Research article summary (published 23 Jul 2009):

Comparative cytogenetic analysis of the genomes of the model grass Brachypodium distachyon and its close relatives.

Full Abstract

BACKGROUND AND AIMS: Brachypodium is a small genus of temperate grasses that comprises 12-15 species. Brachypodium distachyon is now well established as a model species for temperate cereals and forage grasses. In contrast to B. distachyon, other members of the genus have been poorly investigated at the chromosome level or not at all. METHODS: Twenty accessions comprising six species and two subspecies of Brachypodium were analysed cytogenetically. Measurements of nuclear genome size were made by flow cytometry. Chromosomal localization of 18-5.8-25S rDNA and 5S rDNA loci was performed by dual-colour fluorescence in situ hybridization (FISH) on enzymatically digested root-tip meristematic cells. For comparative phylogenetic analyses genomic in situ hybridization (GISH) applied to somatic chromosome preparations was used. KEY RESULTS: All Brachypodium species examined have rather small genomes and chromosomes. Their chromosome numbers and genome sizes vary from 2n = 10 and 0.631 pg/2C in B. distachyon to 2n = 38 and 2.57 pg/2C in B. retusum, respectively. Genotypes with 18 and 28 chromosomes were found among B. pinnatum accessions. GISH analysis revealed that B. pinnatum with 28 chromosomes is most likely an interspecific hybrid between B. distachyon (2n = 10) and B. pinnatum (2n = 18). Two other species, B. phoenicoides and B. retusum, are also allopolyploids and B. distachyon or a close relative seems to be one of their putative ancestral species. In chromosomes of all species examined the 45S rDNA loci are distally distributed whereas loci for 5S rDNA are pericentromeric. CONCLUSIONS: The increasing significance of B. distachyon as a model grass emphasizes the need to understand the evolutionary relationships in the genus Brachypodium and to ensure consistency in the biological nomenclature of its species. Modern molecular cytogenetic techniques such as FISH and GISH are suitable for comparative phylogenetic analyses and may provide informative chromosome- and/or genome-specific landmarks.

Author information

Author/s: Wolny, Elzbieta (E); Hasterok, Robert (R);

Affiliation: Department of Plant Anatomy and Cytology, University of Silesia, Jagiellonska 28, 40-032 Katowice, Poland.

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Annals of botany (Ann Bot), published in England. (Language: eng)

Reference: 2009-Oct; vol 104 (issue 5) : pp 873-81

Dates: Created 2009/09/24; Completed 2009/11/02;

PMID: 19633311, status: MEDLINE (last retrieval date: 11/2/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Chromosomes, Plant - genetics DNA, Plant - genetics Flow Cytometry Genome, Plant - genetics

In Situ Hybridization, Fluorescence Phylogeny Poaceae - genetics RNA, Ribosomal - genetics

Associated Chemicals: DNA, Plant (0) ; RNA, Ribosomal (0)

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