Journal article
Karyotype polymorphism and chromosomal rearrangement in populations of the phytopathogenic fungus, Ascochyta rabiei
Fungal biology, Vol.116(11), pp.1119-1133
11/2012
Handle:
https://hdl.handle.net/2376/108681
PMID: 23153803
Abstract
The fungus Ascochyta rabiei is the causal agent of Ascochyta blight of chickpea and the most serious threat to chickpea production. Little is currently known about the genome size or organization of A. rabiei. Given recent genome sequencing efforts, characterization of the genome at a population scale will provide a framework for genome interpretation and direction of future resequencing efforts. Electrophoretic karyotype profiles of 112 isolates from 21 countries revealed 12–16 chromosomes between 0.9 Mb and 4.6 Mb with an estimated genome size of 23 Mb–34 Mb. Three general karyotype profiles A, B, and C were defined by the arrangement of the largest chromosomes. Approximately one-third of isolates (group A) possessed a chromosome larger than 4.0 Mb that was absent from group B and C isolates. The ribosomal RNA gene (rDNA) cluster was assigned to the largest chromosome in all except four isolates (group C) whose rDNA cluster was located on the second largest chromosome (3.2 Mb). Analysis of progeny from an in vitro sexual cross between two group B isolates revealed one of 16 progeny with an rDNA-encoding chromosome larger than 4.0 Mb similar to group A isolates, even though a chromosome of this size was not present in either parent. No expansion of the rDNA cluster was detected in the progeny, indicating the increase in chromosome size was not due to an expansion in number of rDNA repeats. The karyotype of A. rabiei is relatively conserved when compared with published examples of asexual ascomycetes, but labile with the potential for large scale chromosomal rearrangements during meiosis. The results of this study will allow for the targeted sequencing of specific isolates to determine the molecular mechanisms of karyotype variation within this species.
► Population wide Ascochyta rabiei genome karyotype analysis. ► Genome structure and organization as determined with karyotype analysis. ► Two predominant A. rabiei karyotype profiles were identified. ► Chromosome size change occurs independently of rDNA copy number in A. rabiei. ► We also present karyotype profiles for four other closely related Ascochyta spp.
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Details
- Title
- Karyotype polymorphism and chromosomal rearrangement in populations of the phytopathogenic fungus, Ascochyta rabiei
- Creators
- Hajime O Akamatsu - Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USAMartin I Chilvers - Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USAWalter J Kaiser - 3394 Chickory Way, Boise, ID 83706, USATobin L Peever - Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA
- Publication Details
- Fungal biology, Vol.116(11), pp.1119-1133
- Academic Unit
- Plant Pathology, Department of
- Publisher
- Elsevier Ltd
- Identifiers
- 99900547160701842
- Language
- English
- Resource Type
- Journal article