Development of Pepper Transgenic Plants via Agrobacterium and Biolistic Transformation

Pepper (Capsicum annuum L.)is an economically important vegetable and spice crop. In our laboratory we have established a regeneration and transformation protocol for the sweet red pepper type 'Florinis' and for two pepper hybrids PO1 and C using hypocotyl explants. The rate of plant regeneration was found to depend on the types of explants cultured and the media used. In our regeneration protocol shoot bud initiation is more effective on MS media supplemented with IAA and BAP and shoot bud development is promoted with addition of GA3. Rooted shoots are successfully established in soil. In order to achieve the transformation of pepper we applied two different methods, using Agrobacterium and the particle gun. Following the first method fertile transgenic pepper plants were regenerated from hypocotyl explants that were co-cultivated with Agrobacterium tumefaciens strain LBA4404 harboring a plasmid that contains the gus reporter gene and the nptII selection gene or a plasmid with the Cu/Zn SOD gene of tomato, that is expressed in chloroplasts. Transgenic pepper plants were developed, verified and characterized but the percentage of transformed plants obtained using Agrobacterium is rather small and that is why we have applied as alternative the biolistics method. According to the method pepper hypocotyls as explants were bombarded by the hand gene gun of Bio-Rad. The plasmid that used in this transformation contains the gus reporter gene driven by the CaMV-35S promoter. The reporter gene facilitates the comparison of the two transformation methods, and indeed the number of the kanamycin-resistant plants that were produced through the particle gun seem to be quite large.