Diversity and Linkage of Genes in the Self-Incompatibility Gene Family in Arabidopsis lyrata

Corresponding author: Deborah Charlesworth, Animal and Population Biology, University of Edinburgh, Ashworth Laboratories, King's Bldgs., West Mains Rd., Edinburgh EH9 3JT, United Kingdom., deborah.charlesworth{at}ed.ac.uk (E-mail)

Communicating editor: M. K. UYENOYAMA

We report studies of seven members of the S-domain gene family in Arabidopsis lyrata, a member of the Brassicaceae that has a sporophytic self-incompatibility (SI) system. Orthologs for five loci are identifiable in the self-compatible relative A. thaliana. Like the Brassica stigmatic incompatibility protein locus (SRK), some of these genes have kinase domains. We show that several of these genes are unlinked to the putative A. lyrata SRK, Aly13. These genes have much lower nonsynonymous and synonymous polymorphism than Aly13 in the S-domains within natural populations, and differentiation between populations is higher, consistent with balancing selection at the Aly13 locus. One gene (Aly8) is linked to Aly13 and has high diversity. No departures from neutrality were detected for any of the loci. Comparing different loci within A. lyrata, sites corresponding to hypervariable regions in the Brassica S-loci (SLG and SRK) and in comparable regions of Aly13 have greater replacement site divergence than the rest of the S-domain. This suggests that the high polymorphism in these regions of incompatibility loci is due to balancing selection acting on sites within or near these regions, combined with low selective constraints.

This article has been cited by other articles:

				S. Takuno, T. Nishio, Y. Satta, and H. Innan Preservation of a Pseudogene by Gene Conversion and Diversifying Selection Genetics, September 1, 2008; 180(1): 517 - 531. [Abstract] [Full Text] [PDF]

				S. Kubota, Y. Kameyama, A. S. Hirao, and M. Ohara Adaptive significance of self-fertilization in a hermaphroditic perennial, Trillium camschatcense (Melanthiaceae) Am. J. Botany, April 1, 2008; 95(4): 482 - 489. [Abstract] [Full Text] [PDF]

				J. W. Busch, J. Sharma, and D. J. Schoen Molecular Characterization of Lal2, an SRK-Like Gene Linked to the S-Locus in the Wild Mustard Leavenworthia alabamica Genetics, April 1, 2008; 178(4): 2055 - 2067. [Abstract] [Full Text] [PDF]

				E. Kamau, B. Charlesworth, and D. Charlesworth Linkage Disequilibrium and Recombination Rate Estimates in the Self-Incompatibility Region of Arabidopsis lyrata Genetics, August 1, 2007; 176(4): 2357 - 2369. [Abstract] [Full Text] [PDF]

				J. S. Bechsgaard, V. Castric, D. Charlesworth, X. Vekemans, and M. H. Schierup The Transition to Self-Compatibility in Arabidopsis thaliana and Evolution within S-Haplotypes over 10 Myr Mol. Biol. Evol., September 1, 2006; 23(9): 1741 - 1750. [Abstract] [Full Text] [PDF]

				J. Hagenblad, J. Bechsgaard, and D. Charlesworth Linkage Disequilibrium Between Incompatibility Locus Region Genes in the Plant Arabidopsis lyrata Genetics, June 1, 2006; 173(2): 1057 - 1073. [Abstract] [Full Text] [PDF]

				D. Charlesworth, E. Kamau, J. Hagenblad, and C. Tang Trans-specificity at Loci Near the Self-Incompatibility Loci in Arabidopsis Genetics, April 1, 2006; 172(4): 2699 - 2704. [Abstract] [Full Text] [PDF]

				C. K. Raymond, A. Kas, M. Paddock, R. Qiu, Y. Zhou, S. Subramanian, J. Chang, A. Palmieri, E. Haugen, R. Kaul, et al. Ancient haplotypes of the HLA Class II region Genome Res., September 1, 2005; 15(9): 1250 - 1257. [Abstract] [Full Text] [PDF]

				N. L. Prigoda, A. Nassuth, and B. K. Mable Phenotypic and Genotypic Expression of Self-incompatibility Haplotypes in Arabidopsis lyrata Suggests Unique Origin of Alleles in Different Dominance Classes Mol. Biol. Evol., July 1, 2005; 22(7): 1609 - 1620. [Abstract] [Full Text] [PDF]

				K. K. Shimizu, J. M. Cork, A. L. Caicedo, C. A. Mays, R. C. Moore, K. M. Olsen, S. Ruzsa, G. Coop, C. D. Bustamante, P. Awadalla, et al. Darwinian Selection on a Selfing Locus Science, December 17, 2004; 306(5704): 2081 - 2084. [Abstract] [Full Text] [PDF]

				K. M. Teshima and H. Innan The Effect of Gene Conversion on the Divergence Between Duplicated Genes Genetics, March 1, 2004; 166(3): 1553 - 1560. [Abstract] [Full Text] [PDF]