Biological and molecular characterization of two Potato virus X- isolates from Hamedan province

The main potato growing areas in Hamadan province including Bahar, Razan and Kabodar-Ahang were surveyed during 2010 and 2011 to find distribution of  Potato virus X. A total of 426 leaf samples (132 and 324 symptomatic and random, respectively) were collected from 9 potato fields. Totally 42 random samples were showed positive reaction with PVX specific antibodies in ELISA assay. The highest virus incidence was recorded in Bahar (18.3 %), followed by Razan (12.5 %) and Kabodar Ahang (9.2 %). Coat protein gene (CP) of two Iran-HB1 and Iran-HK2 PVX isolates from Bahar and Kabodar-Ahang districts, respectively, were amplified (size about 750 bp) by reverse transcriptase polymerase chain reaction (RT-PCR) using specific primers. Evolutionary relationship demonstrated that Iranian isolates fell into Eurasia group. These two isolates with other Iranian PVX isolate from Pisum sativum are closely related together with high bootstrap support. The complete CP nucleotide sequences of Iranian potato isolates were 714 nucleotides long, encoding an ORF with 237 amino acids as previously reported for isolates belong to Eurasia group. The lowest (% 78.7) and highest (% 99.2) identities were found with Netherland (group II) and Iranian (group I) isolates with accession numbers X88785 and FJ461343, respectively, whereas for two Iranian isolates the identities were 100%. Although Iranian isolates were found in the Eurasia population we do not know yet whether these are dominant isolates in this region or not. However, evolutionary comparisons of a large number of isolates from Asia Minor and mid-Eurasia with representative worldwide isolates are necessary to determine this. The present study to our knowledge shows for the first time, the evolutionary relationships of PVX from potato collected in the mid-Eurasian region of Iran.