Archivio Journal of Plant Pathology

Abstract:

A survey for apple viruses was conducted in October of 2014 in Shanxi, Gansu, Sichuan, Liaoning and Hebei provinces of China. A total of 189 leaf samples with mosaic symptoms and five symptomless samples were collected and tested for viruses. Apple mosaic virus (ApMV) (Lakshmi et al., 2011; Robertson, 2012) was not detected by RT-PCR with total RNA and primers ApMV-F (5’-CGTGAGGAAGTTTAGGTTG-3’)/ApMV-R (5’-GCCTCCTAATCGGGGCATCAA-3’). Neither were Tobacco mosaic virus (TMV), Turnip mosaic virus (TuMV), Potato virus Y (PVY) and Potato virus X (PVX) by a multiplex RT-PCR assay previously developed in our laboratory, with the exception of Cucumber mosaic virus (CMV), for which a partial fragment (322 bp) of the coat protein (CP) gene was amplified from 153 symptomatic samples using specific primers CMV-F (5’-GATAAGAAGCTTGTTTCGCG-3’)/CMV-R (5’-GCTCGATGTCGACATGAAGT-3’). To confirm these preliminary results, primer pair CMV-CP-F (5’-A TGGACAAA TCTGAA TCAACC-3’)/ CMV-CP-R (5’-TCAGACTGGGAGCACCCC-3’) were designed to amplify a 657 bp CMV CP amplicon by simplex RT-PCR. The expected product was obtained from each sample identified as positive by multiplex RT-PCR. Five amplicons were randomly selected for cloning and sequencing (GenBank accession Nos. KP307919-KP307922 and KP641344). Sequence alignments showed the highest CMV sequence identity at the nucleotide level (97.3% to 99.2%) of the five isolates with that of a CMV isolate from tobacco in Sichuan province (KJ746016). Phylogenetic analysis indicated the five isolates cluster into CMV subgroup I. Using the CMV-specific monoclonal antibody 3C12 (Yu et al., 2005), the 153 symptomatic samples were positive for CMV in ELISA. No virus was detected in the five symptomless samples. To our knowledge, this is the first report of CMV infecting apple in China.