Development of Transgenic Papaya throughAgrobacterium-Mediated Transformation

Abstract

Transgenic papaya plants were regenerated from hypocotyls and immature zygotic embryo after cocultivation withAgrobacterium tumefaciensLBA-4404 carrying a binary plasmid vector system containing neomycin phosphotransferase (nptII) gene as the selectable marker andβ-glucuronidase (GUS) as the reporter gene. The explants were co-cultivated withAgrobacterium tumefacienson regeneration medium containing 500 mg/L carbenicillin + 200 mg/L cefotaxime for one week. The cocultivated explants were transferred into the final selection medium containing 500 mg/L carbenicillin + 200 mg/L cefotaxime + 50 mg/L kanamycin for callus induction as well as plant regeneration. The callus derived from the hypocotyls ofCarica papayacv. Shahi showed the highest positive GUS activities compared toCarica papayacv. Ranchi. The transformed callus grew vigorously and formed embryos followed by transgenic plantlets successfully. The result of this study showed that the hypocotyls ofC. papayacv. Shahi andC. papayacv. Ranchi are better explants for genetic transformation compared to immature embryos. The transformedC. papayacv. Shahi also showed the maximum number of plant regeneration compared to that ofC. papayacv. Ranchi.