2018 ASHS Annual Conference

Most rosaceous fruit tree species, such as plum, cherry, apple, and etc, show self-incompatibility (SI). SI hinders efficient breeding and cultivation in these fruit tree species. Three plant families Rosaceae, Solanaceae and Plantaginaceae share the common SI system called the S-RNase-based gametophytic SI, which uses S-RNase and F-box protein as the specificity determinants in pistil and pollen, respectively. Although similar molecules are involved in specificity determination in SI recognition reaction across different taxa, accumulated data suggests the presence of distinct SI recognition mechanisms. While the pistil S determinant S-RNase is considered to have a cytotoxic effect against pollen tube RNA in the Rosaceae, Solanaceae and Plantaginaceae, the pollen S determinant F-box proteins are suggested to have different functions in genus Prunus and in the other taxa that show the S-RNase based SI. Pollen S in Prunus is assumed to release cytotoxicity of self S-RNase, while in the other taxa, pollen S is considered to be involved in S-RNase detoxification. Since the genome sequence information from various plant taxa has been available, we are now able to utilize new approaches such as evolutionary analysis and genome re-sequencing to uncover molecular mechanism of SI. Here, we summarize recent advances in our understanding of SI mechanism in Prunus based on the genome-wide analyses.