Miller and Venable (1) claimed that polyploidy is a “trigger of unrecognized importance” for the evolution of gender dimorphism, an idea originally proposed by Jennings (2) and Baker (3). In our opinion, their phylogenetic analysis of North American Lycium (Solanaceae) does not support the claimed associations between polyploidy, self-fertility, and gender dimorphism. There is no support (boots...

A growing number of T2/S-RNases are being discovered in plant genomes. Members of this protein family have a variety of known functions, but the vast majority are still uncharacterized. We present data and analyses of phylogenetic relationships among T2/S-RNases, and pay special attention to the group that contains the female component of the most widespread system of self-incompatibility in fl...

A method is proposed for characterizing the structure of genealogies among alleles that regulate self-incompatibility in flowering plants. Expected distributions of ratios of divergence times among alleles, scaled by functions of allele number, were generated by numerical simulation. These distributions appeared relatively insensitive to the particular parameter values assigned in the simulatio...

Chinese cabbage (Brassica rapa L. var. pekinensis) is an important vegetable in Asia, and most Japanese commercial cultivars of Chinese cabbage use an F1 hybrid seed production system. Self-incompatibility is successfully used for the production of F1 hybrid seeds in B. rapa vegetables to avoid contamination by non-hybrid seeds, and the strength of self-incompatibility is important for harvesti...

The self-incompatibility (S) genes of flowering plants are, with the fungal incompatibility and mammalian major histocompatibility (MHC) loci, among the most highly polymorphic loci known. In Oenothera organensis, for example, 35 alleles have been detected [1] by laborious compatibility tests between plants of this endemic species, the total population size of which may not exceed 5000 [2]. Dif...

Self-incompatibility in Brassica oleracea is controlled by the highly polymorphic S locus. Isolation and subsequent characterization of the S-locus-glycoprotein (SLG) gene, which encodes the S-locus-specific glycoprotein (SLSG), has revealed the presence of a self-incompatibility multigene family. One of these S-locus-related genes, SLR1, has been shown to be expressed. In this study we present...