Preliminary characterization of potato virus Y (PVY) populations in Algerian potato fields

To date, only limited data are available concerning the viral pressure present in potato crops in Algeria. For three consecutive years, surveys were conducted in potato fields in the main Algerian potato-growing regions during the mid-season crop cycle (January to March). A total of 285 potato samples were characterized to define the prevalence of the five most common virus species: Potato virus Y (PVY), Potato leaf roll virus (PLRV), Potato virus X (PVX), Potato virus A (PVA) and Potato virus S (PVS). The results showed a higher incidence of PVY compared to the other four viruses. Because of this predominance of PVY and its distribution in all of the scouted regions, an analysis was carried out on the diversity of PVY populations. From a panel of 185 samples, serologically confirmed as being solely infected by PVY, 96.7% were found to be of serotype-N, and only 3.2% of serotype-O. A set of 31 PVY isolates was further analyzed by biotyping on tobacco and by molecular typing (RT-PCR, sequencing), targeting the nucleotide sequence polymorphism in the 5'NTR/P1 region and the three recombination junctions within the HC-Pro/P3 (RJ2), VPg/NIa (RJ3) and CP (RJ4) regions. All 28 PVY isolates from serotype-N inducing vein necrosis on tobacco were recombinant PVYNTN isolates. Among the three PVY isolates of serotype-O, two were typed as PVYN-Wi and induced vein necrosis on tobacco. This is the first report of the identification of NTN and Wilga type isolates in Algeria.