Transmission of tobacco rattle virus isolate PpK20 by its nematode vector requires one of the two non-structural genes in the viral RNA 2

This study identifies which viral genes are required for nematode transmission of tobacco rattle virus (TRV) isolate PpK20 by its vector Paratrichodorus pachydermus. The researchers created mutations in the two non-structural genes encoded by viral RNA 2—the 29±4 kDa and 32±8 kDa genes—and tested whether the mutant viruses could be transmitted by nematodes. All mutants replicated and were encapsidated normally after mechanical inoculation into plants. However, mutations affecting the 29±4K gene prevented nematode transmission, while a large deletion in the 32±8K gene had no effect on transmission. The researchers conclude that the 29±4K gene is essential for nematode transmission of TRV-PpK20, whereas the 32±8K gene is dispensable. The findings suggest the 29±4K protein may function similarly to helper components in aphid-transmitted viruses, potentially binding viral particles to receptor sites within the nematode vector.

Key findings

• The 29±4 kDa non-structural protein encoded by TRV RNA 2 is essential for transmission by Paratrichodorus pachydermus nematodes
• The 32±8 kDa non-structural protein is not required for nematode transmission of TRV-PpK20
• Viral mutants with deletions or frameshifts in the 29±4K gene were unable to be transmitted by nematodes despite replicating normally in plants
• The 29±4K protein likely functions in binding viral particles to receptor sites within the nematode vector