1. Self-incompatibility can limit the availability of compatible mates in small and isolated populations, eventually reducing average seed set to the point that the long-term persistence of the populations can be impaired. This phenomenon, named the S-Allee effect, is caused by the loss of alleles (S-alleles) at the self-incompatibility locus (S-locus) due to the intense genetic drift experienced by small populations. Quantifying the diversity of S-alleles is therefore of direct interest for biological conservation, but efficient genotyping methods have been lacking so far because of technical challenges associated with the typically extreme levels of polymorphism and complex genomic structure of the S-locus. 2. We used two alternative approaches to genotype the S-locus using NGS sequencing technologies in four natural populations of the endangered Brassica insularis in Corsica. First, we used an NGS amplicon-sequencing approach using generalist primers for each of the two classes of Brassica S-alleles. Second, we obtained whole genome shotgun short-read resequencing data and analyzed them with a recently developed bioinformatic pipeline dedicated to hypervariable loci, which we successfully validated on a public dataset comprising 119 cultivated accessions of B. oleracea. 3. By combining the two approaches in natural populations of B. insularis we identified 31 distinct S-alleles and obtained fully resolved S-locus genotypes for 319 out of 326 sampled individuals. The number of S-alleles varied from four in the smallest population to 18 in the largest one. As a result, the smallest population exhibited very low proportions of compatible individuals, potentially threatening its persistence. We conclude that introducing individuals carrying S-alleles currently absent from the population could help rescue fertility.
Maurice, S., Flaven, E., Genete, M., Blassiau, C., Mignot, A., Petit, C., Castric, V., Vekemans, X.
Advertisement
Stats
- Recommendations n/a n/a positive of 0 vote(s)
- Views 1
- Comments 0