Occurrence and molecular variability of apple-associated Luteovirus isolates from apple in China based on coat protein genes

Apple-associated Luteovirus (AaLV) was recently found in apple trees in China. How commonly AaLV occurs in apple and how much genetic diversity is present among samples from various locations and apple cultivars are not reported but are investigated here. In this study, 162 samples from 13 locations, covering 13 apple cultivars of Malus pumila and one wild apple of Malus sieversii in China were collected, their coat protein (CP) genes were amplified by reverse transcription-polymerase chain reaction and the variability of the CP genes was analysed. The occurrence ratio of AaLV was 37.04% in apple trees in China, the AaLV isolates showed little variation on their CP genes, the geographic location or host cultivars had no consistent effect on the occurrence, variation and phylogenetic characters of AaLV. The results of this study will provide information on further study of the molecular characteristics and epidemiology of AaLV.