Elimination of Plum Pox Virus (PPV) in plum (Prunus domestica L.) cvs Kyustendilska sinya and Veljevka through in vitro techniques

The aim of the present research was to obtain PPV-free plants of Prunus domestica cv. 'Kyustendilska Sinya' (KS) and cv. 'Valjevka' (Val) via in vitro techniques. Mother trees of Kyustendilska Sinya' and 'Valjevkal were tested through DAS ELISA for PPV as well as other important viruses: Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV), Prune dwarf virus (PDV) and Prunus necrotic ringspot virus (PNRSV). The test results showed that plants have high concentration only of PPV and free of another tested viruses. Young shoots were collected in May 2000 and surface-sterilized. Explants were cultured on Murashige and Skoog medium, supplemented with 0.56 mg/l BAP, 0.001 mg/l IBA, 30 g/w saccharose and 5.8 g/l agar, pH 5.6. After initiation, small apex buds with 2-3 unfolded leaves were subcultured at 3-weeks intervals on the same medium. DAS ELISA was used to determine the virus content in the plants at each 3(th) subculture. To the fourth subculturing 35.3 % of obtained subclones of KS and 33.3 % of Val were free of PPV. After 8 passages 88 % of established subclones of KS and 100 % of Val were PPV-free. After acclimatization the virus-free plants will be retested.