Constitution of the RV collection of mutants. A/Schematic representation of het-e and het-r alleles at the hnwd loci under study in the het-R het-V and the het-C het-E self incompatible strains. Plain arrowheads indicate non allelic incompatible interactions. B/Genesis and selection of new alleles at hnwd loci. During vegetative growth, the WD40 repeat instability promotes the rapid genesis of allelic variants at the hnwd loci for selection to act on. Our experimental set up selects for loss of function mutations while in natural conditions in the wild, selection will promote the maintenance of new recognition specificities. C/Selection of loss of function mutants in our experimental set up. Basically, SI strains were grown for 24 h in permissive condition before incubation for five days in non permissive conditions. Arrows indicate mutant sectors escaping from cell death from a single culture, as opposed to a culture where no mutant sector appeared. A single mutant per subculture was picked up for further analysis.