In the Brassica genus, self-incompatibility (SI) is considered to be contro
lled by the combined action of several highly polymorphic genes located at
the S-Locus. These genes, including the S-Locus Gene (SLG), and the S-Recep
tor Kinase (SRK) are all members of the complex multigenic S-family. The S-
Locus Related I gene (SLR1) is a member of the S-family, but is not involve
d in SI control since it is not linked to the S-locus and is essentially mo
nomorphic. Here we confirm or demonstrate the occurrence of SLR1 as highly
diverged but not very polymorphic genes:in several genera of the Brassicace
ae family (Arabidopsis, Brassica, Hirschfeldia, Raphanus, Sinapis). They sh
ow similar expression patterns with respect to location (stigmatic papillae
), developmental stage (before and during anthesis) and transcript size (1.
6 kb). In addition, they are assumed to be involved in the same biological
function (late pollen adhesion). These features suggest that the pollen adh
esion function might have evolved towards self-pollen recognition through d
uplication of SLR1 and recruitment of a protein kinase gene.