Asian Journal of Research and Review in Agriculture

Papaya (Carica papaya L.), in family; caricaceae is an important fruit crop all over the world. Papaya Ring Spot Virus (PRSV) causes one of the most destructive diseases of papaya, lowering its yield. Genetic engineering has been proven to be a useful tool to introduce genes to plants where conventional breeding methods have failed. Most of the successful plant genetic engineering applications are involved with transforming of genes using Agrobacterium mediated transformation where regeneration of plants using tissue culture-based techniques.   Hence, the present study was conducted to develop tissue culture-based C. papaya through somatic embryogenesis from zygotic embryos of papaya for subsequent genetic engineering to obtain PRSV resistance. Immature fruits were randomly selected from self-pollinated plants in the field.  Zygotic embryos were directly excised from sterilized seeds and successfully initiated on half strength Murashige and skoog (MS) medium. The medium supplemented with 400 mg/L glutamine and different concentrations of 2, 4 Di- chlorophenoxyaciatic acid (2,4-D) (3 ml/L to 12 ml/L) and different amounts of vitamins (5 ml/L to 10 ml/L) were tested as calli induction medium. The medium supplemented with 10 mg/L 2,4-D and 5 ml/L vitamin consisted of significantly higher number of calli (60%). The inducted pre-embryogenic calli were matured on hormone free medium. The matured somatic embryos were introduced into the germination medium containing full strength MS salts supplemented with different concentrations of kinetin (1 ml/L to 6 ml/L). The medium supplemented with 2 mg/L of kinetin recorded the significantly highest number (75%) of plants compared to the other media within the stipulated time duration. Germinated embryos were introduced into full strength MS media without hormones. The fully grown plants with high density root system were acclimatized gradually for a period of three months.