The incidence and molecular characteristics of Apple stem grooving virus from pear in China.

Apple stem grooving virus (ASGV) occurs worldwide on apple (Malus pumila), pear (Pyrus pyrifolia), citrus (Citrus reticulata) and lily (Lilium brownii). Its incidence in pears trees from twelve provinces in China was determined using reverse transcription polymerase chain reaction. Overall, 84% of trees were infected with ASGV. Partial sequences of coat protein gene in isolates from pear had 85–100% nucleotide (nt) identities and 91–100% amino acid (aa) identities. The aa identity in the variable region of the movement protein ranged from 49 to 100%. The complete genome of one ASGV isolate (HH) was determined. The isolate showed an overall nt identity of 80–91% to fourteen previously reported isolates from a range of hosts; the highest identity to isolate ASGV-CHN infecting apple in China and the lowest identity to an isolate ASGV-P infecting pear in South Korea. This is the first comprehensive study on the incidence and molecular divergence of ASGV in pear.