Polymorphism at the self-incompatibility locus in Solanaceae predates speciation

Thomas R. Ioerger, Andrew G. Clark, Teh-hui Kao

Research output: Contribution to journalArticle

214 Citations (Scopus)

Abstract

Sequences of 11 alleles of the gametophytic self-incompatibility locus (S locus) from three species of the Solanaceae family have recently been determined. Pairwise comparisons of these alleles reveal two unexpected observations: (i) amino acid sequence similarity can be as low as 40% within species and (ii) some interspecific similarities are higher than intraspecific similarities. The gene genealogy clearly illustrates this unusual pattern of relationships. The data suggest that some of the polymorphism at the S locus existed prior to the divergence of these species and has been maintained to the present. In support of this hypothesis, the number of shared polymorphic sites was found to exceed the number found in simulations with independent accumulation of mutations. Strictly neutral evolution is exceedingly unlikely to maintain the polymorphism for such a long time. The allele multiplicity and extreme age of the alleles is consistent with Wright's classic one-locus population genetic model of gametophytic self-incompatibility. Similarities between the plant S locus and the mammalian major histocompatibility complex are discussed.

Original languageEnglish (US)
Pages (from-to)9732-9735
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number24
DOIs
StatePublished - Jan 1 1990

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Solanaceae
Prednisolone
Alleles
Genealogy and Heraldry
Genetic Drift
Genetic Models
Population Genetics
Major Histocompatibility Complex
Amino Acid Sequence
Genes

All Science Journal Classification (ASJC) codes

  • General

Cite this

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abstract = "Sequences of 11 alleles of the gametophytic self-incompatibility locus (S locus) from three species of the Solanaceae family have recently been determined. Pairwise comparisons of these alleles reveal two unexpected observations: (i) amino acid sequence similarity can be as low as 40{\%} within species and (ii) some interspecific similarities are higher than intraspecific similarities. The gene genealogy clearly illustrates this unusual pattern of relationships. The data suggest that some of the polymorphism at the S locus existed prior to the divergence of these species and has been maintained to the present. In support of this hypothesis, the number of shared polymorphic sites was found to exceed the number found in simulations with independent accumulation of mutations. Strictly neutral evolution is exceedingly unlikely to maintain the polymorphism for such a long time. The allele multiplicity and extreme age of the alleles is consistent with Wright's classic one-locus population genetic model of gametophytic self-incompatibility. Similarities between the plant S locus and the mammalian major histocompatibility complex are discussed.",
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Polymorphism at the self-incompatibility locus in Solanaceae predates speciation. / Ioerger, Thomas R.; Clark, Andrew G.; Kao, Teh-hui.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 87, No. 24, 01.01.1990, p. 9732-9735.

Research output: Contribution to journalArticle

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