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Phylogenetic analysis of Hordeum (Poaceae) as inferred by nuclear rDNA ITS sequences
- Source :
- Molecular phylogenetics and evolution. 33(2)
- Publication Year :
- 2003
-
Abstract
- Hordeum (Poaceae, Triticeae) occurs with 31 species worldwide in temperate regions, with the exception of Australasia. About 50% of the species are polyploids (4x, 6x) or occur as di- and polyploid forms. To analyze the phylogenetic relationships among diploid and polyploid taxa of the genus the nuclear rDNA internal transcribed spacer region (ITS) was analyzed for 91 accessions, representing all Hordeum species, together with 10 outgroup species. PCR products were either directly sequenced (outgroups) or cloned and eight clones per individual were analyzed. Phylogenetic analysis revealed four major clades that concur with the four genome groups in Hordeum (H, I, Xa, and Xu). Allopolyploids, putative autopolyploids, and species groups within the closely related H-genome clade could be identified. The ITS data indicate times of independent evolution of paralogous rDNA clusters on different chromosomes intermitted by sweeps of homogenization among these clusters and bi-directional homogenization of the clusters in diploids. Penalized likelihood analysis revealed an age of about 12 million years (my) for the genus and indicated the start of a rapid radiation in the H-genome group about 2.5 my ago in South America and Asia.
- Subjects :
- Genetics
Cell Nucleus
Phylogenetic tree
biology
fungi
food and beverages
Hordeum
biology.organism_classification
DNA, Ribosomal
Evolution, Molecular
Polyploidy
Polyploid
Phylogenetics
DNA, Ribosomal Spacer
Internal transcribed spacer
Ploidy
Triticeae
Clade
Molecular Biology
Ecology, Evolution, Behavior and Systematics
Phylogeny
Subjects
Details
- ISSN :
- 10557903
- Volume :
- 33
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- Molecular phylogenetics and evolution
- Accession number :
- edsair.doi.dedup.....40f52c2ebb04e248a1e82ca6b705e1f3