MULTI-ALLELIC SELF-INCOMPATIBILITY POLYMORPHISMS IN PLANTS

The multi-allelic self-incompatibility polymorphisms in angiosperms ha ve long interested geneticists and population geneticists, but the lim its of classical genetic resolution were reached many years ago. In re cent years, new progress has been made by molecular genetic approaches . Intriguing similarities to and differences from the fungal systems a re emerging. The polymorphism at these loci is now known to be even mo re baroque than appeared from classical genetic studies. Alleles diffe r so much at the level of both the DNA and protein sequence that they would be difficult to recognise as products of the same locus, were it not for the presence of certain conserved regions. Despite the succes ses of the recent work, the locus responsible for the specificity of t he incompatibility reaction in pollen, and the mechanism of self-incom patibility, remain elusive.