Efficient genetic transformation of papaya using RNAi CP gene against papaya ringspot virus

Abstract

Papaya Ring Spot Virus disease is wide spread across papaya growing countries of the world and is one of the major impediments in successful papaya cultivation. Genetically engineered papaya varieties viz., SunUp and Rainbow have already been developed and commercialized in USA using coat protein mediated resistance. However, transgenic papaya conferring resistance to papaya ringspot virus has not been developed in India till date due to lack of suitable genetic transformation protocol for Indian papaya varieties and unavailability of coat protein gene construct for harbouring broad-spectrum resistance. The current study reports an efficient gene delivery mechanism in papaya. Young globular embryos infected for 30 minutes with Agrobacterium tumefaciens strain LBA 4404 harbouring hairpin loop of truncated coat protein gene and subsequently co-cultivated in presence of 100 pM acetosyringone and 1mM spermidine in dark for 72 hours gave rise to independent transgenic events characterized by PCR, dot blot hybridisation and RT-PCR.