e-journal

Allotetraploid origin and divergence in Eleusine (Chloridoideae, Poaceae): evidence from low-copy nuclear gene phylogenies and a plastid gene chronogram

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Background and Aims Eleusine (Poaceae) is a small genus of the subfamily Chloridoideae exhibiting considerable morphological and ecological diversity in East Africa and the Americas. The interspecific phylogenetic relationships of Eleusine are investigated in order to identify its allotetraploid origin, and a chronogram is estimated to infer temporal relationships between palaeoenvironment changes and divergence of Eleusine in East Africa.
Methods Two low-copy nuclear (LCN) markers, Pepc4 and EF-1a, were analysed using parsimony, likelihood
and Bayesian approaches. A chronogram of Eleusine was inferred from a combined data set of six plastid DNA
markers (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) using the Bayesian dating method.
Key Results The monophyly of Eleusine is strongly supported by sequence data from two LCN markers. In the
cpDNA phylogeny, three tetraploid species (E. africana, E. coracana and E. kigeziensis) share a common ancestor with the E. indica–E. tristachya clade, which is considered a source of maternal parents for allotetraploids.
Two homoeologous loci are isolated from three tetraploid species in the Pepc4 phylogeny, and the maternal
parents receive further support. The A-type EF-1a sequences possess three characters, i.e. a large number of variations of intron 2; clade E-A distantly diverged from clade E-B and other diploid species; and seven deletions in intron 2, implying a possible derivation through a gene duplication event. The crown age of Eleusine and the allotetraploid lineage are 3.89 million years ago (mya) and 1.40 mya, respectively.
Conclusions The molecular data support independent allotetraploid origins for E. kigeziensis and the
E. africana–E. coracana clade. Both events may have involved diploids E. indica and E. tristachya as the
maternal parents, but the paternal parents remain unidentified. The habitat-specific hypothesis is proposed to explain the divergence of Eleusine and its allotetraploid lineage.
Key words: Allotetraploid origin, chloroplast markers, East Africa, Eleusine, low-copy nuclear markers,
phylogeny, Poaceae.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

: Oxford University Press on behalf of the Annals of Botany Company., 2011

Deskripsi Fisik

Annals of Botany 108: 1287–1298, 2011

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

PERTANIAN.

Info Detail Spesifik

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Pernyataan Tanggungjawab

yuli/agus

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