Occurrence of two little cherry viruses in stone fruits in Serbia

Abstract

Little cherry virus 1 (LChV-1, genus Velarivirus) and little cherry virus 2 (LChV-2, genus Ampelovirus), members of the family Closteroviridae, are considered important cherry pathogens worldwide. In susceptible sweet and sour cherry cultivars, LChV-1 and LChV-2 can cause severe yield losses and reduce fruit quality. Beside cherries, both viruses were found in other stone fruit species: plums, apricots, peaches, and almonds. The aim of our study was to access the presence of LChV-1 and LChV-2 in major Prunus species cultivated in Serbia. During 2017−2020 202 stone fruit samples (67 sweet cherries, 17 sour cherries, 53 apricots, 38 plums, and 27 peaches) were collected from several regions of Serbia. All samples were analyzed with reverse transcription polymerase chain reaction (RT-PCR). TNA was extracted from fresh leaves with a 2% CTAB buffer. Reverse transcription was performed using random hexamer primers. PCR reactions were performed using the LCV1U/LCV1L primer pair that amplify a 419 bp fragment of the LChV-1 3' non-translated region and LCV2UP2/LCV2LO2 for the amplification of the 438-bp fragment of the LChV-2 methyltransferase gene, respectively. PCR products were analyzed by agarose gel electrophoresis. Selected isolates of both viruses (10 LChV-1, and one LChV-2) were sequenced and phylogenetically analyzed. The presence of LChV-1 was confirmed in 18 analyzed samples (8.9%), and LChV-2 in only one sweet cherry sample (0.5%). LChV-1 was detected in 10 sweet cherries, five apricots, and three plums. Analyzed viruses were not detected in any of the tested sour cherry and peach samples. Serbian LChV-1 isolates showed 76.10–100% nucleotide (nt) identity. A phylogenetic analysis identified Serbian LChV-1 isolates from plums and sweet cherries as members of the G5 phylogenetic group. Two apricot isolates belong to the G3 phylogenetic group and one isolate to the G5 group. This report describes the first report of little cherry virus 1 infecting plums in Serbia and confirms the presence of isolates from G3 and G5 phylogroups in Serbian stone fruit orchards. Out of all tested isolates, little cherry virus 2 was confirmed in only one sweet cherry tree.