The objectives of this study are 1) isolate and identify PSTVd based on biological, chemical and molecular properties and nucleotide sequence, 2) genetic variability of some potato genotypes to PSTVd by biochemical and molecular markers, 3) elimination of PSTVd through Meristem-tip culture, thermotherapy, chemotherapy, electrotherapy treatments. As well as, production of PSTVd- free microtubers and conservation of PSTVd in vitro by calli cultures.