S-67. Occurrence and detection of some stone fruit viruses in Poland

Stone fruit trees grown in Polish climate conditions are attacked by many viruses. The most common and the best characterized are Prune dwarf virus (PDV), Prunus necrotic ring spot virus (PNRSV) and Plum pox virus (PPV) but heavy losses of crop yielded in some commercial cultivation can be caused by other viruses. Economically important are Little cherry virus-1 (LChV-1), Little cherry virus -2 (LChV-2), Cherry mottle leaf virus (CMLV), Cherry necrotic rusty mottle virus (CNRMV) and Cherry green ring mottle virus (CGRMV). In case of CGRMV, CNRMV and LChV-1 natural vectors have not been identified so far. That is why it is possible to eliminate these viruses from the nursery and commercial cultivation by using healthy plant material. In case of LChV-2, and CMLV, for which the natural vectors exist, plant material must be under systematic control. Considering that stone trees are important in fruit production in Poland, studies on occurrence and detection of LChV-1, LChV-2, CMLV, CNRMV and CGRMV were conducted. Totally 298 plant materials of sour cherry, sweet cherry, peach, apricot and plum trees originating from different growing regions of Poland were tested for the presence of these pathogens. RNA was isolated from leaves using an RNeasy kit (Qiagen) and than evaluated by reverse transcription polymerase chain reaction (RT-PCR) amplification. Several primers sets were used for amplification of the viruses genome fragments. The amplified cDNA fragments of viruses were cloned into bacterial vector pCR 2.1 – TOPO, sequenced and analyzed using Lasergene (DNASTAR) software. The expected viral specific fragment was amplified from 42 tested trees infected with CGRMV. Amplification of a 419 bp coat protein gene product confirmed infection of 38 trees with LChV-1. A 438 bp fragment corresponding to the methyltransferase gene of the LChV-2 was amplified from one source. The sampled trees were tested negative for CMLV and CNRMV using RT-PCR.