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Pericentromeric recombination suppression and the 'large X effect' in plants
Edgar L Y Wong1,2, Dmitry A Filatov3
1Department of Biology, University of Oxford, Oxford, UK.
Scientific Reports
|December 8, 2023
Summary
The large X effect (LXE), a barrier to species isolation, is primarily caused by suppressed recombination on the X chromosome in plants like Silene latifolia. This lack of genetic exchange prevents gene flow between closely related species.
Area of Science:
- Evolutionary Biology
- Genetics
- Plant Science
Background:
- The 'large X' effect (LXE) is a phenomenon where the X chromosome significantly contributes to reproductive isolation between species.
- The leading hypothesis for LXE involves recessive incompatibilities in hemizygous X-linked genes, but this doesn't explain LXE in species with recently evolved sex chromosomes.
Purpose of the Study:
- To investigate the cause of LXE in the plant species Silene latifolia, which has a large, rarely recombining pericentromeric region on its X chromosome (Xpr).
- To test the hypothesis that recombination suppression on the X chromosome is the primary driver of LXE in S. latifolia and S. dioica.
Main Methods:
- Genome-wide analysis of DNA polymorphism in S. latifolia and S. dioica.
- Analysis of gene expression in both species.
- Genetic mapping to identify non-recombining regions on the X chromosome.
Main Results:
- Rarely recombining regions on the X chromosome were found to be a significant barrier to interspecific gene flow.
- Little evidence was found for other factors contributing to LXE.
- Extensive pericentromeric recombination suppression on the X chromosome appears to be the main cause of LXE.
Conclusions:
- Recombination suppression on the X chromosome is the primary mechanism driving the 'large X' effect in Silene species.
- This finding challenges previous hypotheses and highlights the role of chromosomal architecture in speciation.
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