XVI International Botanical Congess

Self-incompatibility in solanaceous plants is controlled by a single, multiallelic S locus. Pistils of self-incompatible plants reject pollen ifboth pistil and pollen have the same S allele. No rejection occurs if the S alleles are different. This indicates that pollen and pistil exchange signals encoded by the S locus. A ribonuclease in the pistil called the S-RNase determines the pistil's self-incompatibility phenotype but does not determine the phenotype of pollen. This is presumably encoded by a separate gene at the S locus. Identifying the pollen-S gene is a major goal of self-incompatibility research. In this talk, I will discuss how mutants have helped us understand the molecular basis of self-incompatibility in solanaceous plants and report on recent progress towards identifying the pollen-S gene.