Differential Gene expression analysis to study sporophytic self-incompatibility in hazel

The European hazelnut (Corylus avellana L.) is a monoeciuos tree and exhibits sporophytic self-incompatibility. Self-incompatibility is a genetic system, controlled by a single multi-allelic locus (the S locus), that prevents the self-fertilization and allows the pistil to throw back the pollen of genetically close individuals. The involved molecular mechanisms are partly known only in the Brassicaceae, but the sporophytic self-incompatibility (SSI) has been detected also in Asteraceae, Betulaceae, Caryophillaceae, Convolvulaceae and Sterculiaceae. Studies on gene regulation of fertility, pollination and fertilization in hazelnut are very few; with this research we propose to contribute to the knowledge about the mechanism of sporophytic self-incompatibility in hazelnut. In a first stage, homologies with known sequences of Brassicaceae were sought using degenerated primers but without success. Therefore, the Differential Display technique was applied for the study of the female determinant of self-incompatibility. Two developmental stages of female flower buds were compared: before styles emergence and full bloom. Partial sequences that showed an interesting homology degree with transmembrane serine-threonine kinase receptor of Brassica oleracea were isolated. Believing that the female determinant of self-incompatibility in hazelnut is very likely a membrane receptor, primers were designed on conserved regions of serine-threonine kinase receptors. Four differentially expressed fragments were isolated from stigmas at full bloom: after blasting in TIGR and NCBI databases, 1 was homologous with a gene for a kinase receptor, 3 were homologous to kinase proteins. The isolated sequences are being studied to check their expression in different plant tissues and developmental stages stigmas.