Abstract:

In order to clarify the incidence and genetic variation of apple necrotic mosaic virus （ApNMV）in Gansu Province，a total of 93 apple leaf samples with mosaic or without obvious symptoms were tested by reverse transcription-polymerase chain reaction（RT-PCR）. The results showed that the average incidence of ApNMV among the collected samples was 66.67%，which indicated that this virus spread widely around the surveyed regions of Gansu Province. The full-length coat protein（CP）genes generated from mine samples were cloned and sequenced. The similarity of nucleotide and amino acid sequence identities of ApNMV CP genes of the nine isolates ranged from 92.3%-99.7%，and 93.6%-99.1%，respectively，while they shared that of the available 18 ApNMV isolates from NCBI database of China，India and Japan，which ranged from 86.7%-99.7%，and 87.1%-99.7%，respectively. The phylogenetic tree were constructed based on the complete CP gene，and the ApNMV isolates clustered into five groups，among which，nine ApNMV isolates from Gansu and other ApNMV isolates to form GroupⅠ，GroupⅡand GroupⅤ，respectively. Finally，a potential recombination event was tested among the nine complete nucleotide sequences of ApNMV CP genes.

Key words: apple, ApNMV, CP, RT-PCR genetic diversity, recombination