e-journal

Evolution of genome size in Carex (Cyperaceae) in relation to chromosome number and genomic base composition

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† Background and Aims:
The genus Carex exhibits karyological peculiarities related to holocentrism, specifically extremely broad and almost continual variation in chromosome number. However, the effect of these peculiarities on the evolution of the genome (genome size, base composition) remains unknown. While in monocentrics, determining the arithmetic relationship between the chromosome numbers of related species is usually sufficient for the detection of particular modes of karyotype evolution (i.e. polyploidy and dysploidy), in holocentrics where
chromosomal fission and fusion occur such detection requires knowledge of the DNA content.

† Methods:
The genome size and GC content were estimated in 157 taxa using flow cytometry. The exact chromosome numbers were known for 96 measured samples and were taken from the available literature for other taxa. All relationships were tested in a phylogenetic framework using the ITS tree of 105 species.

† Key Results:
The 1C genome size varied between 0.24 and 1.64 pg in Carex secalina and C. cuspidata, respectively. The genomic GC content varied from 34.8 % to 40.6 % from C. secalina to C. firma. Both genomic parameters were positively correlated. Seven polyploid and two potentially polyploid taxa were detected in the core Carex clade. A strong negative correlation between genome size and chromosome number was documented in non-polyploid taxa. Non-polyploid taxa of the core Carex clade exhibited a higher rate of genome-size evolution
compared with the Vignea clade. Three dioecious taxa exhibited larger genomes, larger chromosomes, and a
higher GC content than their hermaphrodite relatives.

†Conclusions:
Genomes of Carex are relatively small and very GC-poor compared with other angiosperms. We conclude that the evolution of genome and karyotype in Carex is promoted by frequent chromosomal fissions/fusions, rare polyploidy and common repetitive DNA proliferation/removal.

Key words: Agmatoploidy, AT/GC ratio, chromosomal fusion and fission, chromosome numbers, DNA content,
flow cytometry, GC content, karyotype, phylogeny, polyploidy, symploidy.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2013

Deskripsi Fisik

Annals of Botany 111: 79–94, 2013

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

EKOFISIOLOGI TANAMAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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