Effect of papaya ringspot virus infection in Brazilian Carica papaya accessions under controlled conditions

Papaya ringspot virus strain P (PRSV-P) is the causative agent of one of the most devastating viral diseases affecting papaya cultivation regions. Although high resistance in papaya has not been reported, global papaya germplasm exhibits considerable diversity, leading to the identification of tolerant genotypes. In the present study, we assessed the resistance levels of 43 papaya accessions to PRSV-P. Disease evaluations were conducted by mechanically inoculating two-month-old papaya seedlings with a PRSV-P isolate and subsequently scoring them on a disease grading scale ranging from 0 to 5. The incubation period (IP) demonstrated a strong negative correlation of -0.82 with the disease index (DI) and -0.77 with the area under the disease progress curve (AUDPC). The DI and AUDPC displayed a perfect correlation of 0.99. Based on the DI values, the evaluated accessions were categorized as moderately susceptible or susceptible. The 'Cariflora' accession, previously reported as PRSV-P tolerant, exhibited the lowest DI at 37.33%, whereas S & atilde;o Mateus displayed the highest disease index at 62.67%. Although no accession was classified as moderately resistant or resistant, we will continue to assess papaya accessions for their resistance to PRSV-P infection, with the addition of more genotypes to the UENF/CALIMAN germplasm bank, especially adding dioecious genotypes.