Abstract:

To investigate the occurrence and genetic diversity of apple viral diseases in the main apple-producing areas along the coastal region of Shandong Province，a total of 57‘Fuji’apple samples were randomly collected in Weihai and Yantai. High-throughput sequencing combined with RT-PCR was employed to identify the virus species present in the samples. Subsequently，coat protein（CP）or movement protein（MP）genes of the detected viruses from Shandong apple isolates were cloned，and sequence similarity and phylogenetic analyses were performed. The results indicated that four plant viruses were detected in the 57 apple samples：apple stem pitting virus（ASPV），apple stem grooving virus（ASGV），apple chlorotic leaf spot virus（ACLSV），and citrus leaf blotch virus（CLBV），with detection rates of 63.16%，87.72%，78.95%，and 1.75%，respectively. Notably，81.48% of the samples exhibited mixed infections，with co-infections of ASPV，ASGV，and ACLSV accounting for 61.11%. Nine CP gene sequences of ASGV，two CP gene sequences of ASPV，nine CP gene sequences of ACLSV，and one MP gene sequence of CLBV were cloned from the positive samples. The Shandong isolates of ASGV and ACLSV had a close relationship with previously reported domestic isolates. The nine ACLSV isolates clustered into groups P205，SHZ，and B6；the nine ASGV isolates formed four distinct branches；while the two ASPV isolates clustered together within the same group. One CLBV isolate grouped with other species isolates.

Key words: apple, viral diseases, genetic diversity