Screening Carica papaya × C. cauliflora hybrids for resistance to papaya ringspot virus‐type P

Abstract

Carica papaya, C. cauliflora and interspecific hybrids of these species were screened for resistance to two Australian isolates (338, 445) of papaya ringspot virus‐type P (PRSV‐P). Plants were manually inoculated with PRSV‐P in the glasshouse and the reaction assessed 30 days later by back‐inoculation to susceptible Cucurbita pepo and by a plate‐trapped antigen‐enzyme linked immunosorbent assay (PTA‐ELISA). Both parents and interspecific hybrids were also planted adjacent to infected C. papaya and 30 days later tested for PRSV‐P by PTA‐ELISA. All interspecific hybrid and C. cauliflora plants manually inoculated in the glasshouse or planted in the field failed to become infected, whereas C. papaya plants, in both situations, were infected by PRSV‐P. In addition, the surviving interspecific hybrid and C. cauliflora plants tested negative, while all C. papaya plants were positive for PRSV‐P in both the back‐inoculation and PTA‐ELISA tests. Thus, the interspecific hybrid and C. cauliflora plants were resistant to the Australian PRSV‐P isolates.