Abstract
Most flowering plants have evolved self-incompatibility (SI) system to prevent inbreeding. In Brassica, SI is controlled by the S-locus, which encodes pollen and pistil determinants named SP11 (S locus protein 11) and SRK (S receptor kinase), respectively. The binding of SP11 to SRK induces the autophosphorylation of SRK to initiate the signaling cascades resulting in the rejection of self-pollen. MLPK (M-locus protein kinase), a cytoplasmic protein kinase, was shown to be involved in SI signaling, probably by forming a receptor complex with SRK. However, the direct target of MLPK and its exact role in SI signaling remain unclear.
To search for new interacting partners for MLPK, we performed Split-Ubiquitin Membrane Yeast Two-Hybrid screening, which enabled us to detect protein-protein interaction on plasma membrane. As a result, we identified several candidates for MLPK interactor. Some of these factors are involved in membrane trafficking, suggesting that membrane trafficking might be associated with SI reaction. Now, we are verifying their interactions by BiFC assay.
