Journal Article

Distribution and diversity of cytotypes in <i>Dianthus broteri</i> as evidenced by genome size variations

Francisco Balao, Ramón Casimiro-Soriguer, María Talavera, Javier Herrera and Salvador Talavera

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 104, issue 5, pages 965-973
Published in print October 2009 | ISSN: 0305-7364
Published online July 2009 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcp182
Distribution and diversity of cytotypes in Dianthus broteri as evidenced by genome size variations

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Studying the spatial distribution of cytotypes and genome size in plants can provide valuable information about the evolution of polyploid complexes. Here, the spatial distribution of cytological races and the amount of DNA in Dianthus broteri, an Iberian carnation with several ploidy levels, is investigated.

Methods

Sample chromosome counts and flow cytometry (using propidium iodide) were used to determine overall genome size (2C value) and ploidy level in 244 individuals of 25 populations. Both fresh and dried samples were investigated. Differences in 2C and 1Cx values among ploidy levels within biogeographical provinces were tested using ANOVA. Geographical correlations of genome size were also explored.

Key Results

Extensive variation in chromosomes numbers (2n = 2x = 30, 2n = 4x = 60, 2n = 6x = 90 and 2n = 12x =180) was detected, and the dodecaploid cytotype is reported for the first time in this genus. As regards cytotype distribution, six populations were diploid, 11 were tetraploid, three were hexaploid and five were dodecaploid. Except for one diploid population containing some triploid plants (2n = 45), the remaining populations showed a single cytotype. Diploids appeared in two disjunct areas (south-east and south-west), and so did tetraploids (although with a considerably wider geographic range). Dehydrated leaf samples provided reliable measurements of DNA content. Genome size varied significantly among some cytotypes, and also extensively within diploid (up to 1·17-fold) and tetraploid (1·22-fold) populations. Nevertheless, variations were not straightforwardly congruent with ecology and geographical distribution.

Conclusions

Dianthus broteri shows the highest diversity of cytotypes known to date in the genus Dianthus. Moreover, some cytotypes present remarkable internal genome size variation. The evolution of the complex is discussed in terms of autopolyploidy, with primary and secondary contact zones.

Keywords: Autopolyploidy; Caryophyllaceae; chromosome numbers; contact zones; dried leaves; dodecaploid; flow cytometry; Mediterranean; propidium iodide; refugia

Journal Article.  6083 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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