Development of a multiplex RT-PCR and the occurrence characteristics of viral diseases in sweet cherry trees in the Shandong Province, China

Viral diseases have become a major threat to sweet cherry production worldwide. In this study, a broad survey on 17 target species of viruses was performed by RT-PCR detection of leaf samples with suspected symptoms of viral infection collected from 110 orchards in 13 cities of the Shandong Province, the largest sweet cherry production area in China. Eight viruses were identified, including little cherry virus 1, cherry green ring mottle virus, prunus necrotic ring spot virus, cherry virus A, cucumber mosaic virus, plum bark necrosis stem pitting-associated virus, prune dwarf virus and little cherry virus 2. To simultaneously detect different viruses infecting sweet cherry trees, a multiplex RT-PCR method for these 8 viruses was developed and performed. Based on the multiplex RTPCR data, sweet cherry trees in most orchards were co-infected with multiple viruses, even some trees were coinfected with eight species of viruses. All of these viruses predominantly infected sweet cherry trees cultivars Hongdeng and Tieton. These viruses appear to be not evenly distributed among different regions in the Shandong Province, which Yantai and Tai'an cities represented two centers of sweet cherry virus diseases in the Shandong Province. These data will provide the basis for the detection and management of viral diseases in sweet cherry production.