Virus Coat Protein Transgenic Papaya Provides Practical Control of Papaya ringspot virus in Hawaii

Abstract

Since 1992, Papaya ringspot virus (PRSV) destroyed nearly all of the papaya hectarage in the Puna district of Hawaii, where 95% of Hawaii's papayas are grown. Two field trials to evaluate transgenic resistance (TR) were established in Puna in October 1995. One trial included the following: SunUp, a newly named homozygous transformant of Sunset; Rainbow, a hybrid of SunUp, the nontransgenic Kapoho cultivar widely grown in Puna, and 63-1, another segregating transgenic line of Sunset. The second trial was a 0.4-ha block of Rainbow, simulating a near-commercial planting. Both trials were installed within a matrix of Sunrise, a PRSV-susceptible sibling line of Sunset. The matrix served to contain and trace pollen flow from TR plants, and as a secondary inoculum source. Virus infection was first observed 3.5 months after planting. At a year, 100% of the non-TR control and 91% of the matrix plants were infected, while PRSV infection was not observed on any of the TR plants. Fruit production data of SunUp and Rainbow show that yields were at least three times higher than the industry average, while maintaining percent soluble solids above the minimum of 11% required for commercial fruit. These data suggest that transgenic SunUp and Rainbow, homozygous and hemizygous for the coat protein transgene, respectively, offer a good solution to the PRSV problem in Hawaii.

The Wayward Hawaiian Boy Returns Home

“…I was upset at those statements and when I gave my talk I told them that indeed everyone would be able to see whether the transgenic papaya would be resistant because Steve Ferreira had started a field trial in Puna. As noted above, the results from the field trial were beautiful, and the consensus was that we had an excellent transgenic papaya that was resistant to PRSV (9). In retrospect, however, the behavior of the few farmers was understandable because they were seeing their papaya crops melt under the attack of PRSV.…”

Genetic Engineering and Sustainable Crop Disease Management: Opportunities for Case-by-Case Decision-Making

“…This gene elicits RNAi against this highly destructive virus [21,80]. Such a GE application mimics cross-protection, a phenomenon in which symptoms due to severe strains of a virus can be reduced by prior infection by a mild strain.…”

“…However, when conventional breeding and other management options are inadequate, or when linkage drag limits the usefulness of conventionally derived traits, GE offers alternatives. As examples of diseases for which GE presently appears to represent the only acceptable disease management in culturally or economically important crops, consider papaya ring spot in Hawaii [21], cassava brown streak disease in Africa [22], and citrus greening in Florida [23][24][25]. The loss of important crops to infectious diseases is completely contrary to the principles of sustainability.…”

Identification, Mapping and Pyramiding of Genes/Quantitative Trait Loci (QTLs) for Durable Resistance of Crops to Biotic Stresses

“…It has been reported that single gene transformation results in insufficient or narrow spectrum disease resistance [27], and hence a genetic transformation of crop plants with a combination of resistance genes would be more logical [1]. So far, a number of transgenic crops with durable resistance to bacterial diseases [28,29], viral diseases [30][31][32], fungal diseases [33], insect pests [34,35] and herbicides [36,37] have been developed. Thus, it is possible to deduce that genetic engineering is also another useful tool to pyramid novel resistance genes into crop plants to develop durable resistance to biotic stresses [2].…”