A survey on the occurrence of papaya ringspot virus-P (PRSV-P) in Malaysia and genetic diversity assessment of the coat protein region

Papaya ringspot virus (PRSV) is a plant virus transmitted by aphids that has spread throughout many countries, including Malaysia, causing yield losses and economic impacts to the papaya industry worldwide. PRSV infection in papaya-distinctive ring-shaped patterns on papaya leaves resulted in stunted growth and reduced fruit quality. Management strategies such as the use of resistant varieties, cultural practices, and vector control are employed to mitigate the spread of PRSV. However, the evolution of new virus strains and the uncertainties posed by climate change pose ongoing challenges for the management of PRSV worldwide. Therefore, in this present study, we aim to confirm the presence of PRSV in symptomatic papaya leaves, to depict the current status of PRSV in Malaysia. Using reverse-transcription PCR (RT-PCR) targeting PRSV partial nuclear inclusion b protein (NIb) and coat protein (CP), 13 out of 40 papaya leaves collected were found positive for the PRSV strain-P (PRSV-P). Nucleotide analysis revealed a high similarity with strains from Taiwan and India, showing 96.83%, 97.03%, and 97.03% identity with the Taiwan strains (DQ340771, AY027810) and the India strain (KJ755852), respectively. Compared to the CP gene of Malaysian isolates reported in 2016 (EU082207), several nonsynonymous mutations have been discovered suggesting genetic diversity within the PRSV population in Malaysia. Overall, this study confirms the current circulation of PRSV infection in Malaysia since it was first identified in Johore in 1991. The re-occurrence of PRSV-P in this study highlights the need for continuous monitoring and targeted management strategies to prevent the further spread of PRSV-P in Malaysia.