Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2004
Publication Date: 6/30/2004
Citation: Kaplan, I., Lee, L., Ripoll, D.E., Liang, D., Palukaitis, P., Gray, S.M. 2004. A surface loop of the potato leafroll virus coat protein is involved in virion stability and aphid transmission. Phytopathology. 94:S58.
Technical Abstract: Two acidic domains of the potato leafroll virus (PLRV) coat protein separated by 55 amino acids that are predicted to be adjacent surface features on the virion, were the focus of a mutational analysis. A total of eleven, site-directed mutants were generated from a cloned infectious cDNA of PLRV. The cloned PLRV was delivered to plants using Agrobacterium-mediated mechanical inoculation. Alanine substitutions of any of the three amino acids of the sequence EWH (amino acids 171-173) affected the ability of the coat protein to assemble stable particles and the viral RNA to move systemically in four plant hosts. A similar phenotype was observed when alanine was substituted for D177. Alanine substitution of E109, D173 or E176 reduced the accumulation of virus in agroinfiltrated tissues and reduced the efficiency of systemic infection, but did not affect virion assembly. The efficiency of aphid transmission of these three mutants was also reduced relative to wild-type virus. A replacement of V169 with lysine did not affect virion assembly or plant infection, but did reduce the efficiency of aphid transmission. A structural model of the PLRV capsid predicts that the four amino acids critical for virion assembly are located in a depression located at the three-fold axis of symmetry, and the other amino acids affecting plant infection and/or aphid transmission are located around the perimeter of the depression.