Abstract: Papaya ring spot virus(PRSV) and Papaya leaf-distortion mosaic virus(PLDMV) are dominant viruses causing papaya leaf mosaic disease in tropical and subtropical regions, threatening papaya planting industry. In this study, 27 suspected papaya leaf mosaic disease samples were collected and identified from Sanya, Ledong, Wanning and Qionghai in Hainan province. Total RNA from leaves was extracted and used for reverse transcription to obtain the corresponding cDNAs. Gene-specific primers were designed according to CP, P1, Hc-Pro and NIb gene nucleotide sequences from PRSV genome and CP gene nucleotide sequences from PLDMV genome. By PCR and sequencing, 20 PRSV-infected samples(74.1%), 3 PLDMV-infected samples(11.1%) and 1 PRSV-PLDMV cross-infected sample(3.7%) were identified. Phylogeny analysis showed that 3 PRSV varieties were existed in Hainan province with high strain differentiation, whereas, PLDMV varieties in Hainan province had a common origin with PLDMV varieties from Taiwan and Chian and Japan. The results showed that PRSV and PLDMV were dominant papaya mosaic viruses in Hainan, and the homology was below 95% during 3 PRSV varieties. This study would contribute to the subsequent construction of bivalent expression vector that could resist both PRSV and PLDMV viruses.

Key words: Papaya, PRSV, PLDMV