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Evidence for a Common Origin of Homomorphic and Heteromorphic Sex Chromosomes in Distinct Spinacia Species.

Fujito S, Takahata S, Suzuki R, Hoshino Y, Ohmido N, Onodera Y - G3 (Bethesda) (2015)

Bottom Line: In this study, nuclear and chloroplast sequences from 21 accessions of Spinacia germplasm and six spinach cultivars or lines were subjected to phylogenetic analysis to define the relationships among the three species.Group 2 also was characterized by a sexual dimorphism in inflorescence structure, which was not observed in Group 1.Our data suggest that the Spinacia genus may serve as a good model for investigation of evolutionary mechanisms underlying the emergence of heteromorphic sex chromosome pairs from ancestral homomorphic pairs.

View Article: PubMed Central - PubMed

Affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan.

No MeSH data available.


Related in: MedlinePlus

Mitotic metaphase chromosomes in S. oleracea L. Mazeran and S. tetrandra Stev. PI 647859. (A–D) 4′,6-diamidino-2-phenylindole (DAPI)-stained metaphase chromosomes of S. oleracea L. Mazeran (A, male; B, female) and S. tetrandra Stev. PI 647859 (C, male; D, female). The Arabic numerals next to chromosomes represent the chromosome number. The sex chromosomes of S. tetrandra Stev. are denoted by X and Y. Positions of satellites (SAT) are indicated by arrows. (A′–D′) Fluorescence in situ hybridization mapping of 45S (FITC, green) and 5S (Cy3, red) rDNA loci on metaphase chromosomes of S. oleracea L. Mazeran (A′, male; B′, female) and S. tetrandra Stev. PI 647859 (C′, male; D′, female). Triangles and arrows show the locations of 45S and 5S rDNA loci. Bars = 5 µm.
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fig3: Mitotic metaphase chromosomes in S. oleracea L. Mazeran and S. tetrandra Stev. PI 647859. (A–D) 4′,6-diamidino-2-phenylindole (DAPI)-stained metaphase chromosomes of S. oleracea L. Mazeran (A, male; B, female) and S. tetrandra Stev. PI 647859 (C, male; D, female). The Arabic numerals next to chromosomes represent the chromosome number. The sex chromosomes of S. tetrandra Stev. are denoted by X and Y. Positions of satellites (SAT) are indicated by arrows. (A′–D′) Fluorescence in situ hybridization mapping of 45S (FITC, green) and 5S (Cy3, red) rDNA loci on metaphase chromosomes of S. oleracea L. Mazeran (A′, male; B′, female) and S. tetrandra Stev. PI 647859 (C′, male; D′, female). Triangles and arrows show the locations of 45S and 5S rDNA loci. Bars = 5 µm.

Mentions: To confirm the homomorphism of the sex chromosome pair of Group 1 plants indicated by our flow cytometric analysis, we observed mitotic chromosomes in root tip cells prepared from male and female S. oleracea L. Mazeran plants. Using microscope observations of metaphase and prometaphase spreads, we confirmed the presence of 2n = 12 chromosomes in both male and female spinach plants (Figure 3 and Figure S6). We did not observe an obvious morphologic difference between members of each chromosomal pair for either sex. We determined the relative length and the arm length ratio of the spinach chromosomes by examining six metaphase spreads from three male and three female plants (Table 3). The chromosome complement of spinach was composed of two pairs of submedian chromosomes and four pairs of subterminal chromosomes, consistent with previous reports (Ellis and Janick 1960; Ito et al. 2000). Based on a comparison between our data and that of Ito et al. (2000), the chromosomes were numbered 1 through 6 (Table 3 and Table S3). We observed the frequent occurrence of satellites during prometaphase on Chromosomes 5 and 6 (Figure S6 and Table 3). As shown in Figure 3, we also observed a satellite on Chromosome 5 in a metaphase spread. These results agree with Sugiyama and Suto (1964), though other studies have reported a satellite on Chromosome 5 but not on Chromosome 6 (Ellis and Janick 1960; Ito et al. 2000) (Table S3).


Evidence for a Common Origin of Homomorphic and Heteromorphic Sex Chromosomes in Distinct Spinacia Species.

Fujito S, Takahata S, Suzuki R, Hoshino Y, Ohmido N, Onodera Y - G3 (Bethesda) (2015)

Mitotic metaphase chromosomes in S. oleracea L. Mazeran and S. tetrandra Stev. PI 647859. (A–D) 4′,6-diamidino-2-phenylindole (DAPI)-stained metaphase chromosomes of S. oleracea L. Mazeran (A, male; B, female) and S. tetrandra Stev. PI 647859 (C, male; D, female). The Arabic numerals next to chromosomes represent the chromosome number. The sex chromosomes of S. tetrandra Stev. are denoted by X and Y. Positions of satellites (SAT) are indicated by arrows. (A′–D′) Fluorescence in situ hybridization mapping of 45S (FITC, green) and 5S (Cy3, red) rDNA loci on metaphase chromosomes of S. oleracea L. Mazeran (A′, male; B′, female) and S. tetrandra Stev. PI 647859 (C′, male; D′, female). Triangles and arrows show the locations of 45S and 5S rDNA loci. Bars = 5 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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fig3: Mitotic metaphase chromosomes in S. oleracea L. Mazeran and S. tetrandra Stev. PI 647859. (A–D) 4′,6-diamidino-2-phenylindole (DAPI)-stained metaphase chromosomes of S. oleracea L. Mazeran (A, male; B, female) and S. tetrandra Stev. PI 647859 (C, male; D, female). The Arabic numerals next to chromosomes represent the chromosome number. The sex chromosomes of S. tetrandra Stev. are denoted by X and Y. Positions of satellites (SAT) are indicated by arrows. (A′–D′) Fluorescence in situ hybridization mapping of 45S (FITC, green) and 5S (Cy3, red) rDNA loci on metaphase chromosomes of S. oleracea L. Mazeran (A′, male; B′, female) and S. tetrandra Stev. PI 647859 (C′, male; D′, female). Triangles and arrows show the locations of 45S and 5S rDNA loci. Bars = 5 µm.
Mentions: To confirm the homomorphism of the sex chromosome pair of Group 1 plants indicated by our flow cytometric analysis, we observed mitotic chromosomes in root tip cells prepared from male and female S. oleracea L. Mazeran plants. Using microscope observations of metaphase and prometaphase spreads, we confirmed the presence of 2n = 12 chromosomes in both male and female spinach plants (Figure 3 and Figure S6). We did not observe an obvious morphologic difference between members of each chromosomal pair for either sex. We determined the relative length and the arm length ratio of the spinach chromosomes by examining six metaphase spreads from three male and three female plants (Table 3). The chromosome complement of spinach was composed of two pairs of submedian chromosomes and four pairs of subterminal chromosomes, consistent with previous reports (Ellis and Janick 1960; Ito et al. 2000). Based on a comparison between our data and that of Ito et al. (2000), the chromosomes were numbered 1 through 6 (Table 3 and Table S3). We observed the frequent occurrence of satellites during prometaphase on Chromosomes 5 and 6 (Figure S6 and Table 3). As shown in Figure 3, we also observed a satellite on Chromosome 5 in a metaphase spread. These results agree with Sugiyama and Suto (1964), though other studies have reported a satellite on Chromosome 5 but not on Chromosome 6 (Ellis and Janick 1960; Ito et al. 2000) (Table S3).

Bottom Line: In this study, nuclear and chloroplast sequences from 21 accessions of Spinacia germplasm and six spinach cultivars or lines were subjected to phylogenetic analysis to define the relationships among the three species.Group 2 also was characterized by a sexual dimorphism in inflorescence structure, which was not observed in Group 1.Our data suggest that the Spinacia genus may serve as a good model for investigation of evolutionary mechanisms underlying the emergence of heteromorphic sex chromosome pairs from ancestral homomorphic pairs.

View Article: PubMed Central - PubMed

Affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Sapporo 060-8589, Japan.

No MeSH data available.


Related in: MedlinePlus