New Virus Found in Papayas: Genome Sequence and Family Tree Analysis

Jim Crocker
21st June, 2024

New Virus Found in Papayas: Genome Sequence and Family Tree Analysis

Image Source: Natural Science News, 2024

Key Findings

  • Researchers in Ecuador discovered a new virus, named "papaya sticky fruit-associated virus" (PSFaV), affecting papaya crops
  • PSFaV is genetically similar to other known viruses, suggesting it shares a recent evolutionary ancestor with them
  • Understanding PSFaV's genetic makeup helps develop tools for early detection and management of papaya sticky disease (PSD)
Papaya, a tropical fruit beloved for its rich flavor and nutritional benefits, faces significant agricultural challenges due to viral infections. One such challenge is papaya sticky disease (PSD), which can cause severe crop losses. Recent research from the Escuela Superior Politécnica del Litoral has identified a new virus, provisionally named "papaya sticky fruit-associated virus" (PSFaV), which adds to our understanding of the complex viral landscape affecting papaya crops[1]. PSFaV is a double-stranded RNA (dsRNA) virus with a genome length of 9,199 nucleotides. It contains two discontinuous open reading frames (ORFs), which are segments of the genome that can be translated into proteins. The virus shows a high degree of genetic similarity to babaco meleira-like virus (BabMelV), with 79.4% and 83.3% identity at the nucleotide and amino acid levels, respectively. BabMelV is an uncharacterized virus found in babaco, a fruit related to papaya, in Ecuador. This genetic similarity suggests that PSFaV and BabMelV share a recent evolutionary ancestor. The study also found that PSFaV has about 50% sequence identity with previously identified papaya meleira virus (PMeV) isolates from Brazil. PMeV, along with its partner virus PMeV2, is known to cause PSD[2][3]. PMeV is a dsRNA virus, while PMeV2 has a single-stranded RNA (ssRNA) genome. Both viruses are encapsidated in particles formed by the PMeV capsid protein and are found in the latex of symptomatic papaya plants[4]. The presence of both PMeV and PMeV2 is necessary for the manifestation of PSD symptoms, which include spontaneous latex exudation and a sticky appearance of the fruit. Phylogenetic analysis, which examines the evolutionary relationships between organisms, placed PSFaV in a clade with Sclerotium rolfsii RNA virus 2 and Phlebiopsis gigantea mycovirus dsRNA 2, both of which are fungus-associated fusagraviruses. This suggests that PSFaV, along with BabMelV, represents a new species within the recently established family Fusagraviridae[5]. The Fusagraviridae family includes viruses that infect fungi, but the identification of PSFaV and BabMelV indicates that this viral family also extends to plant-associated viruses. The discovery of PSFaV is significant because it expands our understanding of the viral agents that can infect papaya. The genetic characterization of PSFaV provides valuable information for the development of diagnostic tools and management strategies to control PSD. Understanding the genetic makeup of PSFaV allows researchers to design specific molecular markers that can detect the virus in infected plants, even before symptoms appear. This early detection is crucial for preventing the spread of the disease and minimizing crop losses. Moreover, the study highlights the importance of phylogenetic analysis in identifying and classifying new viruses. By comparing the genetic sequences of PSFaV with other known viruses, researchers can better understand the evolutionary relationships and potential origins of these pathogens. This information can inform breeding programs aimed at developing papaya cultivars with enhanced resistance to viral infections. In summary, the genetic characterization of PSFaV by researchers at the Escuela Superior Politécnica del Litoral marks a significant advancement in our understanding of papaya-infecting viruses. The study not only identifies a new virus but also provides insights into its evolutionary relationships and potential impact on papaya crops. By building on previous findings related to PMeV and PMeV2[2][3][4], this research paves the way for improved diagnostic and management strategies to combat PSD and ensure the sustainability of papaya production.

GeneticsBiochemPlant Science

References

Main Study

1) Complete genome sequence and phylogenetic analysis of a newly discovered fusagra-like virus infecting Carica papaya in Ecuador.

Published 20th June, 2024

https://doi.org/10.1007/s00705-024-06075-7

Related Studies

2) Battle of Three: The Curious Case of Papaya Sticky Disease.

https://doi.org/10.1094/PDIS-12-19-2622-FE

3) A Capsid Protein Fragment of a Fusagra-like Virus Found in Carica papaya Latex Interacts with the 50S Ribosomal Protein L17.

https://doi.org/10.3390/v15020541

4) The dsRNA Virus Papaya Meleira Virus and an ssRNA Virus Are Associated with Papaya Sticky Disease.

https://doi.org/10.1371/journal.pone.0155240

5) Two Novel Relative Double-Stranded RNA Mycoviruses Infecting Fusarium poae Strain SX63.

https://doi.org/10.3390/ijms17050641


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