Identification and characterization of potato spindle tuber viroid in Iran.
2009
Pur Rahim, Reza | Farzad Far, Shirin | Izad Panah, Keramat Ol-Lah | Shahr Aein, Nuh
Potato spindle tuber viroid (PSTVd), the type species of Pospiviroid genous, Pospiviridae family, causes spindle tuber disease on potato. Crop reductions of 17 to 65 % in non-susceptible cultivars and up to 100% in susceptible cultivars have been reported. There is little data on the distribution and molecular properties of Iranian isolates of PSTVd, so in this work we studied the distribution of PSTVd in the main potato cultivation areas in Ardabil, Esfahan, Hamadan, Khorasan and Tehran provinces. Detection was carried out by polymerase chain reaction method using specific primers. Totally 974 potato samples were tested and the results showed that Khorasan province had the highest infection (3.4%), and Tehran, Ardabil, Hamadan and Esfahan with 2.5, 2.1, 1.7 and 0.8 % infections, were recorded, respectively. Tomato fields, as the other important reservoir host for PSTVd, were sampled in the mentioned provinces and totally 777 samples were collected. According to these results, PSTVd infection of tomato samples were recorded as 6.2, 2.6, 2.4, 2.1 and 1.8 % for Khorasan, Esfahan, Tehran, Ardabil and Hamadan provinces, respectively. Our study showed that Physalis floridana, Datura sp., Solanum nigrum serve as reservoir hosts for PSTVd in the surveyed fields. Seven Iranian isolates of PSTVd were selected and their complete genomes were sequenced and aligned with each other and with 12 non-Iranian isolates. Iranian isolates showed up to 6.8 % difference with each other and 0 to 10.9 % difference with non-Iranian isolates. It seems that PSTVd has been introduced into Iran by imported potato tubers and tomato seeds during last decades.
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