Molecular population genetics of the SRK and SCR self-incompatibility genes in the wild plant species Brassica cretica (Brassicaceae).
Self-incompatibility (SI) in plants is a classic example of a trait evolving under strong frequency-dependent selection. As a consequence, population genetic theory predicts that the S locus, which controls SI, should maintain numerous alleles, display a high level of nucleotide diversity, and, in structured populations, show a lower level of among-population differentiation compared to neutral loci. Population-level investigations of DNA sequence variation at the S locus have recently been carried out in the genus Arabidopsis, largely confirming results from theoretical models of S-locus evolutionary dynamics, but no comparable studies have been done in wild Brassica species. In this study, we sequenced parts of the S-locus genes SRK and SCR, two tightly linked genes that are directly involved in the determination of SI specificity in samples from four natural populations of the wild species Brassica cretica. The amount and distribution of nucleotide diversity, as well as the frequency spectrum of putative functional haplotypes, observed at the S locus in B. cretica fit very well with expectations from theoretical models, providing strong evidence for frequency-dependent selection acting on the S locus in a wild Brassica species.
Edh
Kristina
K
Department of Cell and Organism Biology, Lund University, Lund, Sweden.
Widén
Björn
B
Ceplitis
Alf
A
D001937:Brassica / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D014644:Genetic Variation; D006239:Haplotypes; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics*; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
D018744:DNA, Plant; D010940:Plant Proteins; C431526:SP11 protein, Brassica; D011494:Protein Kinases; C079832:S-receptor kinase