Cloning of the potato virus Y genes encoding the capsid protein CP and the nuclear inclusion protein NIb

Abstract

DNA was synthesized complementary to the RNA genome of potato virus Y (PVY; strain GO 16) and cloned into λ vectors. The size of PVY-specificEco RI-restricted cDNA ranged from 0.3 to approximately 22kb. Two of the cDNA clones each of which contained some 4kb of cDNA sequence starting from the 3′-polyadenylated terminus were characterized by sequence analysis. Presence of a single open reading frame suggests that PVY-specific proteins are synthesized as a polyprotein precursor. As with other sequenced potyvirus RNAs the gene for the PVY capsid protein CP is located next to the 3′-untranslated region followed by the genes for the putative RNA polymerase (nuclear inclusion protein NIb) and the virus-specific protease (nuclear inclusion protein NIa). The 3′-trailing sequence of the PVY strains cloned is highly homologous to the corresponding region of pepper mottle virus (PeMV) and suggests that PeMV is not a distinct member of the potyvirus group, but another strain of PVY.