First Report of Prune Dwarf Virus in Stone Fruit Trees in Azerbaijan

Stone fruits (family Rosaceae) are extensively produced throughout Azerbaijan. Prunus dwarf virus (PDV, Ilarvirus PDV, genus Ilarvirus, family Bromoviridae) has a wide host range, including stone fruit trees, but information on its occurrence in Azerbaijan is lacking. The aim of this research was to survey Azerbaijani stone fruit orchards for PDV. A total of 134 leaf samples were collected from 49 plum (Prunus domestica), 8 apricot (P. armeniaca), 13 almond (P. amygdalus), 22 peach (P. persica), 25 sweet cherry (P. avium), and 17 cherry plum (P. cerasifera) trees in 2018-2019. Sweet cherry, plum, and cherry plum trees displayed typical chlorotic leaf spot symptoms. Leaf samples were analyzed by DAS-ELISA using PDV-specific serological reagents (Neogen - Scotland, UK). PDV was detected in five plum, five sweet cherry, and two cherry plum samples, but not in apricot, almond, and peach samples. To confirm the presence of PDV in the three former Prunus hosts, total RNA was isolated from symptomatic leaves (0.5 g) derived from the trees that tested positive in DAS-ELISA, as previously described (Foissac et al. 2005), and analyzed by RT-PCR using the OneStep RT-PCR kit (Qiagen) and primers designed in the coat protein gene of PDV (F: 5′-GAAAGCCTACTACCCGATCACAAAG-3′ and R: 5’-CAATTCCGTACACCTTGGTATCAGC-3′). Primers were also included for the NADH dehydrogenase subunit 5 that was used as an internal control (Menzel et al. 2002). RT-PCR included an initial denaturation for 5 min at 95 °C and 34 cycles of 10 s at 95 °C, 20 s at 50 °C, 20 s at 72 °C, followed by a final extension of 2 min at 72 °C. DNA amplicons were resolved by electrophoresis on 2% agarose gels and visualized under UV illumination after staining with GelRed (Biotium, Fremont, CA). Amplicons of the expected size (282 bp) were obtained from the three infected Prunus hosts, confirming the DAS-ELISA results. Next, PCR products from each host [plum (Sheki 3; Ganca 60; Aghdam 83), sweet cherry (Guba 98), and cherry plum (Guba 192)] were purified with ExoSAP-IT (Thermo Fischer Scientific, Waltham, MA) and Sanger sequenced at the Cornell Biotechnology Resource Center (Ithaca, NY). Sequences of Azerbaijani PDV isolates were deposited in GenBank as accession numbers PX864247-PX864251. Sequence analyses with the DNASTAR Lasergene software package (v17.3.0.57) showed high sequence identity among Azerbaijani PDV isolates at both the nucleotide (89.7-93.9%) and amino acid (89.2%-94.6%) levels. A high nucleotide identity ranging from 93.8% to 94.8% was also recorded between PDV Azerbaijani isolates and isolates from other geographic origins, including isolates 235C from Slovakia (KU949346), K1 from Czechia (AF208738), PE15-28 from Germany (GU066798), PD2 from Turkiye (EF524265), and HSY4-1 from China (KC965106). To the best of our knowledge, this is the first report of PDV in plum, sweet cherry, and cherry plum trees in Azerbaijan. This result expands our knowledge on the distribution of PDV. The occurrence of PDV alongside prunus necrotic ringspot virus (Mustafayev et al. 2026), apple chlorotic leaf spot virus (Mustafayev et al. 2025a), and apple stem grooving virus (Mustafayev et al. 2025b) underscores the need for the implementation of a stone fruit certification program in Azerbaijan.