Papaya ring spot virus: Status of 80 years of global research

Commercialized genetically modified (GM) papaya cultivars have protected papaya from the devastating disease caused by papaya ringspot virus (PRSV). However, papaya leaf distortion mosaic virus (PLDMV), which causes similar infection symptoms but is serologically distinct from PRSV, was found to be a competitive threat to the papaya industry. Our study surveyed the occurrence of PRSV and PLDMV, as well as the transgenic markers of the 35S promoter from cauliflower mosaic virus and the neomycin phosphotransferase II gene in feral papaya plants, which were found frequently growing outside of cultivated papaya fields on Hainan Island. In total, 123 feral papayas, comprising 62 (50.4%) GM plants and 61 (49.6%) non-GM ones, were sampled. Among them, 23 (18.7%) were positive for PRSV, 49 (39.8%) were positive for PLDMV (including five plants co-infected by PRSV and PLDMV), and 56 (45.5%) were free of either virus. In traditional papaya-growing regions, we detected fewer PRSV-infected plants (2 in 33, 6%) than in other regions (21 in 90, 23%). However, overall, whether plants were transgenic or not made no difference to PRSV incidence ( P = 0.230), with 9 PRSV-infected plants among 62 GM papayas and 14 among 61 non-GM papayas. Phylogenetic and genetic differentiation analysis showed a clear correlation between PRSV and PLDMV populations and their geographic origins. Negative selection was estimated for the selected gene regions of both viruses. Notably, PLDMV has deviated from neutral evolution and experienced population expansion, exhibiting increased genetic diversity, and is becoming the predominant threat to papaya in Hainan.

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Epidemiological studies on the incidence of papaya ringspot disease under Indian sub-continent conditions

Mesta,

Basavarajappa

et al. 2024

Preprint

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Papaya (Carica papaya L.) is a commercially important fruit crop cultivated worldwide due to its nutritional and medicinal values. Papaya ringspot disease (PRSD), caused by the papaya ringspot virus (PRSV), poses a significant threat to papaya cultivation, resulting in substantial yield losses. In this study, two independent field experiments were conducted at Bagalkote located in the Northern Dry Zone of Karnataka. The first experiment aimed to determine the optimal planting month for papaya to effectively manage PRSV disease. The second experiment aimed to determine the susceptibility stage of papaya to PRSV infection. The results revealed that planting papaya in March was identified as the best month for planting, as it exhibited the lowest disease incidence along with superior growth and yield characteristics compared to other planting months. On the other hand, planting during the winter season (September to January) resulted in high disease severity due to an increased aphid population. Conversely, planting during the low aphid population period (spring season) delayed disease incidence until the monsoon. By the time the aphid population starts to increase, the plants have already passed the flowering and fruit-bearing stages. In the second experiment, the severity and frequency of foliar symptoms on PRSV-inoculated papaya plants were significantly higher in plants inoculated at the early growth stage compared to those inoculated at a later growth stage. This suggests that the early crop growth stage (up to 180 days after transplanting) is a critical period for PRSV infection, and effective disease management measures should be implemented during this time to control the spread of the disease and improve growth and yield parameters. Additionally, plants inoculated at an early stage had a higher viral titer, more severe symptoms, and a higher percent transmission rate compared to those inoculated at a later stage, demonstrating a highly significant and positive correlation using qRT-PCR.

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Papaya ring spot virus: Status of 80 years of global research

Cited by 3 publications

References 139 publications

Molecular approaches for the management of papaya ringspot virus infecting papaya: a comprehensive review

Molecular approaches for the management of papaya ringspot virus infecting papaya: a comprehensive review

Genetic Variability and Evolutionary Dynamics of Papaya Ringspot Virus and Papaya Leaf Distortion Mosaic Virus Infecting Feral Papaya in Hainan Island

Epidemiological studies on the incidence of papaya ringspot disease under Indian sub-continent conditions

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