ISHS Acta Horticulturae 370: International Symposium on Tropical Fruits
PAPAYA BREEDING FOR PRV RESISTANCE |
| Authors: | R. Manshardt, S. Lius, S. Sondur, T. Wenslaff, M. Fitch, J. Sanford, F. Zee, D. Gonsalves, J. Stiles, S. Ferreira, J.L. Slightom |
| Abstract:
Moderate genetic resistance to PRV in papaya germplasm has been used inconventional breeding programs in Florida and Hawaii USA to create PRV-tolerant cultivars that are a compromise between useful resistance and acceptable fruit quality. In Hawaii, phenotypic recurrent selection and RAPD marker assisted selection are being employed to improve fruit quality and PRV resistance in populations derived from crossing a virus-tolerant parent with commercial cultivars. Cross-protection has been demonstrated to interact positively with genetic resistance to PRV to enhance the level of virus protection. Excellent resistance to PRV has been reported in several wild Carica species, and interspecific hybrids have been obtained through embryo rescue in Venezuela, India, the USA, and Taiwan. In Hawaii, several Fl interspecific hybrids were vigorous and showed good field resistance to PRV. However, Fl's were quite sterile, and backcrossing has produced only infertile sesquidiploids from unreduced megaspores. In the USA, genetically engineered papaya plants have exhibited coat protein-mediated PRV resistance, ranging in different clones from a slight delay in the onset of symptoms to apparent immunity. Resistant plants transmit the resistance gene to their progenies as a simple Mendelian factor, demonstrating stable chromosomal incorporation of the gene construct. In a field trial in Hawaii, one transgenic clone has remained free of PRV symptoms and ELISA negative for 16 months following manual or aphid-vectored inoculation with the virus. | |
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