Tissue culture and transformation were the most difficult task for developing the transgenic papaya [54]. However, this mission was taken into consideration by Fitch and Manshardt [55], three different cultivars (Sunset,
Sunrise Kapoho) were targeted. To develop a papaya regeneration system through organogenesis, a great effort
has been made by Fitch but unfortunately he was unsuccessful. Soon after, a quick decision has been made to
use embryogenic tissue transformation through particle bombardments. Therefore, with tungsten particles coated
with DNA of the PRSV HA 5-1 coat protein gene with the gene gun, embryogenic tissue was bombarded [56].
Then after 15 months in the greenhouse, transgenic plants were obtained and growing in the good conditions [57].
However, genetic engineering through particle bombardment and Agrobacterium-mediate both create relatively random integration of the transgene into the host genome [58]. In addition, the expression of the transgenes considerably affected by the random integration and similarly gene disruption could possibly occur due to
this integration [58]. Southern blot hybridization, however, is useful mechanism for evaluating transgene copy
number of insertion but the physical location of the transgene insertion cannot be indicated [58].