Genetic mapping and protein product diversity of the self-incompatibility locus in wild tomato (Lycopersicon peruvianum).

Phenotypic diversity of self-incompatibility (S) alleles within nine natural populations of Lycopersicon peruvianum was investigated. Only 7 incompatible responses were observed of a total of 276 unique combinations tested, on the basis of controlled pollinations, indicating the large number of alleles that exist within these populations. Molecular weight polymorphism for specific major stylar proteins observed on SDS-PAGE was also evident in two of the populations examined. Five proteins were shown to map to the S locus and to be associated with different S alleles through controlled pollinations and segregation of the proteins. Two of these S related proteins had been described previously in terms of spatial and temporal expression consistent with their involvement in self-incompatibility (Mau et al., Planta 169, 184-191, 1986). A mapping population derived from a fully compatible cross was used to establish linkage of the S locus to two DNA markers, CD15 and TG184, that lie on chromosome 1. The order of the markers and estimates of map distances are given.