Effect of plating density, amino acid and osmoticum on transformation efficiency of papaya (Carica papaya L.)

Papaya suffers colossal losses due to Papaya Ring Spot Virus (PRSV) disease. PRSV is responsible for about 70% loss in papaya production worldwide. This disease is present all over the world wherever papaya is grown. Transgenic papaya varieties namely SunUp and Rainbow have been developed and commercialized in the USA using Pathogen Derived Resistance (PDR). The present investigation reports a successful gene delivery system in an Indian papaya variety employing PDR. Agro-infected immature young globular embryos of papaya cv. Pusa Delicious were co-cultivated with A. tumefaciens harboring a hairpin loop construct of a truncated PRSV coat protein gene. The Agro-infected explants were plated at a density of 2–3, in the presence of 100 mg L⁻¹ L-cysteine in dark for 72 h. Transformed plants maturation under the influence of 45 mg L⁻¹ PEG produced 4 independent transgenic events which were characterized by PCR and data sequencing.