Molecular variation at the self-incompatibility locus in natural populations of the genera Antirrhinum and Misopates

• Published in: Heredity 2002-03, Vol.88 (3), p.172-181
• Main Authors: Vieira, C P, Charlesworth, D
• Format: Article
• Language: English
• Subjects: Alleles; Amino Acid Sequence; Antirrhinum hispanicum; Biomedical and Life Sciences; Biomedicine; Crosses, Genetic; Cytogenetics; Deoxyribonucleic acid; DNA; DNA, Complementary - metabolism; Ecology; Evolutionary Biology; Flowering plants; Genetic Variation; Genomics; Human Genetics; Introns; Misopates; Models, Genetic; Molecular Sequence Data; Natural populations; original-article; Phylogeny; Plant Genetics and Genomics; Plant Proteins - metabolism; Plants - genetics; Polymerase Chain Reaction; Polymorphism, Genetic; ribonuclease; Ribonucleases - metabolism; S gene; Sequence Analysis, DNA; Sequence Homology, Amino Acid
• ISSN: 0018-067X; 1365-2540
• DOI: 10.1038/sj.hdy.6800024

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sequence types of which eight are highly similar to the A. hispanicum S -allele sequences, and one to a very similar unpublished Antirrhinum S -like RNase sequence.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.