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DNA polymorphism, haplotype structure and balancing selection in the Leavenworthia PgiC locus
1Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom. dmitry.filatov@ed.ac.uk
Genetics
|November 5, 1999
Summary
Balancing selection maintains distinct DNA haplotypes in the cytosolic phosphoglucose isomerase (PGI) gene of Leavenworthia mustard species. These ancient haplotypes predate species divergence and persist due to balancing selection, not population structure.
Area of Science:
- * Evolutionary genetics
- * Molecular evolution
- * Plant genomics
Background:
- * Cytosolic phosphoglucose isomerase (PGI) is a key enzyme in carbohydrate metabolism.
- * DNA polymorphism and divergence studies are crucial for understanding evolutionary processes.
- * The mustard genus Leavenworthia provides a model system for studying plant evolution.
Purpose of the Study:
- * To investigate DNA polymorphism and divergence within the PgiC gene of five Leavenworthia species.
- * To determine the evolutionary forces shaping genetic variation at this locus.
- * To explore the role of balancing selection in maintaining genetic diversity.
Main Methods:
- * Sequencing of a 2.3-kb PgiC gene region (exons 6-16) from multiple individuals across five Leavenworthia species.
- * Analysis of nucleotide polymorphism, recombination rates, and haplotype structure.
- * Application of population genetic tests (e.g., Kelly's Z(nS), Wall's B and Q) to infer selective pressures.
Main Results:
- * High nucleotide polymorphism observed in the L. stylosa PgiC gene (pi = 0.051, theta = 0.052).
- * Extensive haplotype structure detected despite high recombination rates.
- * Haplotype divergence predates species divergence, with haplotypes segregating across multiple species.
Conclusions:
- * Balancing selection is the likely mechanism maintaining ancient, divergent haplotypes at the PgiC locus in Leavenworthia.
- * Population subdivision does not explain the observed haplotype structure.
- * The PgiC gene region is a valuable target for studying balancing selection in plants.
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