PAPAYA RINGSPOT VIRUS IN AUSTRALIA AND THE DEVELOPMENT OF VIRUS RESISTANT PLANTS

Abstract

Papaya is a popular fruit crop in many tropical and subtropical regions. It grows quickly and is capable of bearing large crops. Because of extensive monoculture and a narrow gene-pool, papaya plants are susceptible to numerous diseases. Papaya ringspot virus, type P (PRSV-P), causes the most widespread of these diseases. Although it is not currently a major problem in Australia, PRSV-P dramatically reduces yield in many countries. Vasconcellea quercifolia is one of four wild Carica species that are known to be PRSV-P resistant. Hybrids of these species grow vigorously in the field. Males, females and hermaphrodites have been identified, and a few male hybrids exhibited some pollen fertility. A backcross generation has been produced. One plant was fertile and showed resistance to PRSV-P. Transgenic plants containing viral coat protein constructs have also shown resistance to PRSV-P in field plantings. In this paper, progress toward achieving PRSV-P resistance for papaya using both approaches is examined.