Polymorphism at the self-incompatibility locus in Solanaceae predates speciation.
AUTOR(ES)
Ioerger, T R
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=55247Documentos Relacionados
- Gene and Allelic Genealogies at a Gametophytic Self-Incompatibility Locus
- Gametophytic Self-Incompatibility Systems.
- Excess nonsynonymous substitution of shared polymorphic sites among self-incompatibility alleles of Solanaceae.
- The Genetics of Self-Incompatibility in Oenothera Organensis
- The Deterministic Behavior of Self-Incompatibility Alleles