Abstract
Many flowering plants have evolved self-incompatibility systems to prevent inbreeding. In Brassica, self/non-self recognition is controlled by the multiallelic gene complex (S-haplotypes) at the S-locus, which contains both determinants of the male (SP11: S-locus protein 11) and the female (SRK: S-receptor kinase). SP11 has been shown to activate its cognate SRK to trigger the signaling cascade that results in the rejection of self-pollen. However, the components working in this signaling cascade is still entirely unknown.
In this study, we searched for the stigmatic proteins that were phosphorylated after pollination by using in vivo 32P-labelling system followed by 2D-PAGE analysis. We found one protein that was specifically phosphorylated after self-pollination, and two that were specifically phosphorylated after cross-pollination. The former was shown to be phosphorylated within 30 min after self-pollination.
