| Potato virus Y (PVY) is one of the most widespread viruses and causes huge losses to solanaceous crops including potato, tobacco, eggplant and tomato.Two PVY isolates, AQ4 and FZ10, were isolated from tobacco plants in Aiqiu and Tai'an of Shandong Province. Both isolates could induce mosaic and mottle in 12 tobacco cultivars including Zhongyan 100.The complete genomic sequences of AQ4 and FZ10 were determined from seven or eight overlapping cDNA clones obtained from RT-PCR and 5′-RACE. Excluding the poly(A) tail, the genome of AQ4 and FZ10 were 9700 and 9699 nucleotides in length, respectively. Both of them encoded a polyproetin of 3061 amino acids, which was then cleaved into ten products by three virus-encoded proteases. AQ4 shared highest identity of 97.3% with isolate 261-4 at nucleotide level, while FZ10 shared highest identity of 95.2% with PVY-12. Both AQ4 and FZ10 were recombinants of N and O parents. The nucleotides (nt) 1-496 and 2497-9700 of AQ4 genome were from isolate Oz (PVYO),while nt 497-2496 from isolate CH-605 (PVYN). The nt 1-496 and 2497-6533 of FZ10 genome were from isolate SASA-110 (PVYO),while nt497-2496 and 6534-9699 were from isolate CH-605 (PVYN).The phylogenetic analysis results showed that AQ4 was clustered to strain PVYN:O while FZ10 PVYNTN. Both of them had N-type HC-Pro. However, neither of them induced necrosis on tobacco. These reulsts implied that there existed other motif besides HC-Pro regulating the veinal necrosis symptom in PVY genome.
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