XVI International Botanical Congess

One of the major goals in self-incompatibility (SI) research is identification of the pollen S-gene whose allelic products interact with the products of the pistil S-RNase gene to elicit SI responses. The pollen S-gene must fulfill two criteria: (1) it must be physically linked to the S-RNase gene of the same S-haplotype, and (2) there must be sufficient sequence polymorphism between pollen S-alleles to encode a unique allelic specificity. Through the use of differential display and subtractive hybridization, we have isolated 14 distinct pollen-expressed genes of P inflata that all lie within a centimorgan of the S-RNase gene. The characteristics of these genes will be discussed. We are using these genes as molecular markers in undertaking a 'functional genomic' approach to characterize the S-locus and search for the pollen S-gene, in case none of these 14 genes is the pollen S-gene.