Tennant, P. F.; Pinnock, S. E.; Powell, M.; Wheatley, A. O.; Minott, D. A.
Author Affiliation, Ana.
An overview of the safety assessment of transgenic papaya for the management of Papaya ringspot virus in Jamaica.
Transgenic Plant Journal
Date of Publication
Papaya (Carica papaya L.) production in Jamaica suffered severe losses due to the type p Papaya ringspot virus (PRSV), causing devastation to over 40% of local papaya orchards in the past 15 years. Absence of genetic resistance in commercial cultivars has directed disease management efforts towards examination of transgenic resistance. Recently a number of transgenic lines were engineered with the coat protein gene (cpT) of a Jamaican PRSV strain via microprojectile bombardment. Under field tests, R1 transformants exhibited virus-resistant (70-75%) phenotypes. Trees were monoecious, producing red-flesh fruits similar in weight to the non-transgenic controls although some yellow-flesh fruits were obtained from two lines. Nutritional (e.g. vitamins, sugars) and anti-nutritional components (benzyl isothiocyanate, oxalate and cyanide) were assessed. With the exception of one cpT transgenic line, no significant differences to the control were observed in the levels of nutrients and anti-nutrients at various stages of maturity, although a few random variations were noted. A sub-chronic feeding study in rats revealed markers of general health, body weight, food intake, and activities of plasma, liver and kidney function enzymes, to be comparable for animals fed diets of cpT transgenic papaya and those of the control group. No effects were observed with the liver or kidney, in organ weights or histopathology. Although not statistically relevant, variations were recorded in some parameters. Thus, the cpT transgenic papaya lines possess nutritional attributes and resistance to PRSV that can be manipulated in subsequent generations for development of products with acceptable commercial performance. Factors affecting the deregulation and commercialization of the transgenic product are discussed.....