ISHS Acta Horticulturae 575: International Symposium on Tropical and Subtropical Fruits
PAPAYA RINGSPOT VIRUS RESISTANCE GENES AS A STIMULUS FOR DEVELOPING NEW CULTIVARS AND NEW PRODUCTION SYSTEMS |
| Authors: | M.M.M. Fitch, T. Leong, L. Akashi, A. Yeh, S. White, S. Ferreira, P. Moore |
| Keywords: | Papaya transformation, clonal propagation, backcross hybrids |
| Abstract:
Transgenic papaya ringspot virus (PRSV) resistant cultivars have revitalized a papaya industry that nearly collapsed following an outbreak of PRSV. Other crop production challenges remain, for example, the agronomic practice of direct multiple seeding for later thinning to a single hermaphrodite tree remains wasteful of seed, labor, and resources. In addition, Hawaii’s major papaya production region with rocky, shallow soil and high rainfall could expand to more highly productive deep, irrigated soils if cultivars selected for these environments were also resistant to PRSV. We developed clonal propagation systems to replace multiple seedlings. Growth and yield trials showed that the clonally propagated plants bore fruit earlier, lower on the trunk, and could be harvested without extra equipment for a longer period than could seedlings. We developed new PRSV resistant cultivars by direct genetic transformation and also introgressed the PRSV resistance gene from Rainbow F2 progeny into the soil-adapted, Phytophthora-tolerant cultivar Kamiya. The fruit of Kamiya is distinguished from that of Rainbow in that it is larger with a thick orange-yellow flesh and flavors reminiscent of coconut or mango. Both hybridization and transformation programs produced PRSV resistant lines of Kamiya. Rainbow F2 plants have also been backcrossed with their firm-fleshed Kapoho parent to improve shipping and handling qualities while maintaining resistance to PRSV and Phytophthora. Progeny from these crosses are performing well and may lead to the development of new cultivars. Results of evaluation trials will be given. | |
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