Structural Characterization and Functional Analysis via Chimeric Genes of the Arabidopsis lyrata SRK36 and SCR36 Genes

Orthologs are genes in different species that originated through descent from a single gene of a common ancestor. This relationship remains true for several of the S-locus Receptor Kinase (SRK) and S-locus Cysteine Rich (SCR) genes between the angiosperm plant species Arabidopsis lyrata and Arabidopsis thaliana. These genes are highly polymorphic, and play a vital role in self-recognition necessary for the self-incompatibility (SI) trait. The primary goal of this honors project was to establish an orthologous relationship between the SRK36 and SCR36 genes of A. lyrata to the SRKC and SCRC genes of A. thaliana, respectively, and show that they are two haplotypes that originated from a single haplotype in a mutual predecessor. In order to establish this relationship, AlSRK36 and AlSCR36 genes were isolated, nucleotide sequenced, and used to generate chimeric genes in pNBSWBa and pNBSWSCRa Ti vectors, respectively. These constructs were then transformed into Agrobactria and A. thaliana plants, whereupon pollination assays were used to confirm their SI functionality. In pollination assays with transgenic plants containing the AtSRKC and AtSCRC chimeric genes (Honors Thesis, Molly Hritzo), the SI phenotype demonstrated by AlSRK36::AlSRKb flowers crossed with AtSCRC pollen firmly established the orthologous relationship between the A. lyrata S36 and A. thaliana SC plants.