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

C Hernandez, PB Visser, DJ Brown and JF Bol Institute of Molecular Plant Sciences, Gorlaeus Laboratories, Leiden, The Netherlands. Tobacco rattle virus isolate PpK20 is transmitted by the nematode Paratrichodorus pachydermus. RNA 2 of the virus determines vector transmissibility and encodes the viral coat protein and two non- structural proteins with molecular masses of 29.4 kDa and 32.8 kDa. Deletions and a frameshift in the two non-structural genes did not interfere with encapsidation or co-replication of RNA 2 with RNA 1 after mechanical inoculation of plants. Mutations that affected the 29.4K gene or both non-structural genes abolished nematode transmission, whereas a large deletion in the 32.8K gene had no effect on transmission by P. pachydermus. It is concluded that the 29.4K gene but not the 32.8K gene is involved in transmission of isolate PpK20 by this vector.