Overexpression of Strictosidine Synthase Like-6 Gene in Arabidopsis thaliana

The monoterpenoids comprise a family of structurally and pharmaceutically diverse alkaloids. Strictosidine synthase is a key enzyme in monoterpenoid indole alkaloid biosynthesis pathway. In spite of the apparent lack of complex alkaloids in Arabidopsis, a gene family called Strictosidine synthase like (SSL) has been found in the genome. SSL6, a member of SSL family, has been induced significantly by various stresses and signaling molecules. An overexpressed mutant is a powerful tool for functional characterization of an unknown gene. In view of that, SSL6 overexpressed mutant have been generated in order to study the possible role of the gene in Arabidopsis defense against biotic and abiotic stresses. The open reading frame from SSL6 was amplified and cloned into intermediate pJET vector before subcloning into pPZPY122 plant vector. Plant transformation was made by floral dip method using Agrobacterium tumefaciens strain GV3101 (PMP90). The putative transgenic plants were isolated on selective MS medium containing gentamycin. Transgene integration was further analyzed by PCR using SSL6 and gentamycin resistance gene specific primers. The transcription level of SSL6 in the T2 plants was measured using q-PCR and indicated an overexpression in transgenic compared to wild type Col-0 plants. Segregation ratio of plants in T2 and T3 generation on selection medium proved that some of the genotypes contain single T-DNA insert. The SSL6 Expression level in response to salt stress was measured in Col-0 and indicated an up-regulation of the gene 3, 6 and 12 hrs after treatment.