
Mentions: The chromosome sizes, localization of primary constrictions (centromere), secondary constrictions (satellite region; SAT = localization of nucleolus organizer regions, NORs) and extension of chromosome bands (5S rDNA, 45S rDNA, chromomycin and DAPI bands) were measured digitally using Zeiss Axiovision and Adobe PhotoShop 6.0 software. Measurement data was input into Microsoft Excel for calculations. Chromosomes were numbered according to their individual length. Complete chromosome idiograms were constructed using CorelDraw software. In the idiograms the chromosomes were arranged into groups of presumable homologues or homoeologues (indicated by Roman numerals in lines I–VII in Fig. 1) according to FISH and fluorochrome banding signals. Satellite chromosomes representing a secondary constriction, 45S rDNA band or chromomycin positive and DAPI negative bands (cf. Winterfeld and Röser 2007a) were arranged in lines I and II (Fig. 1). The terminology for chromosome shape according to the centromere position (metacentric or submetacentric) followed Levan et al. (1964).Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

Molecular cytogenetic and phylogenetic analysis of alpine endemic wild oats of genus Helictotrichon represents a remarkable example of speciation and diversification through homoploid hybridisation and polyploidisation. Results suggest a primary centre of species establishment in the eastern regions of the Alps, with the westward expansion and subsequent ice age interruption resulting in a recently disjunct distribution between populations of the southwestern and southeastern Alps.

No MeSH data available.


Related in: MedlinePlus