Helper component mutations in nonconserved residues associated with aphid transmission efficiency of a pepper isolate of potato virus Y
1999
Llave, C. | Martinez, B. | Diaz-Ruiz, J.R. | Lopez-Abella, D.
The aphid transmission properties of a pepper isolate of potato virus Y belonging to the pathotype 1-2 (PVY 1-2) have been characterized. PVY 1-2 was not transmitted in plant-to-plant experiments, although purified virus particles were efficiently transmitted when supplemented with heterologous helper component (HC) of the transmissible isolate PVY 0 AT through membrane acquisition assays, indicating that its coat protein was functional in transmission. Additionally, virions of PVY 1-2 were able to bind to different HCs in in vitro binding assays. Analysis of the sequence of the PVY 1-2 HC gene and comparison with that of PVY 0 AT revealed 19 nucleotide differences, but only 2 resulted in amino acid changes, one of which induced a change of charge. Neither of these two amino acid changes occurred within the cysteine-rich domain, nor did they coincide with conserved motifs of the HC protein known to be involved in aphid transmission and which are present in all known potyviruses. However, both changes are located in positions highly conserved among PVY strains. The possible role of both mutations on the activity of the PVY 1-2 HC in aphid transmission is discussed.
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