title: Molecular variation at the self-incompatibility locus in natural populations of the genera Antirrhinum and Misopates.
abstract: The self-incompatibility system of flowering plants is a classic example of extreme allelic polymorphism maintained by frequency-dependent selection. We used primers designed from three published Antirrhinum hispanicum S-allele sequences in PCR reactions with genomic DNA of plants sampled from natural populations of Antirrhinum and Misopates species. Not surprisingly, given the polymorphism of S-alleles, only a minority of individuals yielded PCR products of the expected size. These yielded 35 genomic sequences, of nine different sequence types of which eight are highly similar to the A. hispanicum S-allele sequences, and one to a very similar unpublished Antirrhinum S-like RNase sequence. The sequence types are well separated from the S-RNase sequences from Solanaceae and Rosaceae, and also from most known "S-like" RNase sequences (which encode proteins not involved in self-incompatibility). An association with incompatibility types has so far been established for only one of the putative S-alleles, but we describe evidence that the other sequences are also S-alleles. Variability in these sequences follows the pattern of conserved and hypervariable regions seen in other S-RNases, but no regions have higher replacement than silent diversity, unlike the results in some other species.
authors.affiliation: Institute of Cell Animal and Population Biology, University of Edinburgh, Ashworth Laboratories, King's Buildings, W. Mains Road, Edinburgh EH9 3JT, Scotland, UK.
authors.forename: C P
authors.initials: CP
authors.lastname: Vieira
authors.forename: Deborah
authors.initials: D
authors.lastname: Charlesworth
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D003433:Crosses, Genetic; D018076:DNA, Complementary / Q000378:metabolism; D014644:Genetic Variation; D007438:Introns; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012260:Ribonucleases / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D012260:Ribonucleases