PLUM POX VIRUS STRAINS IN BULGARIA
Sharka or plum pox has a long presence in Bulgaria. In this study, 790 plum, peach and apricot samples were analyzed by TAS-ELISA. 465 samples (58.9%) reacted positive for PPV. The highest level of PPV infection was detected in the plum orchards (86.06%), followed by the peach (46.5%) orchards/single grown trees and in the apricot (32.05%) orchards/single grown trees. Molecular typing performed by strain-specific IC-RT-PCR analyses showed that the most prevalent strain was PPV-M (46.7%), followed by PPV-Rec (43.9%) and PPV-D (7.9%). The rate of mixed infection was 1.5%. Distinct epidemiological situations depending on the stone-fruit species were evidenced. On plum, PPV-Rec was the most prevalent strain (69.1%), followed by PPV-M (20.1%) and PPV-D (8.3%). The rate of mixed infections was 2.5%. On the contrary to the plums, peaches and apricots were essentially infected by PPV-M (89.2 and 80.6 %, respectively). On apricot, PPV-Rec was detected more frequently than PPV-D (11.9 and 7.5% respectively), whereas on peach the opposite pattern was found (7.5 and 3.3% for PPV-D and PPV-Rec, respectively). To assess the genetic diversity, 27 isolates were partially characterised by direct sequencing of the PCR products spanning the (Cter)NIb-(Nter)CP and the (Cter)P3-6K1-(Nter)CI coding regions. Phylogenetic analysis of these isolates confirmed their RT-PCR-based strain typing. Bulgarian PPV-Rec isolates clustered with PPV-Rec isolates retrieved from the NCBI database in both analysed regions. Phylogenetic analyses of PPV-M isolates based on the NIb-CP genomic region showed that they fell into the Ma and Mb clusters, while on the base of the P3-6K1-CI genomic region, part of the isolates formed a third sub-cluster more related to Mb, than to Ma isolates. Regardless of the analysed region, the analyzed PPV-D isolates grouped together with D strain isolates from Europe, Canada and USA.
Kamenova, I., Borissova, A., Dragoyski , K., Milusheva, S., Stefanova, B., Dallot, S. and Glasa, M. (2015). PLUM POX VIRUS STRAINS IN BULGARIA. Acta Hortic. 1063, 47-54
sharka, survey, PPV strains, ELISA, IC-RT-PCR