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Concerted evolution in the ribosomal RNA cistron
Kershney Naidoo1, Emma T Steenkamp, Martin P A Coetzee
1Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Faculty of Natural and Agricultural Sciences, Pretoria, South Africa.
Plos One
|April 5, 2013
Summary
Unequal crossing over drives gene conversion and homogenization in fungal ribosomal DNA. This process, crucial for preventing mutations in gene clusters, occurs more frequently during meiosis than mitosis in Ceratocystis manginecans.
Area of Science:
- Molecular Biology
- Evolutionary Genetics
- Mycology
Background:
- Gene conversion homogenizes multigene families, preventing mutations in clustered genes.
- Recombination during meiosis is hypothesized to drive concerted evolution.
- The specific role of unequal crossing over in gene conversion remains unclear.
Purpose of the Study:
- To investigate the role of unequal crossing over in gene conversion within the ribosomal RNA cistron.
- To determine if gene conversion occurs during meiosis, mitosis, or both life stages in Ceratocystis manginecans.
- To test the hypothesis that unequal crossing over significantly contributes to homogenization.
Main Methods:
- Analyzing two distinct internal transcribed spacer (ITS) sequences in the ribosomal RNA cistron of Ceratocystis manginecans.
- Utilizing Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) assays to differentiate ITS types.
- Employing chi-square analyses to assess the statistical significance of changes in ITS type ratios.
Main Results:
- Observed significant changes in the relative ratios of the two ITS sequence types.
- These changes occurred during both vegetative (mitotic) culturing and sexual reproduction (meiosis).
- The rate of change in ITS type ratios was notably higher during meiosis compared to mitosis.
Conclusions:
- Provided concrete evidence supporting homogenization in the ribosomal RNA gene clusters of Ceratocystis manginecans.
- Concluded that unequal crossing over is the most plausible mechanism driving this homogenization process.
- Highlighted the significant role of meiosis in facilitating gene conversion and maintaining sequence homogeneity.
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