ANALYSIS OF EXPRESSED PROTEINS IN THE POLLEN TUBE OCCURRING SELF-INCOMPATIBLE RESPONSE USING MASS OR SINGLE-CULTURE SYSTEM OF MATURE POLLEN IN CITRUS

To analyze the protein expression of pollen grains and tubes having self-incompatible reactions in Hyuganatsu (Citrus tamurana Hort. ex Tanaka), we cultured mature pollen and treated it with crude extracts from the styles using a mass or single liquid culture system, and we collected pollen grains and tubes for proteome analysis. The relative expression of each identified protein was quantified by an imager and revealed as a value relative to the pollen grain. Eleven identified proteins were remarkably up-regulated (above 1.2-fold) or down-regulated (under 0.8-fold) in treatment with self-incompatible reactions. Eight of these proteins were predicted to be self-incompatible-related proteins with the reported functions. In this study, F-box protein was identified as showing minimum expression in the treatment with crude extracts from styles of Hyuganatsu (self-incompatible reactions). The S-locus gene product expressed in pollen has been identified as an F-box protein in Solanaceae and Rosaceae. It is not clear whether a mechanism similar to that of Solanaceae and Rosaceae exists in the self-incompatible reaction in Hyuganatsu; however, the reduced expression of F-box protein may induce a self-incompatible reaction.